PROCESSALTERNATIV FÖR KVÄVEREDUKTION – SAMMANFATTANDE RESULTAT AV 2-ÅRIG FÖRSÖKSDRIFT / Process Alternatives for Nitrogen Removal – Concluding Results of 2-Year’s Trial Operation
Trial operation with biological nitrogen removal was started up on July 1, 1989, in an extended activated sludge line at the sewage treatment plant Västra Stranden in Halmstad with financial support of ”New Technics” by Swedish Environmental Protection Agency. The possibilities to increase the nitrogen removal as well as the phosphorus removal have been investigated but the main issue has been the nitrogen removal in order not to exceed 8 mg/l alternatively 12 mg/l total nitrogen in the effluent from the trial line. The results of extensive investigations have shown that the maximum flow to the trial line shall be limited to 800 m3/h (about 1.25 m3/m2*h for vertical settling and about 0.75 m3/m2* h for horizontal settling) compared to the maximum flow up to about 1,500 m3/h during the trial operation. Trial operation with polymer dosing in order to increase the critical flow has been performed with two polymers so far, which have given good results in laboratory tests but not in full-scale operation. “Complete abstract not presented.”