Characteristics of grey wastewater

Characteristics of grey wastewaterEva Eriksson *, Karina Auﬀarth, Mogens Henze, Anna Ledin Environment & Resources DTU, Technical University of Denmar...

77 downloads 41 Views 159KB Size

Download PDF

Urban Water 4 (2002) 85–104 www.elsevier.com/locate/urbwat

Characteristics of grey wastewater Eva Eriksson *, Karina Auﬀarth, Mogens Henze, Anna Ledin Environment & Resources DTU, Technical University of Denmark, Bygningstorvet, Building 115, DK-2800 Kgs. Lyngby, Denmark Received 1 February 2001; received in revised form 7 September 2001; accepted 25 October 2001

Abstract The composition of grey wastewater depends on sources and installations from where the water is drawn, e.g. kitchen, bathroom or laundry. The chemical compounds present originate from household chemicals, cooking, washing and the piping. In general grey wastewater contains lower levels of organic matter and nutrients compared to ordinary wastewater, since urine, faeces and toilet paper are not included. The levels of heavy metals are however in the same concentration range. The information regarding the content of xenobiotic organic compounds (XOCs) is limited. From this study, 900 diﬀerent XOCs were identiﬁed as potentially present in grey wastewater by the use of tables of contents of household chemical products. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Characteristics; Grey wastewater; Greywater; Literature review; Reuse; Water quality; Xenobiotic organic compounds

1. Introduction There is an increasing interest in the reuse of wastewater in many parts of the world, including both industrial and developing countries. One reason is water shortage, caused by too low amounts of rainfall in combination with high evaporation (e.g., Australia) or too large demands of freshwater from the population (e.g., Japan). On the other side in some countries, the driving force for reuse of wastewater is environmental and economical considerations. The reuse will lower the total costs for wastewater handling, since there will be a reduced load of water to the treatment plants. Grey wastewater is deﬁned as wastewater without any input from toilets, which means that it corresponds to wastewater produced in bathtubs, showers, hand basins, laundry machines and kitchen sinks, in households, ofﬁce buildings, schools, etc. The total grey wastewater fraction has been estimated to account for about 75 vol% of the combined residential sewage (Hansen & Kjellerup, 1994 and references therein). Possibilities of reuse for grey wastewater have come into special focus. The explanation is that this fraction of wastewater is less polluted than municipal wastewater in the absence of faeces, urine and toilet paper. The

*

Corresponding author. Tel.: +45-4525-1600; fax: +45-4592-2850. E-mail address: [email protected] (E. Eriksson).

characteristics will be of importance when evaluating the possibilities for reuse, including the need for pre-treatment. Health aspects, mainly micro-organisms, and environmental perspectives like accumulation of xenobiotic organic compounds (XOCs) and metals in soil and groundwater, have to be taken into account. Use of grey wastewater for urinal and toilet ﬂushing is one of the possibilities since the water that is used for toilet ﬂushing in many countries today is of drinking water quality. It has been estimated that 30% of the total household water consumption could be saved by reusing grey wastewater for ﬂushing toilets (Karpiscak, Foster, & Schmidt, 1990). Reuse of grey wastewater from bathrooms has been successfully used in Germany where it has been shown that it is technically feasible and health requirements can be met. Substantial volumes of water ð15–55 l pd1 Þ can be reused and a dual system is possible (Nolde, 1999). A review of the current water demands in large buildings revealed that not only grey wastewater from bathrooms but also washing machine wastewater or stormwater is needed to provide suﬃcient recycled water for non-potable uses (Surendran & Wheatley, 1998). Outdoor applications for grey wastewater could be irrigation of lawns on college campuses, athletic ﬁelds, cemeteries, parks and golf courses as well as in the domestic garden (Okun, 1997). Washing of vehicles and windows, ﬁre protection, boiler feedwater and concrete production are examples of other suggested usages (Okun, 1997; Santala et al., 1998). In

1462-0758/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 1 4 6 2 - 0 7 5 8 ( 0 1 ) 0 0 0 6 4 - 4

86

E. Eriksson et al. / Urban Water 4 (2002) 85–104

addition, grey wastewater could be used to develop and preserve wetlands (Otterpohl, Albold, & Olgenburg, 1999). An alternative way of handling grey wastewater is to inﬁltrate it into the ground and thereby make a shortcut in the urban hydrological cycle. There are a number of problems related to the reuse of untreated grey wastewater. The risk of spreading of diseases, due to exposure to micro-organisms in the water, will be a crucial point if the water is to be reused for e.g. toilet ﬂushing or irrigation. There is a risk that micro-organisms in the water will be spread in the form of aerosols that are generated as the toilets are ﬂushed (Albrechtsen, 1998; Christova-Boal, Eden, & McFarlane, 1996; Feachem, Bradley, Garelick, & Mara, 1983). Both inhaling and hand to mouth contact can be dangerous. Growth within the system is another source for micro-organisms and some chemicals. Dixon, Butler, and Fewkes (1999a) have outlined the health risks associated with the microbial contamination of grey wastewater by making a hazard identiﬁcation and a risk characterisation of the organisms potentially present and the exposure routes and proposed a framework for new health guidelines for reuse. Several countries and states have/or are working on the guidelines for reuse of treated wastewater for nonpotable reuse. In the USA, California has limited the levels of total coliforms to max 2.2 per 100 ml in reclaimed water for use in toilet and urinal ﬂushing, commercial laundries and in decorative fountains. In Florida, reclaimed water for toilet ﬂushing and for the irrigation of recreation areas must contain no detected faecal coliforms per 100 ml (Crook & Surampalli, 1996). WHO guidelines for treated wastewater used for irrigation of agricultural crops and public sports ﬁelds limit faecal coliforms to <1000 per 100 ml and nematodes to <1 per litre (World Health Organization, 1989). In Australia, guideline values of thermotolerant coliforms are set on four levels, for recreational applications these are <150 per 100 ml and for higher contacts e.g., irrigation of salad vegetables are lighter at <10 per 100 ml (Gregory, Lugg, & Sanders, 1996). In Germany, the corresponding limits are total coliforms < 100 ml1 and faecal coliforms < 10 ml1 as well as Pseudomonas aeruginosa < 1 ml1 (Nolde, 1999 and references therein). The risk for pollution of soil and receiving waters due to the content of diﬀerent pollutants is another question that has been raised concerning inﬁltration and irrigation with grey wastewater. For instance, Christova-Boal et al. (1996) stated that inﬁltration and irrigation may lead to elevated concentrations of detergents (for example) in the soil and some plants may suﬀer due the alkaline water. These pollutants, XOCs, originate from the chemical products (soaps, detergents, etc.) used in the households’ for personal care products and cleaning detergents (for example). Many are synthetic and their

eﬀect and spreading is only partially known. The soaps are alkali salts of long-chained fatty acids, while the detergents consist of surfactants as well as a number of other chemicals to improve the function e.g. builders, bleaches, enzymes, etc. The grey wastewater that is going to be reused must also be of satisfactory technical quality. Suspended solids may cause clogging of the distribution system. Another related problem is the risk of sulphide, which will give oﬀensive odours and thereby cause public nuisance (Jeppesen, 1996). It can thereby be concluded that it is necessary, when planning reuse of grey wastewater, to properly characterise the water with respect to physical parameters, as well as the content of both chemical compounds and micro-organisms.

2. Objectives The main objective of this study is to review the present knowledge with respect to the characteristics of grey wastewater. As the information is limited, the methodology includes estimates. The information that is needed for estimation of the characteristics will be obtained from combining the data available from measurement in grey wastewater, with a survey of which chemical compounds and micro-organisms that theoretically could be expected to be present. The potential content of chemical compounds will be based on the declaration of contents on the packages for the chemical household products as well as on industrial production statistics. The priority of the parameters with respect to risk will be based on a method for environmental hazard identiﬁcation usually applied to new compounds that are going to be introduced into the market.

3. Characteristics of grey wastewater The characteristics of grey wastewater depend ﬁrstly on the quality of the water supply, secondly on the type of distribution net for both drinking water and the grey wastewater (leaching from piping, chemical and biological processes in the bioﬁlm on the piping walls) and thirdly from the activities in the household. The compounds present in the water vary from source to source, where the lifestyles, customs, installations and use of chemical household products will be of importance. The composition will vary signiﬁcantly in terms of both place and time due to the variations in water consumption in relation to the discharged amounts of substances. Furthermore, there could be chemical and biological degradation of the chemical compounds, within the transportation network and during storage.

