pelletizing of faecal sludge. processing of faecal … of faecal sludge. processing of faecal sludge...

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Pelletizing of faecal sludge. Processing of faecal sludge into fuel pellets. Faecal sludge management Worldwide, sanitation needs of 2.7 billion people are met by onsite sanitation technologies such as septic tanks and pit latrines. These technologies can provide adequate sanitation if the produced faecal sludge is adequately managed. However, currently large amounts of faecal sludge are discharged untreated directly into the environment, with negative impacts on public and environmental health (see www.sandec.ch/fsm_book). Faecal sludge resource recovery Faecal sludge is a nutrient and energy resource. Faecal sludge treatment can produce marketable endproducts such as biogas, solid fuels, animal fodder or soil conditioner. Depending on the local market demand, these treatment endproducts can help to cover faecal treatment costs. For example, in Kampala faecal sludge as a solid fuel for industries can provide higher revenues compared to the conventional use as soil conditioner in agriculture. Faecal sludge fuel pellets Pellets were produced from dewatered faecal sludge from drying beds at the Lubigi Wastewater and Faecal Sludge Treatment Plant in Kampala, Uganda, operated by the National Water & Sewerage Corporation (NWSC). Pellets were produced without the addition of a binder at a moisture content of 40-55% at a rate of 20-35 kg per hour and pelletizing units. Co-management of biowastes Faecal sludge was also co-pelletized with other biowastes such as sawdust, coffee husks, banana peels and brewery waste. Co- processing with these biowastes increases the fuel quality (e.g. ash content, calorific value) and quantity. Such pellets produced from different wastes are of high and consistent quality and can be sold as fuel on the industrial market. Drying of faecal sludge pellets Advantageously, faecal sludge pellets have faster drying rates then sludge treated with drying beds. In Kampala, faecal sludge pellets dried from 50% to 90% in one week. Whereas on drying beds, this requires several weeks to months. Pellet drying can be enhanced by active ventilated greenhouses or silo dryer. This means that the footprint of treatment plants could be reduced, or the treatment capacity increased, which is very important in urban areas with limited space. Energy recovery The Bioburn pelletizer only consumes 1-5% of the energy that is contained in faecal sludge pellets as electricity. In Kampala, brick and cement companies are interested in using faecal sludge as a fuel. In addition, pellets could be a good feedstock for gasification technologies. Challenges with energy recovery of faecal sludge in Kampala include the high ash content (>35%).

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Page 1: Pelletizing of faecal sludge. Processing of faecal … of faecal sludge. Processing of faecal sludge into fuel pellets. Faecal sludge management Worldwide, sanitation needs of 2.7

Pelletizingoffaecalsludge.Processingoffaecalsludgeintofuelpellets. FaecalsludgemanagementWorldwide, sanitation needs of 2.7 billion peopleare met by onsite sanitation technologies such asseptictanksandpitlatrines.Thesetechnologiescanprovideadequate sanitation if theproduced faecalsludge is adequatelymanaged. However, currentlylarge amounts of faecal sludge are dischargeduntreated directly into the environment, withnegative impacts on public and environmentalhealth(seewww.sandec.ch/fsm_book).FaecalsludgeresourcerecoveryFaecal sludge is a nutrient and energy resource.Faecal sludge treatment can produce marketableendproducts such as biogas, solid fuels, animalfodder or soil conditioner. Depending on the localmarket demand, these treatment endproducts canhelp to cover faecal treatment costs. For example,in Kampala faecal sludge as a solid fuel forindustriescanprovidehigherrevenuescomparedtothe conventional use as soil conditioner inagriculture.FaecalsludgefuelpelletsPellets were produced from dewatered faecalsludge from drying beds at the LubigiWastewaterand Faecal Sludge Treatment Plant in Kampala,Uganda, operated by the National Water &Sewerage Corporation (NWSC). Pellets wereproduced without the addition of a binder at amoisture content of 40-55% at a rate of 20-35 kgperhourandpelletizingunits.

Co-managementofbiowastesFaecal sludge was also co-pelletized withother biowastes such as sawdust, coffeehusks, banana peels and brewerywaste. Co-processingwiththesebiowastesincreasesthefuel quality (e.g. ash content, calorific value)and quantity. Such pellets produced fromdifferentwastes are of high and consistentquality and can be sold as fuel on theindustrialmarket.

DryingoffaecalsludgepelletsAdvantageously, faecal sludge pellets havefaster drying rates then sludge treated withdryingbeds. InKampala,faecalsludgepelletsdriedfrom50%to90%inoneweek.Whereasondryingbeds,thisrequiresseveralweekstomonths. Pellet drying can be enhanced byactive ventilated greenhouses or silo dryer.This means that the footprint of treatmentplants could be reduced, or the treatmentcapacityincreased,whichisveryimportantinurbanareaswithlimitedspace.EnergyrecoveryTheBioburnpelletizeronlyconsumes1-5%ofthe energy that is contained in faecal sludgepellets as electricity. In Kampala, brick andcement companies are interested in usingfaecal sludge as a fuel. In addition, pelletscould be a good feedstock for gasificationtechnologies.Challengeswithenergyrecoveryof faecal sludge in Kampala include the highashcontent(>35%).

Page 2: Pelletizing of faecal sludge. Processing of faecal … of faecal sludge. Processing of faecal sludge into fuel pellets. Faecal sludge management Worldwide, sanitation needs of 2.7

SludgetoEnergyEnterpriseinKampala(SEEK)Project

The SEEK Project is (2014-2016) an international multi-disciplinary research product implemented inKampala, Uganda, and funded by the Symphasis Foundation and REPIC platform (Promotion ofRenewableEnergyandEnergyEfficiency inDevelopingandTransitionCountries).ProjectpartnersareBioburn, the Swiss Federal Institute of Aquatic Science (Eawag), Makerere University, Centre forResearchinEnergyandEnergyConservation(CREEC)andtheNationalWater&SewerageCorporation.

Projectpartners

Eawagwww.sandec.ch

BioburnAGwww.bioburn.ch

NWSCwww.nwsc.co.ug

MakerereUniversitywww.cedat.mak.ac.ug

CREECwww.creec.or.ug

Financialpartners

REPICwww.repic.ch

Symphasiswww.symphasis.ch