en m32 ecosan technologies water loop lecture 2006

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M3: Ecosan Systems and Technology Components M 3-2: Ecosan Technologies to Close the Water Loop Prof. Dr. Petter Jenssen, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences Dr. Johannes Heeb, International Ecological Engineering Society & seecon international Dr. Ken Gnanakan, ACTS Bangalore, India Katharina Conradin, seecon gmbh © 2006 seecon International gmbh DEMO-VERSION: LINKS TO EXTERNAL DOCUMENTS DO NOT WORK!

Credits: 

K. Conradin Materials included in this CD-ROM comprise materials from various organisations. The materials complied on this CD are freely available at the internet, following the open-source concept for capacity building and non-profit use, provided proper acknowledgement of the source is made. The publication of these materials on this CD-ROM does not alter any existing copyrights. Material published on this CD for the first time follows the same open-source concept for capacity building and non-profit use, with all rights remaining with the original authors / producing organisations. Therefore the user should please always give credit in citations to the original author, source and copyright holder. We thank all individuals and institutions that have provided information for this CD, especially the German Agency for Technical Cooperation GTZ, Ecosanres, Ecosan Norway, the International Water and Sanitation Centre IRC, the Stockholm Environment Institute SEI, the World Health Organisation WHO, the Hesperian Foundation, the Swedish International Development Cooperation Agency SIDA, the Department of Water and Sanitation in Developing Countries SANDEC of the Swiss Federal Institute of Aquatic Science and Technology, Sanitation by Communities SANIMAS, the Stockholm International Water Institute SIWI, the Water Supply & Sanitation Collaborative Council WSSCC, the World Water Assessment Programme of the UNESCO, the Tear Fund, Wateraid, and all others that have contributed in some way to this curriculum. We apologize in advance if references are missing or incorrect, and welcome feedback if errors are detected. We encourage all feedback on the composition and content of this curriculum. Please direct it either to johannes.heeb@seecon.ch or petter.jenssen@umb.no. Credits

Credits: 

Credits ecosan Curriculum - Credits Concept and ecosan expertise: Johannes Heeb, Petter D. Jenssen, Ken Gnanakan Compiling of Information: Katharina Conradin Layout: Katharina Conradin Photo Credits: Mostly Johannes Heeb & Katharina Conradin, otherwise as per credit. Text Credits: As per source indication. Financial support: Swiss Development Cooperation (SDC) How to obtain the curriculum material Free download of PDF tutorials: www.seecon.ch www.ecosan.no www.gtz.de/ecosan Order full curriculum CD: johannes.heeb@seecon.ch € 50 (€ 10 Developing Countries) petter.jenssen@umb.no Release: 1.0, March 2006, 1000 copies Feedback: Feedback regarding improvements, errors, experience of use etc. is welcome. Please notify the above email-addresses. Sources Copyright: Copyright of the individual sources lies with the authors or producing organizations. Copying is allowed as long as references are properly acknowledged.

Contents: 

Contents

Contents: 

Contents

Introduction: 

Introduction This module will explain how the water loop can be closed. As in the module before, source separation is a prerequisite. Greywater makes up for the largest volume of the generated “wastewater”, but contains the lowest share of nutrients and pathogens. Watering garden Recrea-tional water Ground-water recharge Filtration (membrane, sand) Biologi-cal Treat-ment Water (drinking water) Nutrient Energy Fertilizer (N, P, K) Soil amend-ment Anaerobic treat-ment (biogas) Aerobic treat-ment (composting) Grey-water Black-water Organic waste

Source Separated Wastewater Collection/Treatment Systems: 

Source Separated Wastewater Collection/Treatment Systems P. Jenssen

Greywater Volumes: 

Greywater Volumes Greywater amounts per person can vary greatly. Here: range from 81 -133 l/person/day Source: Jenssen (8) Source: (8)

Greywater Characteristics: 

Greywater Characteristics Greywater volumes can constitutes >90% Limited amount of nutrients in greywater, depending on use. Phosphate content: depending on whether detergents contain phosphate or not Source: Vinnerås (2) Source: (9)

Greywater Characteristics: 