E. Eriksson et al. / Urban Water 4 (2002) 85–104

87

3.1. Physical and chemical parameters

3.2. Xenobiotic organic compounds

Physical parameters of relevance are temperature, colour, turbidity and content of suspended solids. High temperatures may be unfavourable since they favour microbial growth and could in supersaturated waters, induce precipitation (e.g. calcite). Food particles and raw animal ﬂuids from kitchen sinks and soil particles, hair and ﬁbres from laundry wastewater are examples of sources of solid material in the grey wastewater. Measurements of turbidity and suspended solids give some information about the content of particles and colloids that could induce clogging of installations such as the piping used for transportation or sandﬁlters used for treatment. Although the amount of solids is expected to be lower than in combined wastewater, the risk for practical problems related to clogging should not be neglected. The reason is that the combination of colloids and surfactants (from detergents) could cause stabilisation of the solid phase, due to sorption of the surfactants on the colloid surfaces. This prevention of agglomeration of the colloidal matter will reduce the eﬃciency of a pre-treatment step including settling of solid matter. The eﬀects from inﬁltrating grey wastewater on soil pH and buﬀering capacity will be determined by the alkalinity, hardness and pH of the inﬁltrating water. However, the eﬀect observed will also be inﬂuenced by the natural buﬀering capacity of the soil. The properties of the soil, regarding the sorption capacity of pollutants, will change as a result of the inﬁltration. In addition, measurements of alkalinity and hardness will, in a way similar to turbidity and content of suspended solids, give some information concerning the risk of clogging. These parameters are largely determined by the quality of the drinking water, while the inﬂuence of chemicals added during the use of the water is generally limited in relation to these parameters. Measurements of the traditional wastewater parameters like BOD, COD and the concentration of nutrients (N and P) will also give valuable information. The content of BOD and COD will indicate the risk of oxygen depletion due to degradation of organic matter during transport and storing and thereby the risk for sulphide production. Among the other pollutants, the content of heavy metals (e.g. Al, Fe, Mn, Cd, Cu, Pb, Hg, Zn, Ni, Cr) and XOCs will be of importance. One other important factor to take into consideration is what happens during storage of grey wastewater; the characteristics of the fresh grey wastewater and that stored can diﬀer substantially. Dixon, Butler, Fewkes, and Robinson (1999b) have looked at the impact storage has on grey wastewater. They found that storage for 24 h improved the quality of the water but storage for more than 48 h could be a serious problem as the dissolved oxygen was depleted.

The XOCs that could be expected to be present in grey wastewater constitute a heterogeneous group of compounds and that is why they are given special attention in this paper. They originate from the chemical products used in households such as detergents, soaps, shampoos, perfumes, preservatives, dyes and cleaners. Kitchen wastewater contains lipids (fats and oils); tea, coﬀee, soluble starch, diary products and glucose, while the wastewater produced from laundry will contain diﬀerent types of detergents, bleaches and perfumes. 3.2.1. Large volume (bulk) XOCs One way to select the compounds that should be included in a monitoring program could be based on production data. Those compounds that are produced and consumed in the largest quantities, the so-called bulk compounds, could be expected to cause the largest problems, when introduced into the environment. According to the data presented in Table 1, covering the consumption statistics for some household products, it can be expected to ﬁnd large quantities of soaps and detergents in the grey wastewater. Use diﬀers slightly between countries, but they are within the same order of magnitude; a Danish consumer uses 2.3 kg per year of shampoo and conditioner, while the Swedish consumer uses 0.9–1.1 kg of shampoo per year. The amount of softeners used in Europe in 1991 ranged from 2.5 kg per person and year for the Italians up to 9.2 kg per each Belgian (Puchta et al., 1993). However, it should be noted that these data just illustrate the consumption of household products, and not the consumption of individual compounds. Such information is extremely diﬃcult to obtain. 3.2.2. XOCs present in household chemicals according to the table of contents An alternative way to select the relevant compounds for characterisation of grey wastewater could be based on what compounds are potentially found in the household’s chemicals in combination with an environmental hazard identiﬁcation. Based on the information available in the declaration-of-contents on the diﬀerent types of common Danish household products, covering products from shower creams to powder laundry detergents, at least 900 diﬀerent organic chemical substances and compound groups can be listed. These are most likely to be present in household wastewater. The XOCs listed were divided into 14 diﬀerent groups depending on their functions in the chemical products (Table 2). All chemical products used in households usually contain several compounds from the diﬀerent groups. The ﬁndings above indicate that the number of

88

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Table 1 Calculation of the yearly consumption of household products per person Chemical product

Country

Yearly consumption (106 kg)

Yearly consumption per person ðkg person1 year1 Þ

Household and industrial detergents Household detergents Laundry detergents Laundry detergents Laundry detergents Laundry detergents Laundry detergents Shampoo and conditioners Shampoo Soap Softeners

Denmark Sweden Denmark Finland Norway Sweden USA Denmark Sweden Sweden Europe

105a 4.4b 40c 27c 23c 49c 1000d 12e 8–10b 8b –

19.8 0.5 7.5 5.2 5.2 5.5 3.7 2.3 0.9–1.1 0.9 6.0f

Population size: Denmark – 5.3 million in 1998 (Statistics Denmark, 1999), Finland – 5.2 million in 1999 (Statistics Finland, 2000), Norway – 4.4 million in 1998 (Statistics Norway, 2000), Sweden – 8.9 million in 1998 (Statistics Sweden, 1999), USA – 272.9 million in 1999 (National Center of Health Statistics, 2000). a The National Consumer Agency in Denmark (1999). b Karlstr€ om and Svensson (1995). c Swedish Society for Nature Conservation (2000). d Jenkins (1998). e Pedersen and Madsen (1998). f Puchta, Krings, and Sandk€ uhler (1993).

Table 2 Groups of compounds found in common household chemicals in Denmark Compound group

Number of substances in the group

Amphoteric detergents Anionic detergents Cationic detergents Non-ionic detergents Bleaches Dyes Emulsiﬁers Enzymes Fragrances and ﬂavours Preservatives Softeners Solvents UV ﬁlters Miscellaneous

20 73 34 65 16 26 28 4 197 79 29 67 23 238

diﬀerent chemical constituents that could be identiﬁed and quantiﬁed in grey wastewater in the future will be numerous. Some of the compounds in Table 2 could be placed in more than one group, but it was decided to place them in the group that describes the dominant function of the compound. The major compounds in the list are the surfactants used in detergents, dishwashing liquids and hygiene products i.e. non-ionic, anionic and amphoteric surfactants. Other large groups are the fragrances and ﬂavours, the solvents and the preservatives. The solvents are used to dissolve organic compounds like fragrances in otherwise water-based chemicals. Preservatives are added to the vast majority of the household chemicals to

prevent microbiological growth in the product. As they are biocides and fungicides, they are toxic in some concentration. Some compounds do not ﬁt into any of the groups, and have been placed in the group: miscellaneous. 3.2.3. Environmental hazard identiﬁcation The risk assessment was based on the classiﬁcation of the XOCs with respect to toxicity, bioaccumulation and biodegradation according to a method commonly used for the evaluation of new chemicals that are going to be introduced into the market (see e.g. Van Leeuwen & Hermens, 1995). The compounds were divided into eight diﬀerent groups depending on how environmentally hazardous the compounds are (see Table 3). Out of the approximately 900 substances identiﬁed as present in household chemicals, a total of 66 compounds were categorised as priority pollutants i.e. were placed in the ﬁrst three groups with the highest environmental impact (Table 3). Of these, 34 are diﬀerent types of surfactants (an-, non-, cationic and amphoteric). For instance, compounds or groups of compounds like LAS, nonylphenol- and other alkylphenol-ethoxylates are included. Six diﬀerent preservatives and seven softeners are also among the prioritised 66 compounds. Four of the softeners are esters of phthalic acid e.g. DEHP. Only 211 of the compounds could be evaluated based on the available information about toxicity, bioaccumulation and degradation. It can, therefore, not be excluded that the number of priority pollutants will increase dramatically if more information becomes available for the remaining 700 compounds.

