Study On Treatment Of Anaerobically Digested Effluent Of Swine Wastewater By Sharon-Anammox Process Based On Biological Sand Filter

Although anaerobic digestion has been widely used in the treatment of swine wastewater, its digestedeffluent remains a type of organic wastewater characterized by low COD/N ratio. While conventionaldenitrification process is used for the treatment of anaerobically digested effluent of swine wastewater,there exist the problems of low NH₄⁺-N removal efficiency, high energy consumption and unstableoperation. Thus, it is imperative to develop new-type of denitrification process. In view of the problems,the treatment of anaerobically digested effluent of swine wastewater by Sharon-Anammox process wasstudied with the support of the funds earmarked for Modern Agro-industry Technology ResearchSystem in China (CARS-36). The main conclusions are as follows:(1) After31days' operation, partial nitritation biological sand filter has been successfully started bygradually improving influent NH₄⁺-N concentration of anaerobically digested effluent of swinewastewater. The nitritation ratio (NO₂^–-N/NO_x^–-N) of the biological sand filter was81.0%and effluentNO₂^–-N/NH₄⁺-N ratio was0.82, effectively matching the subsequent Anammox process.(2) Effective NO₂^–-N accumulation could not be achieved by low or high influent NH₄⁺-N loading,thus failing to satisfy the influent requirements for the subsequent Anammox process. Sharon effluentwith0.74of the NO₂^–-N/NH₄⁺-N ratio was obtained when influent NH₄⁺-N loading was57.4g·m^-3·d^-1,relatively matching the influent for the subsequent Anammox process.(3) Sand layer depth affected the transformation of NH₄⁺-N. DNRA and denitrification were proneto taking place in the anoxic environment created by the increasing sand layer depth, which led to theincrease of effluent NH₄⁺-N concentration and the decrease of TIN concentration with the sand layerdepth increasing. Sharon effluent with1.27of the NO₂^–-N/NH₄⁺-N ratio was obtained when sand layerdepth was32cm, well matching the influent for the subsequent Anammox process.(4) Temperature affected the transformation of NH₄⁺-N. Effect of ammonia volatilization increasedwith the temperature increasing. Effective NO₂^–-N accumulation could not be achieved when thetemperature was12°C and35°C. Sharon effluent with0.97of the NO₂^–-N/NH₄⁺-N ratio was obtainedwhen temperature was25°C, relatively matching the influent for the subsequent Anammox process.(5) After270days' cultivation, both suspended and attached Anammox reactors have beensuccessfully started using nitrifying activated sludge as seed sludge. The sludge with Anammox activityhas ultimately been formed after experiencing the adaption phase, the lag phase, the increasing phaseand the stationary phase. Removal efficiencies of NH₄⁺-N, NO₂^–-N and TIN by suspended and attachedreactors showed that suspended cultivation was appropriate for cultivating Anammox sludge.(6) With the treatment of anaerobically digested effluent of swine wastewater by Sharon-Anammoxprocess, effluent NH+14-N concentration was13.8mg·L^-1while influent NH₄⁺-N concentration was258.2mg·L^-1. The combined process has a stable nitrogen removal, with41.3%of the TIN removal efficiency.