Greywater Characteristics NUTRIENTS IN GREYWATER normally low levels of nutrients high concentrations of phosphorous possible (washing and dish-washing detergents) P-free detergents available detergents containing phosphorous banned in some countries for water protection SUSPENDED SOLIDS AND BIODEGRADABLE ORGANIC COMPOUNDS Composition of greywater varies greatly  reflects lifestyle of residents Greywater often contains high concentrations of easily degradable organic material (fat, oil and other organic substances from cooking, Separate collection of cooking oil for conversion to biodiesel Cooking oil can be added directly to anaerobic digesters  biogas. Greywater Treatment in Luebeck, Germany

Greywater Characteristics: 

Greywater Characteristics PATHOGENS Generally low proportion of pathogens Faecal contamination: showering, washing of clothes and diapers Indicator bacteria such as faecal coliforms may multiply in the septic tank  overestimation of risk possible Levels of potential pathogens in different waters. Levels of pathogens in the untreated waters are based on measured faecal load to greywater in Vibyåsen, Sweden, compared to the faecal contamination in normal mixed wastewater. Source: Ridderstople (3) Mixed wastewater, untreated Mixed wastewater, treated in advanced WWTP Greywater, untreated Greywater, treated in vertical soil filter bed

Greywater Characteristics: 

Greywater Characteristics METALS AND OTHER TOXIC POLLUTANTS content of metals and organic pollutants in greywater is generally low  increase by addition of hazardous substances Levels of metals: approximately same as in mixed wastewater from a household, Origin: water itself, corrosion of the pipe system and from dust, cutlery, dyes and shampoos etc. Organic Pollutants: Most organic pollutants in the wastewater are found in the greywater fraction: similar level as mixed wastewater Origin: household chemicals, shampoos, perfumes, preservatives, dyes and cleaners Content of metals and organic pollutants in greywater is heavily affected by human behaviour! Source: (3)

Greywater: Source Control: 

Greywater: Source Control Managing greywater: attention to the composition of soaps, cleansers and other household chemicals. Main criteria for sizing of greywater system: Hydraulic load load of easily degradable organic matters and BOD Reducing these parameters gives more cost efficient and volume- and area-saving solutions. Source control includes: water-saving equipment (taps, showerheads) BOD load: controlled use ofdetergents, shampoos, soaps, controlled disposal of grease / oil. Removing of all larger particles: Use filtes and screens Drawing: Per Hardestam, Karlstad Reklam AB (Source: 3) Source: (3)

Greywater Treatment Options: 

Greywater Treatment Options Here: Focus on natural systems: soil infiltration, constructed wetlands, ponds: small energy cost no chemicals require larger areas than the conventional systems Source: (9) Constructed Wetlands Activated Sludge Treatment

Greywater Treatment Options: 

Greywater Treatment Options

Greywater Treatment Options: 

Greywater Treatment Options lower hygienic risk a environmental problem than mixed wastewater large amounts of easily degradable organic matter Anaerobic conditions  smell  primary target: remove organic compounds secondary treatment target reduce levels of pathogens reduce levels of organic pollutants and heavy metals.  important if used for irrigation

Pretreatment: 

Pretreatment

Pretreatment: 

Pretreatment  to avoid clogging of the subsequent treatment system solid-liquid separation by gravity, flotation, screens septic tanks (most common), settling tanks, ponds, filter systems such as filter bags. Small systems: direct use of greywater possible (e.g. mulch bed) Source: Adapted from (29)

Drip irrigation: 

Drip irrigation

Drip Irrigation: 

Drip Irrigation long, flexible tubing with engineered openings or emitters. to drip at slow rate into the surrounding soil vegetation can also adsorb the nutrients Vegetation helps to clean greywater efficient use of water.  Source: Adapted from (29)

Soil Infiltration: 

Soil Infiltration

Soil Infiltration: 

Soil Infiltration After leaving the septic tank/pre-treatment unit the effluent is distributed to the soil through open ponds or shallow trenches or infiltration basin. Efficient way of treatment Infiltration in open basins/ponds (above) and in buried shallow trenches (below) the percolation down to the groundwater and subsequent flow towards a stream is indicated.