E. Eriksson et al. / Urban Water 4 (2002) 85–104 Table 3 Prioritised chemical compounds and the priority criteria

Table 3 (Continued)

Compound group

Compound

Priority

Amphoteric detergents

Cocamidopropyl betaine Alkylamide betaines Alkylamidopropyl betaines Alkyl betaines Amidopropyl betaines Amphoglycinates Lauriminodipropionates Lauroamphodiacetates

2 3 3 3 3 3 3 3

a-Methylestersulphonate a-Oleﬁnsulphonate Alkyl benzene sulphonates Sulphonates Alkane sulphonates Alkyl ether sulphates Alkyl sulphates Alkyl sulphosuccinates Isotridecanol ethoxylates Panthenol

2 2 2 2 3 3 3 3 3 3

Benzalkonium chloride N-Hexadecyltrimethyl ammonium chloride DHTDMAC DSDMAC DTDMAC Alkyltrimethylammonium chloride DADMAC

1 1

Alkylphenol ethoxylates (APEO) Nonyl phenol (NPE) Alcohol ethoxylates (AEO) Alkyl amide ethoxylates Alkyl amine ethoxylates Fatty alcohols (EO/PO) polymers Fatty alcohol ethoxylates (AEO) Coconut diethanolamide Ethylene glycol

1

Anionic detergents

Cationic detergents

Non-ionic detergents

1 1 2 3

Compound group

Compound

Priority

Softeners

Bis-(2-ethylhexyl)phthalate (DEPH) Diisononylphthalate (DNP) Ethylenediaminetetramethylene phosphonate (EDTMP) Phosphonates Dibutylphthalate (DBP) Diethylphthalate (DEP) Nitrilotriacetic acid (NTA)

1

1 2 3 3

Solvents

Heptane 1,2,4-Trichlorobenzene Diethanolamine Ethanolamine Isopropanol Phenol Xylene

1 2 3 3 3 3 3

Misc.

2-Propene nitrile

3

1 1

Priority 1: Not biodegradable, potentially bioaccumulative; BCF > 100, log Kow > 3, EC=LC50 < 1 mg l1 and N; R50/53. Priority 2: Biodegradable, potentially bioaccumulative; BCF > 100, log Kow > 3, EC=LC50 < 1 mg l1 and N; R50/53. Priority 3: Biodegradable, not potentially bioaccumulative; BCF < 100, log Kow < 3, EC=LC50 < 1 mg l1 and N; R50.

2

3.2.4. By-products and degradation products By-products can be formed when diﬀerent chemicals in the grey wastewater react with each other. Oxidation and microbiological activity may also lead to production of degradation products that have other properties than the parent compounds. For instance, the presence of chloro-containing powder detergents in machine dishwashers has been found to increase the content of adsorbable organic halogens (AOX) (Naturv ardsverket, 1992).

2 3

3.3. Micro-organisms

3

1 2 2 2 2

3,30 -Dichlorobenzidine 4,40 -Methylenebis(2-chlorobenzenamine) o-Aminoazotoluene Benzidine o-Anisidine

1 2

Fragrances and ﬂavours

Hexyl cinnamic aldehyde AHTN HHCB Styrene Benzene-1,3-diol p-Cresol

1 2 2 2 3 3

Preservatives

Bronopol Bronidox 5-Chloro-2-methyl-4isothiazolin-3-one Imidazolidinyl urea Triclosan Quaternium-15

1 1 1

Dyes

89

2 3 3

1 1 3

Pathogenic viruses, bacteria, protozoa and helminths escape from the bodies of infected persons in their excreta and may be passed onto others via exposure of wastewater (see Table 4). These micro-organisms can be introduced into grey wastewater by hand washing after toilet use, washing of babies and small children connected with diaper changes and diaper washing, as well as from uncooked vegetables and raw meat. Knowledge about the introduction, survival and transformation of micro-organisms in a grey wastewater system is a highly relevant issue to evaluate. Eschericia coli is commonly used as an indicator of faecal contamination and by investigating its content in grey wastewater valuable information on health hazards can be retrieved. Additionally, some viruses, e.g. enteroviruses, can be spread in faecally contaminated waters.

90

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Table 4 Water and excreta-related pathogens Bacteria Bacteroides fragilis Biﬁdobacterium adolescentis Biﬁdobacterium longum Campylobacter jejuni Clostridium perfringens E. coli Eubacterium spp. Faecal coliforms Helicobacter pylori Lactobacilli Legionella pneumophilia Leptospira Peptococcus spp. Peptostreptococcus spp. Pseudomonas aeruginosa Salmonella typhi S. paratyphi Other salmonellae Shigella sonnei Other shigella Streptococcus bovis S. durans S. equines S. faecalis S. faecium Vibrio cholerae Other vibrios Yersinia enterocolitica Protozoa Balantidium coli Cryptosporidium parvum Cyclospora cayetanenis Encephalitozoon hellem Entamoeba histolytica Enterocytozoon bienusi Giardia lamblia Neagleria

Helminths Ancylostoma duodenale; Necator americanius Ascaris lumbricoides Clonorchis sinensis Diphyllobothrium latum Enterobius vermicularis Fasciola hepatica Fasciolopsis buski Gastrodiscoides hominis Heterophyes heterophyes Hymenolepsis spp. Metagonimus yokogawai Optisthorchis felineus O. viverrini Paragonimus westermani Schistosoma haematobium S. japonicum S. mansoni Strongyloides stercoralis Taenia saginata T. solium Trichuris trichiura Viruses Adenoviruses Coxsackieviruses Echoviruses Hepatitis A virus H. E virus H. F virus Polioviruses Reoviruses Rotaviruses

From Feachem, Bradley, Garelick, and Mara (1980), World Health Organization (1989), Mara and Feachem (1999), Stenstr€ om, Hoﬀner, and Br€ omssen (1980), Stenstr€ om (1996).

Other parameters can be of interest in places where persons extremely susceptible to infections (e.g. elderly, HIV-positive and people with heart transplants) can be exposed to the reused grey wastewater (e.g. toilet ﬂushing). Additionally persons who may have had contact with special infectious sources, i.e. refugees, immigrants who have visited their native countries and people who travel to places with special health problems, can carry other pathogens when returning from these countries. Among the relevant organisms are bacteria like Salmonella typhi Salmonella paratyphi, parasites like roundworms and some special viruses like Hepatitis and enteroviruses (Albrechtsen, 1998; World Health Organization, 1989). If the grey wastewater is reused for irrigation or inﬁltration, parasitic protozoa and helminths will not be a

problem in relation to groundwater contamination due to their large size, which results in their removal by ﬁltration as the water percolates under gravity. Bacteria and virus contamination of groundwater may, on the other hand, be a serious problem. Organisms that are relatively resistant to disinfection will prevail longer within the system i.e. Cryptosporidium and Giardia (protozoa). Clostridium perfringens (protozoa) spreads by spores and can survive longer than most other microorganisms. The spores can be used as indicators of cumulative faecal contamination. Many species of helminths can infect humans but they cannot multiply within the host, with the exception of Strongyloides (Feachem et al., 1980). Legionella poses a speciﬁc threat since it can be spread by aerosols and can be inhaled during surface irrigation or toilet ﬂushing. Due to the fact that it is resistant to water treatment processes, it can become a serious problem (Dixon et al., 1999a). In Table 4, there is a list of pathogenic water and excreta related microorganisms found to be present in diﬀerent types of waters including wastewaters. Although urine should not be present, it has been noticed that, from time to time, traces of urine are present in grey wastewater from bathrooms. Urine is generally sterile and harmless but some infections may cause pathogens to be passed into the urine. The three principal infections are urinary schistosomiasis (Schistosoma haematobium), typhoid (Salmonella typhi) and leptospirosis (Leptospira) (Feachem et al., 1980).

