Partial anammox achieved in full scale biofilm process for typical domestic wastewater treatment

The slow initiation of anammox for treating typical domestic wastewater and the relatively high footprint of wastewater treatment infrastructures are major concerns for practical wastewater treatment systems.Herein,a 300 m^(3)/d hybrid biofilm reactor(HBR)process was developed and operated with a short hydraulic retention time(HRT)of 8 h.The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process.The percentage abundance of Candidatus Brocadia in the total bacterial community of the anoxic zone increased from 0 at Day 1 to 0.33%at Day 130 and then to 2.89%at Day 213.Based upon the activity of anammox bacteria,the removal of ammonia nitrogen(NH_(4)^(+)-N)in the anoxic zone was approximately 15%.This showed that the nitrogen transformation pathway was enhanced in the HBR system through partial anammox process in the anoxic zone.The final effluent contained 12 mg/L chemical oxygen demand(COD),0.662 mg/L NH_(4)^(+)-N,7.2 mg/L total nitrogen(TN),and 6 mg/L SS,indicating the effectiveness of the HBR process for treating real domestic wastewater.

Flow characteristic and wastewater treatment performance of a pilot-scale airlift oxidation ditch

A pilot-scale airlift oxidation ditch using bubble diffuser and baffle as aerator was operated in a wastewater treatment plant(WWTP)to investigate its flow characteristic and wastewater treatment performance.Compared with the conventional oxidation ditch process,effective depth and oxygen utilization efficiency of this new process was improved by underwater aeration.Furthermore,it had a reversed velocity distribution,which decreased from the bottom to the top on vertical section.Velocity measurement showed that a velocity over 0.2 m/s at the bottom was sufficient to prevent sludge settlement during long term operation.Application of these concepts would save land area and energy consumption by about 25%–50%and 55%,respectively.In this new system,organic biodegradation and nitrification could be well achieved.Denitrification could occur steadily in the straight part by adjusting the airflow rate.An average TN removal rate of 63%was achieved with dissolved oxygen(DO)concentrations between 0.6 mg/L and 1.5 mg/L.The main pollutants in the effluent could meet the strictest discharge standard(COD<50 mg/L,NH4_(+)^(–)N<5 mg/L,and TN<15 mg/L)in China now.