Improvement of nitrogen removal at WWTP Zuerich Werdhoeelzli after connection of WWTP Zuerich-Glatt

摘要

Optimisation of nitrifying activated sludge plants towards nutrient removal (denitrification and enhanced P-removal) leads to a substantial reduction of operating costs and improves effluent and operating conditions. At WWTP Zuerich-Werdhoeelzli, initially designed for nitrification only, an anoxic zone of 28% of total activated sludge volume was installed and allowed 60% nitrogen elimination besides several other optimisations. In 2001 the operation of WWTP Zuerich-Glatt was stopped and the wastewater was connected to WWTP Werdhoelzli. To improve nitrogen removal, WWTP Werdhoelzli co-financed two research projects; one for separate digester supernatant treatment with the anammox process operating two SBRs in series and the other applying NH_4 sensors for aeration control in order to decrease energy consumption and raise effluent quality. The results of both projects and the consequences for WWTP Werdhoelzli are discussed in this paper.