4. Reported characteristics of grey wastewater A summary of the data available in the literature focusing on the characterisation of diﬀerent types of grey wastewater is given in Tables 5–8. It should be noted that the diﬀerent types of grey wastewater have diﬀerent characteristics and that is why the data have been divided into four diﬀerent categories; bathroom, laundry, kitchen and grey wastewater of mixed origin. This kind of information will be of high importance when evaluating the potential for reuse or other alternative handling (inﬁltration) of grey wastewater, in the future. It should also be noted that there are diﬀerences in the quality of the data presented in the tables. Some references only report average or single values, while others have taken many samples over a long time period and furthermore report ranges and number of samples. It is well known that a grab sample might be very misleading since the concentration varies over the day and is diﬀerent on diﬀerent days of the week. It would be highly important to evaluate the data in the literature in order to get some ‘‘typical’’ values or ranges for each parameter in the diﬀerent types of grey wastewater. That kind of information would be appreciated and useful in

E. Eriksson et al. / Urban Water 4 (2002) 85–104

evaluation of the best method for treatment or in a risk assessment of reuse of grey wastewater, for example. Unfortunately the information available is still too limited for most of the parameters (see below), and therefore has not been included in the present study. 4.1. Physical parameters The temperature of grey wastewater was found to vary within the range 18–38 °C (Tables 5–8). The rather high temperature is due to the use of warm water for personal hygiene. This relatively high temperature may cause problems since it favours microbiological growth. The elevated temperatures may also result in CaCO3 precipitation since the solubility of CaCO3 and some other inorganic salts decrease at elevated temperatures. The values obtained for turbidity measurements in laundry water vary a lot during the laundry cycle. The wash cycle has signiﬁcantly higher turbidity values compared to the rinse cycle, 39–296 and 14–29 NTU, respectively. Christova-Boal et al. (1996) noted that the highest wash cycle turbidity value originated from a family with extensive outdoor activities. For the other grey wastewaters, the turbidity was found to be in the range 15.3–240 NTU. It should be noted that no values for turbidity in grey wastewater from kitchen sinks were found in the literature. The publications including measurements of suspended solids showed that the numbers obtained varied in the range 17–330 mg l1 , where the highest values originated from laundry and kitchen. The laundry wastewater may contain sand and clay from clothes and zeolites from detergents. The grey wastewater from kitchen sinks may contain sand and clay from the rinsing of vegetables, shoes, etc. The numbers can be compared to traditional household wastewaters, which have been found to have suspended solids in the concentration range from 120 to 450 mg l1 (Henze, Harremo€es, la Cour Jansen, & Arvin, 2001). The values obtained for total solids varied a lot and ranged between 113 and 2410 mg l1 where the highest values originated from the kitchen, from both the sink and an automatic dishwasher machine. 4.2. Chemical parameters Grey wastewater that originates from the laundry is alkaline and has generally pH-values in the range 8–10, while the other types of grey wastewater generally had somewhat lower pH-values (range 5–8.7; Tables 5–8). The pH in the grey wastewater depends largely on pH and alkalinity in the water supply. However, the higher pH-value observed in grey wastewater from laundry shows that the uses of chemical products are of importance as well.

91

The measurements of chemical oxygen demand (COD) gave concentrations of 13-ca. 8000 mg l1 , while measurements of biological oxygen demand (BOD) were somewhat lower (range 5–1460 mg l1 ). There are differences between the various grey wastewater fractions; the bathroom fraction contains 184–633 mg l1 COD and 76–300 mg l1 BOD; the laundry fraction contains 725–1815, respectively 48–472 mg l1 ; the kitchen fraction 26–1380, respectively 5–1460 mg l1 whereas the mixed grey wastewater range was between 13-ca. 8000 and 90–360 mg l1 . The corresponding levels in household wastewater are COD 210–740 and BOD 150–530 mg l1 (Henze et al., 2001). Most of the COD derives from household chemicals like dishwashing and laundry detergent, so COD is expected to be at the same levels as the COD in household wastewater. These ﬁndings illustrate that the diﬀerent types of grey wastewater could be suitable for diﬀerent types of reuse, and there will be diﬀerent needs for pre-treatment depending on both the types of grey wastewater and the intended use of the water. The quantities of oxygen in grey wastewater have been measured by Shin et al. (1998) and Santala et al. (1998) who found concentrations in the ranges 2.2–5.8 (dissolved oxygen) and 0:4–4:6 mg l1 , respectively. The total nitrogen concentration of the grey wastewater is lower than in domestic wastewater, 0.6–74 and 20–80 mg l1 , respectively (Tables 5–8 and Henze et al., 2001). The main source for nitrogen in domestic wastewater, urine, should not be present in grey wastewater. The kitchen wastewater contributes the highest levels of nitrogen to the grey wastewater (concentration range 40–74 mg l1 ). The corresponding values for ammonium are <0.05–25 compared to 12–50 mg l1 (Tables 5–8 and Henze et al., 2001). The lowest levels are found in the bathroom and laundry wastewater. Washing detergents are the primary source of phosphates found in grey wastewater in countries that have not yet banned phosphorus-containing detergents (Jeppesen, 1996). Concentrations between 6 and 23 mg Tot-P l1 can be found in traditional wastewaters in areas where phosphorus detergents are used. However, in regions were non-phosphorus detergents are used the concentrations range between 4 and 14 mg l1 (Henze et al., 2001). This can explain why the total phosphorus and phosphate concentrations are generally higher in laundry grey wastewater compared to bathroom grey wastewater, 0.1–57 and 0:1–2 mg l1 , respectively (Tables 5–8). 4.2.1. Metals and other ground elements The concentration of metals and other elements will largely be dependent on the concentrations and quality of the water from the water works. Laundry wastewater was found to contain elevated sodium levels compared to other types of grey wastewater. The sodium in the

92

Table 5 Characteristics of grey wastewater originating from bathrooms Type of grey wastewater (in mg l1 unless otherwise stated)

Volume ðl ðpdÞ1 Þ

Chemical properties pH Electrical cond. (lS cm1 ) Alkalinity (as CaCO3 Þ Hardness (as CaCO3 ) BOD BOD5 BOD5F BOD7 COD CODt CODd CODMn CODCr SCOD Dissolved oxygen Oxygen TOC TOCF Inorganic carbon Oil and grease Chloride Fluoride Cyanide Sulphate Nutrients Tot-N Total KJN NH4-N NH3 & NO2 NO3 –N NO3 & NO2 NO2

Bathroom

Shower/bath

Wash basin

Bath

Wash basin

Shower

Bath and shower

Shower

Bathtub

Bathroom sink

Shower/bath

Shower water

Siegrist, Witt, and Boyle (1976)

Christova-Boal et al. (1996)

Surendran and Wheatley (1998)

Surendran and Wheatley (1998)

Almeida, Butler, and Friedler (1999)

Almeida et al. (1999)

Almeida et al. (1999)

Nolde (1999)

Nolde (1999)

Laak (1974)

Laak (1974)

Rose, Sun, Gerba, and Sinclair (1991)

Burrows, Schmidt, Carnevale, and Schaub (1991)

38

–

–

–

16

13

12

30–35

15–20

32

8

–

–

92 631

102 558

28–96

49–69

29 60–100 60–240 250 120 190 85 48–120

76 318

54

181

200

9

72

153

40 240 1260–137

6.4–8.1 82–250 24–43

170 100

559

520

7.6

8,1

6.7–7.4 48–67 43–52

216

252

424

433

192

236

282

383

76–200 50–100 100–200 210 184

100 61

104

40

26

20

298 221

70–300 113–633

501 221

30–38

37–78 9.0–18

17 2

5–10 4.6–20 <0.1–15

0.4 <0:05–0:20

1.56

0.53

1.1

0.3

1.2

1.34

1.15

0.9

0.34

4.2

6

6.3

0.36

0.28

0.11–0.37

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Physical properties Temperature (°C) Colour (Pt/Co) Odour (Threshold no.) Turbidity (NTU) TS TSS TVS TVSS SS VS VSS TDS DS

