Thanks to the two new facilities, more biogas will be extracted from the sludge and the amount of residual product at the end of the process will be drastically reduced. The purification of the water extract, which is released during the dewatering of the sludge, will be significantly improved, Sofia Water reports. This will also facilitate the next stage in the purification of the water before its return to nature.
The first facility introduces thermal hydrolysis technology. In the standard sludge treatment process, it undergoes thickening before entering the methane tanks where biogas is extracted from it. With the newly built power, an intermediate step is introduced before the methane tanks, in which, under high temperature and pressure, the microorganisms in the sediments are degraded.
This leads to several benefits. First of all, the volume of the sediment that remains at the end of the purification process, practically a residual product, decreases. If until now the ratio of sludge converted into biogas and residual sludge was 40% to 60%, the new technology optimizes it to 60% to 40% in favor of the sludge converted to biogas. In addition, the need for a 6-month settling of the sludge will be eliminated, as it will be suitable for agricultural use immediately after the processing and stabilization process. All this will also lead to optimization in its utilization.
The entire process will be energy autonomous, as it is provided by the green energy generated by the increased amount of biogas extracted from the sludge. Thus, the energy balance of the station and the ambition of Sofia Water to be completely energy neutral by 2025 are preserved.
The second new installation treats the liquid that is released in the sludge dewatering process. The liquid separated here has so far been fed directly into the biobasins for the next stage of purification. However, the nitrogen content in the liquid entering the biobasins was high. According to the latest environmental requirements of the EU, nitrogen in the treated wastewater must be reduced, which the newly built anammox plant will help to achieve. Thanks to it, the amount of nitrogen in the water from dewatered sludge should drop by 90%, and thus the purified water discharged into nature will fully meet the latest European requirements.
With the implementation of the two new technologies, the Sofia Waterworks operator is once again a pioneer in the technological development of the sector. The installations are a novelty not only for Bulgaria, but they are also rarely found in the network of the concessionaire of Sofia Water – Veolia, which operates in 58 countries around the world.
The construction of a facility for thermal hydrolysis and anammox installation at the “Kubratovo” WWTP is being implemented according to a project of the Metropolitan Municipality under the OP “Environment”. It is part of the CO sludge management strategy developed in partnership with Sofia Water, part of Veolia.
Tags: facilities optimize waste treatment ..