Soil Infiltration: 

water percolates down through an unsaturated zone to the groundwater (saturated zone). Most of the treatment: unsaturated zone Size according to local soil conditions! Careful design necessary: systems may endanger groundwater quality. Suitable sites: deep, well-drained, well-developed, medium-textured soils Impermeable soils, shallow rock, shallow water tables, or very permeable soils such as coarse sand or gravely soils are considered unsuitable sites  special design necessary Soil Infiltration Trench for Soil Infiltration Source: Adapted from (29)

Mound Systems: 

Mound Systems

Mound Systems: 

Mound Systems Similar to soil infiltration technique when existing soil is unsuitable for greywater disposal layer of soil on top of which the sand mound is built, is still biologically and chemically active  helps in treatment

Sand Filters: 

Sand Filters P. Jenssen

Sand Filters: 

Sand Filters well known method for wastewater and greywater purification planted sandfilter: often termed vertical flow wetlands, Vertical water flow Plants: help to avoid clogging, otherwise not much difference between planted and unplanted systems. P. Jenssen

Constructed Wetland: 

Constructed Wetland P. Jenssen

Constructed Wetland: 

Constructed Wetland Constructed wetlands: Artificial shallow ponds vegetated with macrophytes Often: subsurface flow constructed wetlands Porous media: sand, gravel, light weight aggregate, crushed brick etc. Fine grained soils: not suited (low hydraulic conductivity) Subsurface Flow Constructed Wetland for greywater treatment. Ecological Settlement, Luebeck Flintenbreite, Germany

Constructed Wetland: 

Constructed Wetland  Geometry: based on hydraulic calculations Cold climate: pre-treatment is recommended deeper systems Warmer climate: 0.4 – 0.6 m deep systems common P. Jenssen P. Jenssen Constructed Wetland in Ås, Norway, in the summer and in the winter, an area of 2 m2 per Student is needed (Total 48 Students)

Constructed Wetland: 

Constructed Wetland Constructed wetlands: generally good reduction of BOD and total nitrogen Phosphorus removal: dependent on the phosphorus sorption capacity of the porous media good pathogen removal In warm climates: possible without pretreatment biofilter. A subsurface flow wetland with and without integrated biofilter (14) P. Jenssen

Ponds: 

Ponds P. Jenssen

Ponds: 

Ponds Source: Adapted from (29) Ponds: developed for combined wastewater also well suited for greywater treatment shallow man-made basins  wastewater flows  retention time of several days effluent is discharged low in BOD Nitrogen reduction; 70-90% Phosphorus removal 30-45% Very robust design Limiting factors: size

Biofilters: 

Biofilters P. Jenssen

Biofilters: 

Biofilters 0,6m Jets LWA Diameter 2,5 mm Surface area > 5000m2/m3 Biofilter: covered by a compartment which facilitates spraying of the greywater (septic tank effluent) over the biofilter surface. standard depth of 60 cm grain size within the range 2 – 10 mm Filling material: light weight aggregate, gravel etc. biofilm develops: reduction of BOD and pathogens. Clogging: has not been observed uniform distribution of the liquid is important

Biofilters: 

Biofilters Pretreatment biofilter Horizontal subsurface flow wetland filter Septic tank Pump/siphon Level control & sampling port

Conventional Biological Treatment: 

Conventional Biological Treatment P. Jenssen

Conventional Biological Treatment: 

Conventional Biological Treatment P. Jenssen Conventional biological treatment (enhanced) active sludge treatment fixed film systems: trickling filters or rotating biological contactors Advantage: compact setting (i.e. in densely populated urban settings) Efficient reduction of organic matter Bacteria and virus requirement: succeeded other methods such as sand filter, subsurface flow constructed wetland Chemical treatment also possible Active Sludge Treatment aeration concrete: greywater mixed with recycled sludge containing active aerobic bacteria Sludge decanting in attached tank --> returned to the aeration tank. Pretreatment necessary Assumption: low treatment efficiency due to low nutrient content, but probably good for heavily loaded greywater

Conventional Biological Treatment: 

Conventional Biological Treatment RBC – Rotating Biological Contactors Series of closely spaced circular discs high surface area for the growth of micro-organisms discs submerged about 50% and rotate slowly aerobic biological film alternatively exposed to air or wastewater Dead biofilm drops  sludge. Source: www.wee-engineer.com Source: Adapted from (29)