Shower/bath

Tot-P PO4 –P P Ground elements Al B Ba Ca K Mg Na S Se Si Tot-S

2 1

0.11–1.8

0.2–0.6 1.63

45.5

5.3

13.3

19.2

0.94

48.8

<1:0 <0:1 3.5–7.9 1.5–5.2 1.4–2.3 7.4–18 1.2–3.3 <0:001 3.2–4.1

0.001 <0:01

0.06–0.12 0.34–1.1

0.2–6.3

0.00054a

0.111a

0.003a 0.059a

XOCs Detergents Fatty acids ðn-C10 –n-C18 Þ

Detected

Type of grey wasewater (per 100 ml unless otherwise stated) Microbiological properties Total bacterial pop. (SPC) Total coliforms 70–8200 500–2:4 107 Faecal coliforms 1–2500 170–3:3 103 Faecal Streptococci 1–70000 79–2:4 103 E. coli Thermostable coliforms Colifager PFU ml1 Enterococcus Heterotrophic bacteria ml1 CFU ml1 Campylobacter spp Nd Candida albicans Cryptosporidia Nd Entamoeba histolytica Giardia Nd Pseudomonas aeruginosa Salmonella Nd Shigella 1 Staphylococcus aureus ml a

Reported as mg l

1

6 106 600

5 104 32

104 –105 101 –103

103 –105 101 –103

105 –106

105 –106

107 –3 108 105 6 103

>100

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Heavy metals Heavy metals (R-value) Ag As Cd Co Cr Cu Fe Hg Mn Ni Pb Zn

Nd

Nd

1–5 105

1

in the reference but are in lg l .

93

94

Table 6 Characteristics of grey wastewater originating from laundries Type of grey wastewater Clothes wash

Clothes rinse

Laundry

Washing

Washing

Laundry

Laundry wash

Laundry rinse

Laundry

Siegrist et al. (1976)

Siegrist et al. (1976)

Christova-Boal et al. (1996)

Surendran & Wheatley (1998)

Almeida et al. (1999)

Laak (1974)

Rose et al. (1991)

Rose et al. (1991)

Hargelius, Holmstrand, & Karlsson (1995)

Volume ðl ðpdÞ1 Þ

40 For both steps

–

–

17

28

–

–

34

Physical properties Temperature (°C) Colour (Pt/Co) Odour (Threshold no.) Turbidity (NTU) TS TSS TVS TVSS SS VS VSS TDS DS

in mg l1 unless otherwise stated 32 28

Chemical properties pH Electrical cond. (lS cm1 ) Alkalinity (as CaCO3 ) Hardness (as CaCO3 ) BOD BOD5 BOD5F BOD7 COD CODt CODd CODMn CODCr SCOD Dissolved oxygen Oxygen TOC TOCF Inorganic carbon Oil and grease Chloride Fluoride Cyanide Sulphate

in mg l1 unless otherwise stated

50–70 50–210 1340 280 520 170

410 120 180 69

108 658

39–296

14–29

165

88–250

68 330

2.7 97

590 g ðpdÞ1 9.3–10 190–1400 83–200

380 250

150 110

8.1

472

282

725

725

48–290 5.1 12.8

1815 1164

280 190

100 72

110 25 8.0–35 9.0–88

g ðpdÞ1 0.28

in mg l1 unless otherwise stated 21 6 0.7

0.4

0.6

0.4

1.0–40 <0:1–1:9

0.10–0.31

10.7

2.0

11.3

1.6

2.0

1.26

0.1–3.47

0.06–0.33

0.04

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Nutrients Tot-N Total KJN NH4 –N NH3 & NO2 NO3 –N NO3 & NO2

g ðpdÞ1

NO2 Tot-P PO4 –P P

57 15

21 4

in mg l1 unless otherwise stated

Heavy metals Heavy metals (R-value) Ag As Cd Co Cr Cu Fe Hg Mn Ni Pb Zn

in mg l1 unless otherwise stated

0.2 101

21.0

171.0a

1.5

<1:0–21 <0:1–0:5

0.019 14 5 3.1 44

3.9–12 1.1–17 1.1–2.9 49–480 9.5–40 <0:001 3.8–49

<0:01

<0:002 <0:038

0.001–0.007 0.00063b

<0:05–0:27 0.29–1.0

0.09–0.32

<0:038 <0:012 <0:025 0.058 0.46 0.00029 0.029 <0:028 <0:063 0.44

0.322b

0.033b 0.308b

XOCs Detergents Fatty acids ðn-C 10 –n-C18 Þ Microbiological properties Total bacterial pop. (SPC) Total coliforms Feacal coliforms Feacal Streptococci E. coli Thermostable coliforms Colifager PFU ml1 Enterococcus Heterotrophic bacteria ml1 CFU ml1 Campylobacter spp Candida albicans Cryptosporidia Entamoeba histolytica Giardia Pseudomonas aeruginosa Salmonella Shigella Staphylococcus aureus ml1 a b

No. ðpdÞ1

per 100 ml unless otherwise states 85–890000 9–16000 1–1300000

190–150000 35–7100 1–230000

2:3 103 –3:3 105 110–1:09 103 23–<2:4 103

7 105 728

107 –3 108 199 126

107 –3 108 56 25 2; 5 106 28; 2 106 28; 8 106 102 103

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Ground elements Al B Ba Ca K Mg Na S Se Si Tot-S

0.062–42

Nd Nd nd Nd

Phosphorus containing detergents. Reported as mg l1 in the reference but are in lg l1 .

95

96

Table 7 Characteristics of grey wastewater originating from kitchen sinks Type of grey wastewater Kitchen sink

Dishwasher

Hand- & dishwash

Kitchen 64% laundry & washbasin

Kitchen sink

Kitchen sink

Kitchen sink

Kitchen

Kitchen

Kitchen

Siegrist et al. (1976)

Siegrist et al. (1976)

G€ unther (2000)

Shin et al. (1998)

Surendran & Wheatley (1998)

Almeida et al. (1999)

Laak (1974)

Hargelius et al. (1995)

Hargelius et al. (1995)

Hargelius et al. (1995)

Volume ðl ðpdÞ1 Þ

19 For both

–

–

–

13

14

16

6

Physical properties Temperature (°C) Colour (Pt/Co) Odour (Threshold no.) Turbidity (NTU) TS TSS TVS TVSS SS VS VSS TDS DS

in mg l1 unless otherwise stated 27 38

Chemical properties pH Electrical cond. (lS cm1 ) Alkalinity (as CaCO3 ) Hardness (as CaCO3 ) BOD BOD5 BOD5F BOD7 COD CODt CODd CODMn CODCr SCOD Dissolved oxygen Oxygen TOC TOCF Inorganic carbon Oil and grease Chloride Fluoride Cyanide Sulphate

in mg l1 unless otherwise stated

1500 440 870 370

235

185.0

4

7.8

3.1

196

g ðpdÞ1 6.3–7.4 20.0–340.0 5.0

1460 800

536

676

936

1380

1040 650 47

16 25.6

4.9 3.8

8.9 15.3

0.37

g ðpdÞ1 0.36

0.31

0.005

0.002

0.004

0.09

0.06

0.073

1079 644

26–194.0 2.2–5.8 880 720

600 390

in mg l1 unless otherwise stated 74 40 6

15.4–42.8 0.2–23.0

4.5

4.6

0.3

5.44

3.72 0.3

0.3

0.45

5.8

0.56

74 31

68 32

15.6

26.0

12.7

3.73

0.4–4.7

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Nutrients Tot-N Total KJN NH4 –N NH3 & NO2 NO3 –N NO3 & NO2 NO2 Tot-P PO4 –P P

2410 720 1710 670

23 g ðpdÞ1

in mg l1 unless otherwise stated

Ground elements Al B Ba Ca K Mg Na S Se Si Tot-S

in mg l

1.8

1.1

0.025 30 19 3.3 180

0.018 13 59 7.3 92

0.028 23 40 4.3 29

14

13

<0:002 <0:038 <0:007 <0:013 0.13 0.26 1 <0:0003 0.038 <0:025 <0:062 0.21

0.013 <0:038 <0:007 <0:013 0.072 0.14 0.6 <0:0003 0.031 <0:025 0.14 0.12

unless otherwise stated

a

0.00052

0.050a

0.005a 0.096a

<0:002 <0:038 <0:006 <0:012 <0:025 0.068 1.2 0.00047 0.075 <0:025 <0:063 1.8

XOCs Detergents Fatty acids ðn-C10 –n-C18 Þ Microbiological properties Total bacterial pop. (SPC) Total coliforms Feacal coliforms Feacal Streptococci

No. ðpdÞ1

per 100 ml unless otherwise stated

35848

E. coli Thermostable coliforms Colifager PFU ml

1

94427

550 106 898 106 250 106 40 800 106 375 106 61300 106 <3 <48000

6

0:16 10 9:6 106 0:16 106 96:6 106 <3 <18000

5150 1:2 106 0:13 106 30 106 0:2 106 47 106 <3 <69000

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Heavy metals Heavy metals (R-value) Ag As Cd Co Cr Cu Fe Hg Mn Ni Pb Zn

1

0.67

Enterococcus Heterotrophic bacteria ml1 CFU ml1 Campylobacter spp Candida albicans Cryptosporidia Entamoeba histolytica Giardia Pseudomonas aeruginosa Salmonella Shigella Staphylococcus aureus ml1 a

Reported as mg l1 in the reference but are in lg l1 .

