innovation & technology Water Digelis Turbo Boosting biogas production for greater energy recovery

Transcription

1 innovation & technology Digelis Turbo Boosting biogas production for greater energy recovery Water

2 Enhancing anaerobic digestion processes through thermal hydrolysis Digelis Turbo integrates a sludge thermal hydrolysis pre-treatment step to improve the destruction of volatile matter in sludge during the anaerobic digestion process. This improvement helps to enhance anaerobic digestion, boost the production of biogas and reduce the quantity of sludge. Biogas can be converted into heat and electricity to power on-site facilities or treated further to produce green gas or biofuel. Along with its operational advantages, the Digelis Turbo process requires a smaller footprint than conventional anaerobic digesters. The benefits Performance and operation The production of biogas from biological sludge increases by up to 50% The volume of sludge to be disposed of is remarkably reduced due to the enhanced destruction of volatile matter during anaerobic digestion and the improved dryness of dewatered sludge The collected sludge is sanitised and highly stabilised The operating cycles are fully automated Cost savings The costs of sludge disposal are reduced by up to 50% compared to a treatment line without digestion By reducing the sludge volume, savings on the augmentation of downstream sludge treatment steps can be achieved The Digelis Turbo process can help double the capacity of existing digesters The boosted biogas production increases the generation of electricity and/or heat, moving the plant towards energy selfsufficiency and thus reducing operating costs

3 Stage 1 Understanding the Digelis Turbo process Digelis Turbo comprises two processes including thermal hydrolysis pre-treatment and anaerobic digestion. The thermal pre-treatment hydrolyses sludge, which accelerates the destruction of volatile matter in the anaerobic digestion process. Thickened sludge is first homogenised and heated to a temperature close to 100 C in a reactor called the Pulper. The sludge is then hydrolysed under high pressure and high temperature in the Reactor. The sanitised sludge is then sent to a pressure reducing reactor called the Flash Tank where a drop in pressure causes the destruction of the bacteria cells. Thermal hydrolysis breaks down the cell structure of the bacteria present in the sludge. The sludge coming out of the thermal hydrolysis phase is easier to digest which helps to boost the following digestion process. The hydrolysed sludge is then cooled by thermal exchange. The gas produced during stage 1 is sent to the downstream digester. Thermal hydrolysis Raw sludge 16-17% dry matter Living bacteria Dead bacteria Inert suspended solids (SS) Exopolymers Hydrolysed sludge to digester 8-12% MS Hydrolysed SS Cell content Cell Wall Inert SS Exopolymers Stage 2 The sludge and gas produced by the thermal hydrolysis process are transferred to a conventional anaerobic digestion process where the volatile matter is converted into biogas. The biogas can be used to generate steam through a boiler to operate the Reactor in stage 1. Additionally, it can be used to produce electricity to power on-site facilities or further treated to create biofuel or green gas.

4 References Santiago, Chile Burgos, Spain Ourense, Spain 2,500,000 PE* 1,000,000 PE* 300,000 PE* *PE: population equivalent SUEZ s wastewater treatment plant in Santiago, Chile provides wastewater service to over 2.5 million people

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