Sludge treatment through composting prior to reuse – the alexandria experience

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At site 9 we have consistently composted and achieved a high compost quality in a safe and cost effective manner

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Sludge treatment through composting prior to reuse – the alexandria experience

  1. 1. Improving the Capacity of the Holding Company for Water and Waste Water (HCWW) - Ministry of Housing, Utilities and Urban Development, Egypt (EuropeAid/129937/D/SER/EG) Holding Company Capacity Improvement (PAO-SAAP / European Union) CHCI Dr.Helalley Abdelhady Helalley Holding Company Capacity Improvement (HCCI)
  2. 2. Project Location
  3. 3. 3 Scum/Screenings Leachate Evaporation Ponds Storage Area for Spoil Material Dedicated Land Disposal (DLD) Area Compost Area Fuel Station Guard House Administration BuildingVehicle Wash Sludge and Grit Receiving Area Sludge Wash Area Dedicated Land Disposal (DLD) Area Spoil Material Storage Area Scum/Screenings Trenches
  4. 4. Grit treatment Area Emergency Composting Area
  5. 5. Sludge composted at site 9 is mechanically dewatered sludge from the East and West treatment plants and some other smaller treatment facilities. Total quantity processed on average: 2000 m3/d
  6. 6. 6 Sludge mechanical dewatering through belt presses
  7. 7. 7
  8. 8. Receiving area : sludge unloading into spreaders
  9. 9. Sludge spreading on the soil surface in a layer of 65 mm thickness. sludge application rate: 10-30 kg/m2
  10. 10. Mixing sludge with soil Previous sludge disposal system Dedicated Land Disposal (DLD) Disking operation
  11. 11. Mixing sludge with soil Land disposal had some environmental nuisances associated such as unpleasant odors and the attraction of flies. The neighbors near site 9 complained about it. Also there was the potential for serious groundwater contamination. We began looking at other sludge treatment and disposal options. In 1995, we started pilot composting trials in order to determine optimal operating conditions in a large scale composting operation. Problems with site 9N previous disposal system
  12. 12. 12
  13. 13. Composting Rules C:N from 25:1 to 40:1 Moisture ~ 40 to 65% Oxygen > 5 ppm Temperature 55 - 65 o C for a total of 5 days
  14. 14. Why do it? Dry matter/volume reduction ~ 50% Cheaper transportation Land apply at farmer’s convenience Reduced odor Reduces fly and disease problems Can help manage storage capacity
  15. 15. Aerobic microorganisms (Composting process) Raw undigested sludge Treated sludge AerationMoisture Heat Moisture CO2
  16. 16. Bacteria, actinomycetes, fungi How to eat something bigger than you are…..
  17. 17. Respiration Oxygen in – bugs oxidize carbon sources Energy used to build cells CO2 and heat out
  18. 18. 18 First step: Windrow formation Equipment used are trucks and loaders.
  19. 19. Second step: Make windrow more homogeneous and adjust moisture content to optimal level (around 50 – 60 %) Equipment used: Loader and composter 19
  20. 20. 20
  21. 21. Third step : Aeration with objective to maintain oxygen concentration in windrows above 5%. 21
  22. 22. Forth step : turning windrows to aerate and to keep temperatures in the effective range of 55 – 65 . 22
  23. 23. Fifth step: maturation 23 Curing or maturing is a critical phase that follows thermophilic composting. During this period, which may last for several months, actinomycetes and fungi slowly break down the remaining digestible material.
  24. 24. Raw Sludge Characteristics  Moisture 70% - 80%  Total solids 20% – 30%  Volatile solids 65% – 70 %  PH 7 – 7.5 24
  25. 25. Sludge characteristics after composting  Moisture 10 – 20%  Total solids 80 – 90%  Volatile solids 35 – 45 %  PH 7 – 7.5  Nitrogen 1.2 – 1.8  Phosphors .8% - 0.9%  Potassium .3 – .4 % 25
  26. 26. Final Heavy Metals Concentrations in Sludge Compost Patch 5 ppm Patch 4 ppm Patch 3 ppm Patch 2 ppm Patch 1 ppm Safe limits ppm Eleme nt Element 635 759 721 840 774.2 2800 Zn ‫زنك‬ 288 462 427 491 208.7 1500 Cu ‫نحاس‬ 27 110 140 136 22.6 420 Ni ‫نيكل‬ 2.6 9.7 8.5 10.5 1.0 39 Cd ‫كادميوم‬ 66 171 163 182 265.7 300 Pb ‫رصاص‬ 1.4 - - - 5.75 17 Hg ‫زئبق‬ 153 105 105 104 20.4 1200 Cr ‫كروم‬ 1 - - - - 18 Mo ‫موليبدنم‬ 2.5 - - - - 36 Se ‫سيلينيوم‬ 7.3 - - - 0.8 41 As ‫زرنيخ‬ 26
  27. 27. 27 Final Sludge Compost Quality Value Indicator ‫التحليل‬ 5.2 E.C. dsm-1 ‫الكهربي‬ ‫التىصيل‬ 7.1 pH ‫والقلىيت‬ ‫الحمىضت‬ 39.4 O.M % ‫العضىيت‬ ‫المادة‬ 1.2 N % ‫الكلي‬ ‫النيتروجين‬ 221 N, ppm ‫المتاح‬ ‫النيتروجين‬ 0.41 P% ‫الكلي‬ ‫الفىسفىر‬ 140 P, ppm ‫المتاح‬ ‫الفىسفىر‬ 0.93 K % ‫البىتاسيىم‬ 166 Mn, ppm ‫المنجنيس‬ 161 Fe, ppm ‫الحديد‬ 751 Zn, ppm ‫زنك‬
  28. 28. The microbiological characteristics of the final compost product  1- Free of pathogenic bacteria, such as: - Fecal coliform, Salmonella .  2- Free of Eggs of Ascaris ova  3- Free from weed seeds.  4- Free of Nematodes. 28
  29. 29. At site 9 we have consistently composted and achieved a high compost quality in a safe and cost effective manner
  30. 30. 10215.5 12062.64 7460 11241 54531.65 116259 25351.25 16596.5 30885.5 65917.5 26100 26006.25 21278.25 8691.5 0 20000 40000 60000 80000 100000 120000 (Cubicmeters) 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 (Years) The quantity of sludge compost sold at site 9N
  31. 31. Application of sludge compost on corn trials No compost added After compost added at the rate of 15 ton per feddan
  32. 32. Application of sludge compost on cotton trials No compost: Output is 5 tons per feddan With compost: Output is 13 tons per Fadden
  33. 33. Forest 9 N tells about the effectiveness of the sludge compost to gradually turn stony limestone into a fertile soil

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