97

98

Table 8 Characteristics of grey wastewater originating from mixed sources Type of grey wastewater Bath and dish water

Laundry, kitchen and bathroom

Greywater no grabage disposal

Greywater

Shower, washbasin and laundry

Greywater storage tank

Greywater

Septic sullage

Greywater and urine

Hargelius et al. (1995)

Gerba et al. (1995)

Hypes (1974)

Albrechtsen (1998)

Santala et al. (1998)

Rose et al. (1991)

Sheikh (1993)

Jeppesen (1993)

Fittschen & Niemczynowicz (1997)

–

–

–

–

–

–

110

Volume ðl ðpdÞ1 Þ

74

–

Physical properties Temperature (°C) Colour (Pt/Co) Odour (Threshold no.) Turbidity (NTU) TS TSS TVS TVSS SS VS VSS TDS DS

g ðpdÞ1

in mg l1 unless otherwise stated

15.3–78.6

6.4

19.1–48.0

g ðpdÞ1

in mg l1 unless otherwise stated 6.7–7.6 6.9–7.5 320–390

20–140

17–68

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Chemical properties PH Electrical cond. ðlS cm1 Þ Alkalinity (as CaCO3 ) Hardness (as CaCO3 ) BOD BOD5 BOD5F BOD7 COD CODt CODd CODMn CODCr SCOD Dissolved oxygen Oxygen TOC TOCF Inorganic carbon Oil and grease Chloride

18–38 30–>100ðPtCl6 Þ 2–4 30–68 mg l1 SiO2 113–451

22– >200

45–330

6.5–7.2 Up to 20 000

5–7

6.6–8.7 325–1140

149–198 112–152 119.8

12.6 20.7

270–360

283–549

90–290

164.6 361

13–240

Up to 4000 Up to 8000

0.4–4.6 60–92

20–30

3.1–12

Fluoride Cyanide Sulphate Nutrients Tot-N Total KJN NH4-N NH3 & NO2 NO3 –N NO3 & NO2 NO2 Tot-P PO4 –P P

Heavy metals

1

g ðpdÞ 0.54

12–40

7.9–110

unless otherwise stated 0.6–5.2

0.03

<0:05–0:80

Up to 25

1.8–3.0

18.1

0.15–3.2

2.1–31.5 <1:0–25:4

0–4.9

<0:1–0:8

<0:1–2:1 all <0:1 0.6–27.3

0.16 50–68

Up to 30

in mg l1 unless otherwise stated 1.7 0.032 21 6.6 6.6 21

3.9

4–35

0.100–3.550 <1 15–17

0.016–0.120 11–35

1.5–2.8 68–93

5–19 29–230

< 0:01

in mg l1 unless otherwise stated

Heavy metals (R-value) Ag <0:002 As <0:038 Cd <0:006 Co <0:012 Cr 0.036 Cu 0.056 Fe 1.4 Hg <0:0003 Mn 0.061 Ni <0:025 Pb <0:063 Zn 0.14 XOCs Detergents Fatty acids (n-C10 –n-C18 )

in mg l

1

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Ground elements Al B Ba Ca K Mg Na S Se Si Tot-S

0.70–0.95 0.02 83–160

0.001–0.3 <0:05 <0:01 <0:01– <0:03

all <0:010

<0:05 0.08–0.16 <0:05–0:20

<0:01026 0.018–0.390 0.094–4.370 all <0:001 0.014–0.075 <0:015–0:027 <0:050–0:150 <0:010–0:440

<0:05 <0:05 <0:01–0:10 0.37–1.60

0.23

<0:05 0.171

Detected

99

100

Table 8 (Continued) Type of grey wastewater

Microbiological properties Total bacterial pop (SPC) Total coliforms Feacal coliforms Feacal Streptococci E. coli Thermostable coliforms Colifager PFU Enterococcus Heterotrophic bacteria ml1 CFU ml1 Campylobacter spp Candida albicans Cryptosporidia Entamoeba histolytica Giardia Pseudomonas aeruginosa Salmonella Shigella Staphylococcus aureus ml1

Laundry, kitchen and bathroom

Greywater no grabage disposal

Greywater

Shower, washbasin and laundry

Greywater storage tank

Greywater

Septic sullage

Greywater and urine

Hargelius et al. (1995)

Gerba et al. (1995)

Hypes (1974)

Albrechtsen (1998)

Santala et al. (1998)

Rose et al. (1991)

Sheikh (1993)

Jeppesen (1993)

Fittschen & Niemczynowicz (1997)

74

–

–

–

–

–

–

–

110

1

No.ðpdÞ

40 106 236 106 655 106 388 103

per 100 ml unless otherwise stated 107:2 –108:8 105:4 –107:2 <1–24 000 <1 400 000 9–270000 <1 800 000 11–>2000

nd

nd nd

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Volume ðl ðpdÞ1 Þ

Bath and dish water

E. Eriksson et al. / Urban Water 4 (2002) 85–104

laundry wastewater may be caused by the use of sodium as counterion to several anionic surfactants used in powder laundry detergent (Jeppesen, 1996) and the use of sodium chloride in ion-exchangers. Only relatively low amounts of heavy metals have been reported in the literature, with one exception for Christova-Boal et al. (1996) who found notably high levels of zinc in the grey wastewater. The laundry wastewaters contained 0:09–0:34 mg l1 while the bathroom wastewater contained 0.2–6.3 mg Zn l1 (Tables 5–8). The other authors found concentrations in the range < 0:01–1:8 mg l1 . One reason for the high values in the bathroom wastewater could be some chlorine tablets that had been used for disinfecting. These tablets are acidic and that may cause leaching of zinc from the plumbing. 4.2.2. Xenobiotic organic compounds The number of publications including XOCs in their investigations of grey wastewater is extremely low. One publication described a screening with GC-MS, which showed that the total amount of organic constituents in grey wastewater consisted of more than 95% of detergents. These detergents were found to contribute with 60% of the measured CODCr (Santala et al., 1998). A second publication, also a GC-MS screening, of shower wastewater revealed that the even-numbered long chain fatty acids of C10 –C18 originating from soap were present (Burrows et al., 1991). 4.3. Chemicals present in household wastewater 4.3.1. Chemicals added to the wastewater during water consumption One way to select relevant compounds with respect to monitoring in grey wastewater is to evaluate data available from characterisation of ordinary household wastewater, since the sources for XOCs will be the same in the two wastewaters. A review covering the published literature showed that approximately 500 diﬀerent organic and inorganic compounds have been analysed in domestic wastewater (Hagebro & Andersen, 1990; Jepsen & Gr€ uttner, 1997; Mattson, Averg ard, & Robinson, 1991; Paxeus, 1996; Paxeus, Robinson, & Balmer, 1992; Paxeus & Schr€ oder, 1996; Wilkie, Hatzimihalis, Koutouﬁdes, & Connor, 1996). Paxeus et al. (1992) found that the major organic components in the inﬂuent to a wastewater treatment plant were long-chain fatty acids and their esters. The main sources of these compounds are soap, edible oils and fat. The second largest group were the washing and cleaning related products consisting of ethers of PEG & PPG, alkylphenols (e.g. nonylphenol) and ethoxylated alkylphenols e.g. octylphenol ethoxylates originating from detergents (Paxeus, 1996). Perfume additives have also been found. These perfumes mainly consist of

