The project is both a methane emissions reduction and energy production project.Methane produced in Kubratovo wastewater treatment plant is captured in common methanetanks serving as a buffer and then supplied to the newly installed CHP gas engines forelectricity and heat production, which in turn will substitute both the plant's electricity purchasesfrom the grid and diesel fuel usage. Excess electricity is supplied to the grid.The main purpose of the project is to transform the existing low tech sludge treatment processat Kubratovo into a modern advanced treatment process matching the best sludge treatmentpractice available in Western Europe. This transformation has a major effect on the environmentthrough dramatically reducing the existing methane gas emissions at the plant while alsoreducing the volume of sludge (to as much as 50%) that needs to be transported, hencereducing GHG emissions from transportation as well (not included in GHG abatementcalculations).The overall objective of the project is to provide an environmentally friendly sludge treatmentprocess reducing methane and carbon dioxide emissions that – under a business-as-usualscenario – would have continued.Other objectives are:• replace the traditional sludge drying beds and landfill options with mesophilic digestion ofall primary and secondary sludge followed by mechanical dewatering in order to reduceGHG emissions;• effectively mitigate odour problems from the existing treatment of sludge and sludgeliquors through introduction of digestion;• production of fertiliser by mechanical dewatering of the digested stabilised sludge;• production of electricity from utilisation of the biogas in CHP gas engines therebyreducing GHG emissions from electricity production by the grid.The project delivers the following key results:• all primary and secondary sludge thickened and digested as per EU recommendationsand guidelines;• all biogas produced within the digestion process used for power and heat generation viaCHP gas engines thus reducing on-site electricity purchases from the national grid;reduction in on-site fossil fuel usage as all site-heating requirements will be met by theCHP gas engines;• all sludge is stabilised and pathogen free.Long term strategic reductions of GHG emissions include:• reduction in open release of CH4 from open anaerobic sludge tanks and drying beds;• reduction in open release of CH4 from landfill disposal site;• reduction in CO2 emissions due to replacement of electricity production from fossil fuels;• reduction in CO2 emissions due to replacement of heat generation from fossil fuels.The project had been implemented in two stages:- Erection of a new digester system consisting of 4 digesters, 7,000 m3 each, designed,supplied and erected by PASSAVANT ROEDIGER Anlagenbau.For destroying of the excess methane in case of emergency a flaring system have beenimplemented, consisting of 2 x DN150 flares, type ZA1-F2-0/N0 designed andmanufactured by HEGWEIN GmbH, Germany.- Erection of 3 new co-generation sets GE JMS 320 GS-B.LC with 1,063 kW electriccapacity each and 1,088 kW thermal capacity, for generation of electric and thermalenergy by combusting biogas from digesters.The digesters were commissioned at the end of 2006 and started operation on 01 January 2007but due to some technical problems in the adjustment of the biological process the generation ofbiogas was interrupted in the end of June 2007 and resumed on 01 May 2008, so the firstindustrial quantities of biogas were registered in May, 2008.The CHP was commissioned and started generating electricity and thermal energy for plant'sneeds in November, 2009.