‘After implementing the vacuum degassing system with simultaneous phosphate precipitation: ELOVAC®-P, we no longer have problems with struvite scaling. With ELOVAC®-P we not only avoid operational problems, but also save on disposal and polymer costs.’
ELOVAC® is a technology for vacuum degassing of digested sludge with an option for integrated phosphate precipitation - compact and ready to connect. This technology is particularly beneficial for all anaerobic digestion plants looking to reduce their environmental footprint. With the optional phosphate precipitation, ELOVAC® improves dewatering, saves polymer costs, reduces phosphate backwater and helps avoid struvite deposits.
After the digester, the digested sludge still contains methane in dissolved form and in the form of micro gas bubbles. This methane, which is harmful to the enviroment, is released into the atmosphere during the sludge storage and dewatering of the digested sludge. ELOVAC®-P captures this gas which can then be used as biogas. This significantly improves the carbon footprint of the wastewater treatment plant.
ELOVAC® is supplied as a ready-to-connect, compact, skid-mounted system. This enables placement in a building or a container that can be set up flexibly on-site.
Dissolved phosphate improves the water binding capacity of EPS and proteins (Kopp, 2013*), meaning there is an inverse relationship between the phosphate concentration in the sewage sludge and the dry matter content after dewatering. The higher the phosphate concentration, the lower the dry solids content. Therefore, precipitation of the phosphates leads to improved dewatering and reduced polymer demand. At the Lingen sewage treatment plant, for example, ELOVAC®-P has increased the dewatering result (DS(A) value) by more than 5 % points, saving approximately 20 % of disposalcosts.
Vacuum degassing removes CO2 from the digested sludge in addition to methane, thereby increasing the pH value. With the addition of magnesium chloride this creates the perfect environment for controlled phosphate precipitation. Microcrystals are formed which remain in the sludge and do not adhere to pipe walls, tanks and the dewatering aggregates. The pH value is only slightly increased. At the same time, the phosphate concentration drops significantly - and with it the risk of uncontrolled struvite deposits after ELOVAC®-P.
Struvite is a long-term fertiliser with very high plant availability. When ELOVAC®-P is used, the struvite crystals remain in the dewatered sludge. This improves the quality of the dewatered sludge as an agricultural fertiliser.
The functional principle of ELOVAC®
Footprint: Example of an ELOVAC®-P 20 unit
ELOVAC®-P - scalable fit for your requirements
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Quote from Mr. Hüer, Management, treatment works of Lingen (EMS):