Conventional Biological Treatment: 

Conventional Biological Treatment Trickling Filter concrete column filled with a coarse carrier material (crushed rock, slag, gravel or plastic modules) conventionally 1 to 3 m deep. Even distribution of wastewater  bio-film develops micro-organisms of the bio-film degrade wastewater pollutants Aeration from the bottom Source: (24)

Chemical Treatment: 

Chemical Treatment P. Jenssen

Chemical Treatment: 

Chemical Treatment Chemical treatment primarily used to reduce phosphorus, but also organic matter chemical precipitation also reduces virus and bacteria. Compact systems (suitable for urban areas) post treatment in a sandfilter or wetland

Membrane Filtration: 

Membrane Filtration P. Jenssen

Membrane Filtration: 

Membrane Filtration semi-permeable membrane + osmotic or lower pressure dissolved solids or other constituents captured as the retenate semi-permeable membrane + osmotic or lower pressure dissolved solids or other constituents captured as the retenate Retaining of different particle sizes: Microfiltration Ultrafiltration nanofiltration reverse osmosis Use in greywater treatment: tertiary removal of dissolved salts, organic compounds, phosphorus, colloidal and suspended solids, and human pathogens, including bacteria, protozoan cysts, and viruses

Membrane Filtration: 

Membrane Filtration P. Jenssen

Reuse: 

Reuse Reuse of all greywater makes water savings exceeing 90% possible when a water efficient toilet is used (1). Local discharge into water bodies: where sufficient water is available If high quality effluent is reached Use in Irrigation: closes the water cycle Local in garden or big scale

Reuse: 

Reuse Inhouse Use: Inhouse uses: especially where no drinking water quality is required, (toilet flushing, clothes washing, or showering) Reduces consumption of drinking water Drinking water quality possible with reversed osmosis Groundwater Recharge Where groundwater table has been lowered

Complete System for One Household: 

Complete System for One Household Biofilter Septic tank Blackwater holding tank Pump chamber

Conclusion: 

Conclusion P. Jenssen Pump sump Final discharge 1st chamber of oil and grease trap Pilot project Hui Sing Garden Greywater treatment (Malaysia) Three water samples from the Hui Sing Garden Greywater Treatment, working with a constructed wetland. The picture visualises the treatment efficiency.

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END OF MODULE M3-2 Prof. Dr. Petter Jenssen, Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences Dr. Johannes Heeb, International Ecological Engineering Society & seecon international Dr. Ken Gnanakan, ACTS Bangalore, India Katharina Conradin, seecon gmbh © 2006 seecon International gmbh Click here to go to the further information part BACK TO THE MAIN MENU

++ References: 

++ References Alsén, K.W. & Jenssen, P. D. (2005): Ecological Sanitation – for mankind and nature. Norwegian University of Life Sciences, As, Norway Vinnerås, B. (2002): Possibilities for sustainable nutrient recycling by faecal separation combined with urine diversion. Agraria 353 - Doctoral thesis. Swedish University of Agricultural Sciences, Uppsala. - In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report 2004-4. Ecosanres, SEI. Stenström, Th.-A. (1996): Sjukdomsframkallande mikroorganismer i avloppssystem. NV, Socialstyrelsen och Smittskyddsinstitutet, Rapport 4683 In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report 2004-4. Ecosanres, SEI. SWEP (1982) Specifika föroreningar vid kommunal avloppsrening, Sedisk EPA, PM1964. (In Swedish) - In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report 2004-4. Ecosanres, SEI. Vinnerås, B. (2001): Faecal separation and urine diversion for nutrient management of household biodegradable waste and waste water. SLU. Report 244. In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report 2004-4. Ecosanres, SEI. Eriksson, Helena (2002): Potential and problems related to reuse of water in households, Env.&Resources DTU, Techn. Univ. of Denmark, Ph.D Thesis. In: Ridderstolpe, P. (2004): Introduction to Greywater Management. Ecosanres Publication Series, Report 2004-4. Ecosanres, SEI. Jenssen, P.D. (2001): ”Design and performance of ecological sanitation systems in Norway”, Paper at The First International Conference on Ecological Sanitation, Nanning, China. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. European Environment Agency EPA (2005): Indicator: Biochemical oxygen demand in rivers. Available at: http://themes.eea.eu.int/Specific_media/water/indicators/bod/index_html (Accessed 28.10.2005) Siegrist, R.L., E.J. Tyler and P.D. Jenssen (2000): Design and performance of onsite wastewater soil absorption systems. Report presented at National Research Needs Conference Risk-Based Decision Making for Onsite Wastewater Treatment, St. Louis, Missouri,19-20 May 2000. USEPA. – In: (29) WHO (2006). Jenssen, P.D. and R.L. Siegrist (1990): Technology assessment of wastewater treatment by soil infiltration systems. Wat. Sci. Tech., 22 (3/4) pp. 83-92. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover.

