Wastewater Workshop in Nairobi 29-th August till 03-rd September 2011 Sewer Systems Dr.- Ing. Rainer-Werner Abendt Nuremberg Contact: rainer.abendt@gmx.de Rainer Abendt ® Sewer Systems A Recap of the previous module indicated that:Sewage purification systems are necessary for health. Because supply of clean water to the population is indispensable for health provision. (National Water Services) But sewage systems are also important for protection of groundwater or river water. Why? Because we need river or ground water to produce drinking water ! Rainer Abendt ® Sewer Systems Sources of raw water in Bavaria Millions. m³/yr % value groundwater from wells 700.7 74,8 groundwater from springs 163.8 17,5 bank filtrate, recharged groundwater 48.3 5,1 surface water 24.2 2,6 937.1 100 Total Rainer Abendt ® Sewer Systems 1 Effluent Standards (emission) 2 Water Quality Standards (imission) 3 Education Standards: labours and academic 4 4 Health and Safety Standards 3 1 2 Rainer Abendt ® Sewer Systems First step! Without Stormwater Drainage Evolution in sewer network: - By-laws Urban area Treatment plant -auslässe Evolution of water crowd: Legal Orders - Sewer construction Evolution of Water quality: - Sewer operation Rainer Abendt ® Sewer Systems Or First step! With separate Stormwater Drainage Evolution in sewer network: - By-laws -auslässe Legal Orders Effluent in a river Urban area Treatment plant -auslässe Evolution of water crowd: Legal Orders - Sewer construction Evolution of Water quality: - Sewer operation Rainer Abendt ® Sewer Systems Or First step! Storm- and Wastwater mixed Evolution in sewer network: - By-laws -auslässe Urban area Legal Orders Treatment plant Evolution of water crowd: - Sewer construction Stormwater Effluents Are the stormwater drains connected to the trunk sewer? If not, where does the stormwater drain to? -auslässe Evolution of Water quality: Legal Orders - Sewer operation Rainer Abendt ® Sewer Systems Administration: Finances; By-laws: Personnel Connection approval; Industrial monitoring; Cost covering Wastewater disposal (Discharge and treatment) Sewer operation: Sewer construction: General drainage; Sewer network expansion; Maintenance, repair, operation/control of storage space and outlets (provisions under water law) Rainer Abendt ® Sewer Systems • Pipe Varieties in Nuremberg, Germany. These are examples of types of pipes needed for various transmission works In selecting a pipe material for sewer service, the design engineer must evaluate standards for materials, products and systems The standards must meet international specifications and must have passed Proficiency Testing Programs for quality assurance. Rainer Abendt ® Sewer Systems Technical Standards of Materials Product &Testing Standards guarantee quality. Check the:pipe diameter Pipe Material Pipe thickness Rainer Abendt ® First WASPA Annual International DENConference = Technical European Norms 8-9th September 2011, KICC Grounds, Nairobi, Kenya Free trade Rainer Abendt ® Sewer Systems Examples of Standards Quality of on Water Materials: CEN TC 155 „Plastics piping systems“ “ CEN TC 163 „Sanitary appliances “ CEN TC 164 „Water supply “ CEN TC 165 „Waste Water Engineering“ CEN TC 203 „Cast iron pipes “ CEN TC 208 „Elastomeric seals“ CEN TC 230 „Water analysis “ CEN TC 308 „Characterization of sludges“ Rainer Abendt ® Sewer Systems Example: ‘Visual inspection coding system, Rainer Abendt ® Sewer Systems Wastewater types (QWW): 1. Domestic wastewater (QD) such as: shower water swimming pool water flushing water faecal water 2. Commercial and/or industrial wastewater (QInd) such as: production water treatment water cooling water 3. Infiltration water (QIW) 4. Stormwater (rainfall) (QR) 5. Melt water Daily amount of wastewater, normal in Europe: average: 125 - 200 l / (per individuaI per day) frequently: > 300 l / (per individual per day) due to increased amounts of infiltration water (QIW) Rainer Abendt ® Sewer Systems Parameters in Wastewater pollution (raw sewage): Inhabitant-related loads in raw wastewater BOD5 : 60 g/(per Individual per day) COD: 120 g/(per Individual per day) filterable solids: 70 g/(per individual per day) Ptot: 1.8 g/(per individual per day) Ntot: 11 g/(per individual per day) Ntot in raw wastewater mainly as TKN TKN (Total Kjeldahl Nitrogen): Norg + (NH4+ - N) undissolved matter: 30 % dissolved matter: 70 % Rainer Abendt ® Sewer Systems Wastewater pollution (raw sewage): Concentrations of minimum parameters in domestic raw wastewater: BOD5: 200 - 400 mg/l COD: 400 - 800 mg/l Ptot: 5 - 12 mg/l Ntot: 30 - 75 mg/l Rainer Abendt ® Sewer Systems The wastewater discharged into the sewer system should not possess the following characteristics: 1. Free acids (pH values < 6.5) and strong lyes (pH > 8.5) 2. Salts in high concentrations 3. Strong poisons (toxic substances, e.g. Cu ions) 4. Oils and greases (mineral oils) 5. Hazardous and explosive gases (e.g. methane, petrol fumes) 6. Odorous substances (e.g. sulphides from leather processing) 7. Large quantities of suspended or heavy settleable solids 8. Radioactive substances (e.g. from hospitals) 9. High Temperatures (over 35 °C) 10. Heavy discoloration (e.g. from the textile processing industry) Rainer Abendt ® Sewer Systems The daily variation of waste water % Q [l/s] % QKW 200 190 180 170 160 Reserve für Regenwasser, QRW 150 Pipe capacity for stormwater 140 130 120 110 100 Wastewater 90 Schmutzwasser QSW 80 70 60 50 40 Infiltration Water 30 20 Fremdwasser QFW 10 0 t [h] 5.00 Rainer Abendt 9.00 13.00 17.00 21.00 1.00 5.00 ® Sewer Systems Cost Reduction: You can reduce your treatment costs, if you ensure non-soiled wastewater does reach the sewer network at all. In a mixed sewer net (rain and wastewater) you can reduce your costs by building a storm water tank at a quarter the distance from the start of the trunk sewer with a drain time of 10 to 15 minutes in the channel. Rainer Abendt ® Sewer Systems Sewer network of Nuremberg Treatment plants Sewer network Stormwater tank Rainer Abendt ® Sewer Systems Schematic profile Rainer Abendt ® Sewer Systems Diagram Rainer Abendt ® Sewer Systems Water quality of the river Rainer Abendt ® Why Sewage Purification ? Demands on water quality (Europe): COD BOD5 Ammonia Ntot Suspended Solid P tot Rainer Abendt ® Sewer Systems Administration Financial management Legal orders Personnel Evolution in sewer network: - By-laws Automatic monitoring Documentation ? Urban area Government control Product 1 „Clean Water" Treatment plant (Process system) Product 2 "Sludge" Evolution of water crowd: Legal orders - Sewer construction Demands on the sludge Evolution of Water quality: - Sewer operation Laboratory Secure disposal operating data Rainer Abendt ® Sewer Systems How then does a Treatment Plant look like ? Rainer Abendt ®