101

synthetic musks and terpenes (Paxeus & Schr€ oder, 1996). Households also contribute more than 70% of the total load of the phthalates and adipates (Paxeus et al., 1992). Notable is that both the PAHs and several phenols were detected in domestic wastewater. Domestic sources contribute 20–70% of the naphthalene (Mattson et al., 1991). Forty-six compounds and compound groups overlapped between the list in Table 2 and the 500 compounds identiﬁed in household wastewater. These were mainly the softeners, preservatives and fragrances that have been detected in the domestic wastewater. In these analyses, the detergents (an-, non- and cationic) have been reported as summary parameters and a comparison of the 172 compounds in the corresponding groups in the list of household chemicals in Table 2 cannot be performed. 4.3.2. By-products and degradation products Domestic appliances have been found to contribute 25–45% of the AOX, which originates from the usage of chlorine as bleach and disinfectant (Mattson et al., 1991). Furthermore, the Swedish Environmental Protection Agency showed that washing with powder detergents containing reactive chlorine led to higher concentrations of dioxin in the eﬄuent. They found 14– 28 times higher concentrations of the dioxin TCDD and up to 54 times higher concentration of the dibenzofurane TCDF compared to the water produced by dishwasher machines without any powder detergents used (Naturv ardsverket, 1992). 4.4. Micro-organisms Kitchen wastewater may contain several types of micro-organisms caused by the contamination of uncooked food and raw meat. In this literature review, it was found that the faecal coliforms and total coliforms had not been analysed for in kitchen wastewater. E. coli concentrates were observed in the range 1:3 105 –2:5 108 per 100 ml, while the thermotolerant coli were found in the range 9:4 104 –3:8 108 per 100 ml and the faecal streptococci between 5150 and 5:5 108 per 100 ml. The laundry wastewater was found to contain 9 104 –1:6 104 per100 ml faecal coliforms, 56 105 –8:9 105 per 100 ml of total coliforms and faecal streptococci in the range 1 106 –1:3 106 per 100 ml. The bathroom wastewater contained up to 3 103 per 100 ml faecal coliforms, 70–2:4 107 per 100 ml of total coliforms and 1–7 104 per 100 ml of faecal streptococci. This means that the amounts of microorganisms found were slightly lower than for the kitchen wastewater. Burrows et al. (1991) have analysed shower water from US military facilities. In that study Candida

102

E. Eriksson et al. / Urban Water 4 (2002) 85–104

albicans, Pseudomonas aeruginosa and Staphylococcus aureus were included, because these micro-organisms are commonly found in the mouth, nose and throat of humans. C. albicans and P. aeruginosa were not found. Other micro-organisms examined were Campylobacter spp, Cryptosporidia, Giardia and Salmonella spp (Christova-Boal et al., 1996) as well as Shigella and Entamoeba histolytica (Sheikh, 1993). However, none of them were detected either. Micro-organisms may enter the grey wastewater system during usage but there is also a risk of re-growth. Rose et al. (1991) examined the survival of Salmonella typhimurium, Shigella dysenteriae and poliovirus in grey wastewater. No re-growth was detected, but the numbers of Salmonella remained stable for two days and subsequently decreased. The numbers of Shigella decreased more rapidly, while the poliovirus was found to have a similar survival rate as Salmonella in grey wastewater during the ﬁrst 3–4 days. The content of micro-organisms in grey wastewater reused for toilet ﬂushing in Denmark has been analysed by Albrechtsen (1998). Two micro-organisms were included in the study; Enterococcus and E. coli. The survey showed that grey wastewater-ﬂushed toilets contained higher levels of micro-organisms, compared to toilets ﬂushed with water from the water works. It was also found that E. coli did not grow in the grey wastewater system, but can survive and be detected after 14 days (Albrechtsen, 1998).

5. Conclusions From this literature survey, it can be concluded that there is an urgent need for more information about the characteristics of diﬀerent types of grey wastewater in order to be able to evaluate the potential for reuse and inﬁltration. It also illustrates the need for diﬀerent types of treatment before any recycling of the water. It can also be concluded that the present knowledge about the characteristics of grey wastewater (physical, chemical and biological constituents) is limited. The information available in the literature clearly shows that the focus has been on the content of oxygen consuming compounds (BOD and COD), nutrients and some microorganisms. A few studies have included measurements of heavy metals, while information about the presence and levels of speciﬁc XOCs is totally missing. A list of those XOCs that potentially could be present in grey wastewater was constructed based on product information and the knowledge available on the presence of XOCs in domestic wastewater. However, the number of compounds in this list exceeded 900 diﬀerent compounds, and that is why some priority criteria have to be used in order to select those XOCs that should be included in a monitoring program, for example. It is

suggested that the same criteria as used in environmental risk assessment of chemicals are applied, in order to assess the eﬀects on the environment of these substances. The number of published studies focusing on diﬀerent methods for reuse of grey wastewater (e.g., irrigation or indirect reuse by inﬁltration) is scarce. The health aspects and economics from this type of alternative wastewater handling have been examined but no environmental hazard identiﬁcation considering inﬁltration has been found. It has been shown that it can be reused for toilet ﬂushing without a health risk if it is treated prior to reuse. This study also stresses the need for a thorough characterisation of grey wastewater and source evaluation of the possible sources of pollutants in grey wastewater, before reuse, in order to be able to establish the proper treatment method. Microbiological contamination may pose a serious threat to health if grey wastewater comes into contact with humans, for example by toilet ﬂushing. The content of XOCs and salts is to be considered if the grey wastewater is to be reused for irrigation or inﬁltration since, untreated, it can potentially be toxic to plants and may pollute the groundwater.

Acknowledgements The authors wish to acknowledge Dr. Ann Marie Eilersen for valuable comments on the manuscript. Financial support from the Danish Environmental Protection Agency and the Technical University of Denmark is also acknowledged.

References Albrechtsen, H. -J. (1998). Water consumption in residences. Microbiological investigations of rain water and greywater reuse systems. Miljøstyrelsen (Miljø- og Energiministeriet) og Boligministeriet. ISBN 87-985613-9-1 [In Danish]. Almeida, M. C., Butler, D., & Friedler, E. (1999). At-source domestic wastewater quality. Urban Water, 1, 49–55. Burrows, W. D., Schmidt, M. O., Carnevale, R. M., & Schaub, S. A. (1991). Nonpotable reuse: Development of health criteria and technologies for shower water recycle. Water Science Technology, 24(9), 81–88. Christova-Boal, D., Eden, R. E., & McFarlane, S. (1996). An investigation into greywater reuse for urban residential properties. Desalination, 106, 391–397. Crook, J., & Surampalli, R. Y. (1996). Water reclamation and reuse criteria in the US. Water Science Technology, 33(10–11), 451–462. Dixon, A. M., Butler, D., & Fewkes, A. (1999a). Guidelines for greywater reuse: Health issues. J. CIWEM, 13, 322–326. Dixon, A., Butler, D., Fewkes, A., & Robinson, M. (1999b). Measurement and modelling of quality changes in stored untreated grey water. Urban Water, 1, 293–306.

