Case Study a – Hamburg WWTP Develop

Case Study a – Hamburg WWTP Development of energy integration and surplus 2010 onwards From 1995 onwards, electricity consumption has been reduced from 100 to less than 79 GWh p.a.; renewable electricity generation increased to more than 80 GWh p.a. A continuous energy surplus of almost 10% has already been achieved since 2010; now exceeding consumption by 15%.  Stage 1: Digesting the sludge on site was a way to decrease the amount; digester gas was then used for heating the digesters. The incineration plant named VERA was put into operation in 1998.  Stage 2: High-tech solution to dry and incinerate the sewage sludge in a combined process with the usage of digester gas for electricity generation.  Stage 3: Energy savings; aeration system changes, plus other projects led to an overall saving of more than 20%.  Stage 4: 2 wind turbines with 8 MW rated power were added; equipped with advanced and multiple safety systems  Stage 5: Co-fermentation of various types of biological wastes and feeding surplus digester gas into the natural gas grid. Due to variable gas qualities, a plant for upgrading the digester gas has been installed. This treatment was chosen because it requires heat as auxiliary energy for regeneration of the amine suspension, which can be covered from the sludge incinerationEnergy balance trend at Hamburg WWTPIncineration energy recovery • Digester gas is combusted in a gas turbine of 5 MW & gas engine of 2 MW rated power. Exhaust waste heat is then again used for the steam turbine in the sludge incineration process. • After mechanical dewatering and thermal drying the sludge is incinerated in fluidized bed incinerators. The heat from incineration is used to produce steam, driving a two-stage steam turbine for electricity production. • Steam is withdrawn from a tapping behind the first stage to provide the high heat demand of the thermal sludge drying plant on a high temperature level. • The residual waste heat of the thermal drying process on a low temperature level is subsequently used to supply the gas digesters, all buildings of the WWTP and -since 2009 - even the neighboring container terminal of the Hamburg seaport.Energy Management Options – Case Study b – Davyhulme UK & Seince Aval, France Typical process diagram for biogas also involving thermal hydrolysis/treatment of sludge Al-Mutla’a WWTP TSE, Sludge, & Energy Options