++ References: 

++ References Engelbert, E. & Regan, W.R. (no year): A Lexicon for Alternate On-Site Wastewater Treatment Systems. College of Agricultural Sciences, U.S. Department of Agriculture, and Pennsylvania Counties. Available at: www.abe.psu.edu/extension/factsheets/f/F170.pdf Accessed 14.12.2005 Crites, R., and G. Tchobanoglous (1998): Small and decentralized wastewater management systems. McGraw-Hill. Jenssen P.D. and A. Heistad (2000): Naturbaserte avløpsløsninger. Student text. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Aas Norway (in Norwegian). – In: (29) WHO (2006). Jenssen P.D., T. Mæhlum, T. Krogstad and Lasse Vråle (2005): Treatment Performance of Multistage Constructed Wetlands for Wastewater Treatment in Cold Climate. Accepted in the Journal of Environmental Science and Health. Vol 40 (6-7) 1343-1353. – In: (29) WHO (2006). Zhu, T. (1998). Phosphorus and nitrogen removal in light-weight aggregate (LWA) constructed wetlands and intermittent filter systems. PhD Theses 1997:16, The Agricultural University of Norway. – In: (29) WHO (2006). Jenssen, P. D. and L. Vråle (2004): Greywater treatment in combined biofilter/constructed wetlands in cold climate In: C. Werner et al. (eds.). Ecosan – closing the loop. Proc. 2nd int. symp. ecological sanitation, Lübeck Apr. 7-11. 2003, GTZ, Germany, pp:875-881. – In: (29) WHO (2006). Reed, S.C. (1993) Subsurface flow constructed wetlands – a technology assessment. USEPA report 832-R-93-001. – In: (29) WHO (2006). Mara, DD (1998): Design Manual for Waste Stabilisation Ponds in Mediterranean Countries, Lagoon Technology International Ltd., England. – In: (29) WHO (2006). Ottoson, J. and T. A. Stenström (2002): Faecal contamination of greywater and associated microbial risks. Water Research, 37, 645-655. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. Heistad, A., P.D. Jenssen and A.S. Frydenlund (2001): A new combined distribution and pretreatment unit for wastewater soil infiltration systems. In K. Mancl (ed.) Onsite wastewater treatment. Proc. Ninth Int. Conf. On Individual and Small Community Sewage Systems, ASAE. Nolde, E. 1996. Greywater reuse in households – experience form Germany. Environmental Research Forum Vols. 5-6:55-64. Transtec Publ., Switzerland. In: Jenssen, P.D., Greatorex, J.M, & Warner, W. S. (2004): Sustainable Wastewater Management in Urban Areas. = Kapitel 4. Kurs WH33, Konzeption Dezentralisierter Abwasserreinigung und Stoffstrommanagement. Universität Hannover. SANIMAS (2005): Informed Choice Catalogue. PP-Presentation. BORDA, AUSAID.