E. Eriksson et al. / Urban Water 4 (2002) 85–104 Feachem, R. G., Bradley, D. J., Garelick, H., & Mara, D. D. (1980). Appropriate technology for water supply and sanitation. Health aspects of excreta and sullage management: A state of the art review (Vol. 3). The world Bank: Transportation, Water and Telecommunications Department. Feachem, R. G., Bradley, D. J., Garelick, H., & Mara, D. D. (1983). Sanitation and disease. Health aspects of excreta and wastewater management (pp. 16–21). The World Bank. Fittschen, I., & Niemczynowicz, J. (1997). Experiences with dry sanitation and greywater treatment in the eco-village Toarp, Sweden. Water Science Technology, 35(9), 161–170. Gerba, C. P., Straub, T. M., Rose, J. B., Karpiscak, M. M., Foster, K. E., & Brittain, R. G. (1995). Water quality of graywater treatment system. Water Research, 31(1), 109–116. Gregory, J. D., Lugg, R., & Sanders, B. (1996). Revision of the national reclaimed water guidelines. Desalination, 106, 263–268. G€ unther, F. (2000). Wastewater treatment by greywater separation: Outline for a biologically based greywater puriﬁcation plant in Sweden. Ecological Engineering, 15, 139–146. Hagebro, C., & Andersen, T., (1990). Miljøfremmende, organiske stoﬀer i kommunalt spildevand. Miljøprojekt nr. 127, Miljø- og Energiministeriet and Cowiconsult. ISBN 87-503-8317-5 [In Danish]. Hansen, A. M., & Kjellerup, M., (1994). Vandbesparende foranstaltninger. Teknisk Forlag, Copenhagen, ISBN 87-571-1435-9 [References in the text, In Danish]. Hargelius, K., Holmstrand, O., & Karlsson, L. (1995). Hush allsspillvatten Framtagande av nya schablonv€arden f€ or BDT-vatten. In Vad inneh aller avlopp fr an hush all? N€aring och metaller i urin och fekalier samt i disk-, tv€ att-, bad- & duschvatten. Stockholm: Swedish EPA (Naturv ardsverket). Henze, M., Harremo€es, P., la Cour Jansen, J., & Arvin, E. (2001). Wastewater treatment biological and chemical processes (3rd ed.). Berlin: Springer. Hypes, W. D. (1974). Characterization of typical household grey water. In J. H. T. Winneberger (Ed.), Manual of grey water treatment practice (pp. 79–88). Jenkins, D. (1998). The eﬀect of reformulation of household powder laundry detergents on their contribution to heavy metals levels in wastewater. Water Environment Research, 70(5), 893–980. Jeppesen, B. (1993). Domestic greywater reuse: Preliminary evaluation. Urban Water Research Association of Australia, ISBN 1 875298 61 4. Jeppesen, B. (1996). Model guidelines for domestic greywater reuse for Australia – Research report no. 107. Urban Water Research Association of Australia (UWRAA): Brisbane City Council. ISBN 1-876088-06-0. Jepsen, S.-E., & Gr€ uttner, H. (1997). Miljøfremmende stoﬀer i husholdningsspildevand. Miljøprojekt nr. 357, Miljø- og Energiministeriet. ISBN 87-7810-776-8 [In Danish]. Karlstr€ om, U., & Svensson, S. (1995). Milj€okriterier – F€or tv€attmedel. The Swedish Society for Nature Conservation [In Swedish]. Karpiscak, M. M., Foster, K. E., & Schmidt, N. (1990). Residential water conservation: Casa Del Agua. Water Research, 26(6), 939– 948. Laak, R. (1974). Relative pollution strengths of undiluted waste materials discharged in households and the dilution waters used for each. In J. H. T. Winneberger (Ed.), Manual of grey water treatment practice (pp. 68–78). Ann Arbor, MI: Ann Arbor Science. Mara, D. D., & Feachem, R. G. (1999). Water and excreta related diseases: Unitary environmental classiﬁcation. Journal of Environmental Engineering, 125(4), 334–339. Mattson, J., Averg ard, I., & Robinson, P. (1991). Priority pollutants, heavy metals and main constituents in the domestic sewage from two residential areas in Gothenburg. Vatten, 47, 204–211 [In Swedish].

103

National Center of Health Statistics. (2000). National Vital Statistics Reports (USA) 48 (9). National Consumer Agency in Denmark. (1999). Publication ‘‘Vaskeog rengøringsmidler’’. Available from http://www.fs.dk/skole/vaskeren2.htm [In Danish]. Naturv ardsverket (1992). Klororganiska f€oreningar fr an disk- och blekmedel? En f€ors€oksstudie. Report 4009, Naturv ardsverket, ISBN 91-620-4009-X [In Swedish]. Nolde, E. (1999). Greywater reuse systems for toilet ﬂushing in multistorey buildings – over ten years experience in Berlin. Urban Water, 1, 275–284. Okun, D. A. (1997). Distributing reclaimed water through dual systems. American Water Works Association Journal, 89(11), 52–64. Otterpohl, R., Albold, A., & Olgenburg, M. (1999). Sources control in urban sanitation and waste management: Ten systems with reuse of resources. Water Science Technology, 39(5), 153–160. Paxeus, N., & Schr€ oder, H. F. (1996). Screening for non-regulated organic compounds in municipal wastewater in G€ oteborg, Sweden. Water Science Technology, 33(6), 9–15. Paxeus, N. (1996). Organic pollutants in the eﬄuents in large wastewater treatment plants in Sweden. Water Research, 30(5), 1115–1122. Paxeus, N., Robinson, P., & Balmer, P. (1992). Study of organic pollutants in municipal wastewater in G€ oteborg, Sweden. Water Science Technology, 25(11), 249–256. Pedersen, A.R., & Madsen, T. (1998). H arshampo og -balsam – Fiskerne kan ikke lide skummet nr. 1 1998. R ad & Resultater: Forbrugerstyrelsen [In Danish]. Puchta, R., Krings, P., & Sandk€ uhler, P. (1993). A new generation of softeners. Tenside Surface Detergents, 30(3), 186–191. Rose, J. B., Sun, G., Gerba, C. P., & Sinclair, N. A. (1991). Microbial quality and persistence of enteric pathogens in graywater from various household sources. Water Research, 25(1), 37–42. Santala, E., Uotila, J., Zaitsev, G., Alasiurua, R., Tikka, R., & Tengvall, J. (1998). Microbiological greywater treatment and recycling in an apartment building. In AWT98 – Advanced Wastewater Treatment, Recycling and Reuse: Milan, 14–16 September, 1998 (pp. 319–324). Sheikh, B. (1993). The city of Los Angeles gray water pilot project shows safe use of gray water is possible. In Water resources planning management and urban water resources (pp. 678–681). New York, USA: ASCE. Shin, H.-S., Lee, S.-M., Seo, I.-S., Kim, G.-O., Lim, K.-H., & Song, J.S. (1998). Pilot-scale SBR and MF operation for the removal of organic and nitrogen compounds from greywater. Water Science Technology, 38(6), 79–88. Siegrist, H., Witt, M., & Boyle, W. C. (1976). Characteristics of rural household wastewater. Journal of the Environmental Engineering Division, 102(EE3), 533–548. Statistics Denmark. (1999). Population size in 1998. Available from http://www.dst.dk/ [In Danish]. Statistics Finland. (2000). Available from http://www.stat.ﬁ/tk/tp/ tasku/taskut_ru.html [In Swedish]. Statistics Norway. (2000). Available from http://www.ssb.no/emner/ 02/aktuell_befolkning/9912/ab9912.pdf [In Norwegian]. Statistics Sweden. (1999). Population size in 1998. http://www.scb.se/ [In Swedish]. Stenstr€ om, T.-A. (1996). Sjukdomsframkallande mikroorganismer i avloppssystem – riskv€ardering av traditionella och alternativa avloppsl€osningar. Swedish EPA, the National Board of Health and Welfare and the Swedish Institute for Infectious Disease Control. Report no. 4683. ISBN 91-620-4683-7 [In Swedish]. Stenstr€ om, T. -A., Hoﬀner, S., & Br€ omssen, U. (1980). Reduktion av bakterier och virus vid avloppsvatteninﬁltration i mark – en kunskapssammanst€allning. Swedish EPA, PM 1329 [In Swedish]. Surendran, S., & Wheatley, A. D. (1998). Grey-water reclamation for non-potable re-use. J. CIWEM, 12, 406–413.

104

E. Eriksson et al. / Urban Water 4 (2002) 85–104

Swedish Society for Nature Conservation. (2000). Available from http://www.snf.se/pdf/bmv/rap-bmv-surfactants 2000.pdf. Van Leeuwen, C. J., & Hermens, J. L. M. (Eds.). (1995) Risk assessment of chemicals: An introduction. Dordrecht: Kluwer Academic Publishers. Wilkie, P. J., Hatzimihalis, G., Koutouﬁdes, P., & Connor, M. A. (1996). The contribution of domestic sources to levels of key

organic and inorganic pollutants in sewage: The case of Melbourne, Australia. Water Science Technology, 34(3–4), 63–70. World Health Organization. (1989). Health guidelines for the use of wastewater in agriculture and aquaculture. Technical Report Series 778, ISSN 0512-3054.