Academic Study on the Technology Based on Sludge Concentration Subarea

Sludge concentration subarea(A area and B area) is realized by mesh filter unit,solving the higher sludge concentration process problem of MBR system under zero excess sludge discharge conditions.Mass balance of the system is processed,and variety disciplinarians of VSS of A area and B area are analyzed.The results show that XA decreases while HRTA increases.XB decreases while R increases,and ascends as VSS(XA,B) of mesh effluent increases.When XB is a fixed value,XA,B increases as R does and XA decreases slowly while R increases,which theoretically proves the feasibility of the technique.

Start-up of PN-anammox system under low inoculation quantity and its restoration after low-loading rate shock

Partial nitritation(PN)-anaerobic ammonium oxidation(anammox)is a promising pathway for the biological treatment of wastewater.However,the destruction of the system caused by excessive accumulation of nitrate in long-term operation remains a challenge.In this study,PNanammox was initialized with low inoculation quantity in an air-lift reactor.The nitrogen removal rate of 0.71 kgN/(m^(3)·d)was obtained,which was far higher than the seed sludge(0.3 kgN/(m^(3)·d)).Thereafter,excess nitrate build-up was observed under low-loading conditions,and recovery strategies for the PN-anammox system were investigated.Experimental results suggest that increasing the nitrogen loading rate as well as the concentration of free ammonium failed to effectively suppress the nitrite oxidation bacteria(NOB)after the PN-anammox system was disrupted.Afterwards,effluent back-flow was added into the reactor to control the up-flow velocity.As a result,an aggressive discharge of sludge that promoted the synergetic growth of functional bacteria was achieved,leading to the successful restoration of the PN-anammox system.The partial nitritation and anammox activity were in balance,and an increase in nitrogen removal rate up to 1.07 kgN/(m^(3)·d)was obtained with a nitrogen removal efficiency of 82.4%after recovery.Besides,the proportion of granular sludge(over 200 mm)increased from 33.67%to 82.82%.Ammonium oxidation bacteria(AOB)along with anammox bacteria were enriched in the granular sludge during the recovery period,which was crucial for the recovery and stable operation of the PN-anammox system.