++ References: 

++ References Noah, M. 2001. Onsite Treatment Options: Matching the system to the site. Small Flows Quarterly, 2(1), Winter. In: Engelbert, E. & Regan, W.R. (no year): A Lexicon for Alternate On-Site Wastewater Treatment Systems. College of Agricultural Sciences, U.S. Department of Agriculture, and Pennsylvania Counties. Available at: www.abe.psu.edu/extension/factsheets/f/F170.pdf Accessed 14.12.2005 Reardon, R.D.: Clearing the Water about Wastewater Treatment with Membranes. CDM Viewpoint Archive. Available at: http://www.cdm.com/Ideas@Work/Viewpoint/Treating+Wastewater+with+Membranes.htm?bc=archive (Accessed 1.11.2005) Westlie, L. (1997): Treatment of greywater from households and cottages in compact filters. (Rensing av gråvann i kompakte filtre for boliger og hytter). Report from the NAT-program, no. 140/97. Norwegian Centre for Soil and Environmental Research, 1432 Aas Norway (In Norwegian). – In: (29) WHO (2006). Jenssen, P. D. (2003): Improving water and sanitation by decentralized groundwater supply and infiltration. PP-Presentation. Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences. WHO (2006). Guidelines for the safe use of wastewater, excreta and greywater. Volume 4: Excreta and greywater use in agriculture. Draft version. Zhang Y, Dube MA, McLean DD, Kates M., (2003): ”Biodiesel production from waste cooking oil: 1. Process design and technological assessment”. Bioresour Technol. 2003 Aug; 89 (1): 1-16. Jenssen P. D. and Krogstad T. (2002) Design of constructed wetlands using phosphorus sorbing lightweight aggregate (LWA). In: Constructed wetlands for wastewater treatment in cold climates. Ü. Mander and P. D. Jenssen (eds.) Advances in Ecological Sciences, 11, pp: 259 – 271, WIT Press. Jenssen P. D., Mæhlum T. and Krogstad T. (1993). Potential use of constructed wetlands for wastewater treatment in northern environments. Wat. Sci.Tech., 28 (10), 149-157. Heistad A., Vråle L., Paruch A. M., Adam K., Jenssen P. D. (2005). A high performance compact wastewater treatment system using lightweight aggregate In: Nutrient Management in Wastewater Treatment Processes and Recycle Streams, Proceedings of IWA Specialized International Conference, Krakow * Poland, pp. 959-966. Ottoson J. (2003). Hygiene aspects of greywater reuse. Licenciate Thesis. Royal Swedish Institute of Technology, Swedish Institute for Infectious Disease Control. TRITA-LWC LIC 2011. Browne W. and P.D. Jenssen (2005) Exceeding tertiary standards with a pond/reed bed system in Norway. Water Science & Technology Vol 51 No 9 pp 299-306. Ødegaard, H: 1992. Fjerning av næringsstoffer ved Rensing av Avløpsvann. Tapir Forlag, 80p.

++ Abbreviations: 

++ Abbreviations BOD Biochemical Oxygen Demand RBC Rotating Biological Contactors SS Suspended Solids STE Septic Tank Effluent WSP Wastewater Stabilization Ponds

++ Glossary: Greywater: 

++ Glossary: Greywater Greywater is only slightly polluted wastewaters from dishwashing, showers, laundry machines, water from sinks etc. Greywater makes up for the largest share of wastewater. Yellow water is either urine diluted with flushwater or pure urine. Urine contains most of the nutrients we excrete again, but only has a very low, if at all, pathogen count. However, we also excrete micro-pollutants or endocrine substances through urine. Brownwater refers to faeces mixed with (flushing) water, but no urine. Most of the pathogens and a high proportion but rather little of the nutrients are contained here. Blackwater is urine and faeces mixed with or without domestic wastewater from showers, washing machines, sinks etc. GREYWATER

++ Glossary: Biochemical Oxygen Demand (BOD): 

++ Glossary: Biochemical Oxygen Demand (BOD) Biochemical oxygen demand (BOD) is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river’s biodiversity. High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated wastewater high nitrate levels, which trigger high plant growth Both result in higher amounts of organic matter in the river. When this matter decays, the microbiological activity uses up the oxygen. Biochemical oxygen demand is therefore one of the main parameters used in the Urban Wastewater Treatment Directive for controlling discharges. Unsurprisingly, large rivers – where wastewater plants are more likely to be located – register higher levels of oxygen demand than smaller rivers. Improvements in wastewater management causes biochemical oxygen demand to fall in all sizes of rivers (10). BIOCHEMICAL OXYGEN DEMAND