Research Of Biological Treatment Of The High Salinity Wastewater

As the growing of the seawater utilization and industrial wastewater emissions, highsalinity wastewater disposal attracted more and more attention. This wastewater contains highsalinity and serious pollution. It must be treated for discharging. The wastewater biologicaltreatment technology still was the preferred method because of the high costs of the physicaland chemical treatment technology. But the biological treatment technology met seriouschallenge because of high salinity. Domestic and foreign scholars carried on experiment ofhigh salinity wastewater using biological treatment technology by artificial enhanced method,and obtained some results.This paper studied on the treatment of high salinity wastewater from two aspects. Firstly,the activated sludge was acclimated in sequencing batch biofilm reactor （SBBR）. Degradationof organic and variation of NH₄⁺-N removal were studied at different salinity. It was alsostudied that the impact on the system of organic load. Secondly, the halophilic bacteriaadapted to high salinity were isolated from the substrate sludge and inoculated into thesequencing batch reactor （SBR）. The growth characteristics of halophilic bacteria and thedegradation of organic and the variation of NH₄⁺-N were studied. It was also studied theimpact on the systems of the organic load and salinity load.The high salinity wastewater was treated in SBBR. The results showed that, during theacclimation period of the salt concentration at0%～2%, the effluent COD and NH₄⁺-Nconcentration increased initially, and gradually decreased later. The removal rates were above94%and71%respectively. The sludge volume index （SVI） decreased gradually with theincrease of salinity. SVI decreased quickly in the low salinity stage, and stabilized at25mL/glater. The salinity increased from0%to2%, in the reaction cycle of every stage, the CODremoval rate of the effluent stabilized at93%～97%, and the NH₄⁺-N removal rate reducedfrom93%to72%. When the salinity stabilized at2%, variation of the influent organic loadhad little effect on COD removal efficiency, and the effluent COD removal efficiency wasabove92%. It was indicated that the system had a strong resistance of shock organic load. The halophilic bacteria were isolated from the substrate sludge of Dalian Lvshun Salt Fieldin China, carried out enrichment acclimation and inoculated into SBR. When the system wasstability, the activated sludge average concentration reached600mg/L. The removalefficiency of COD was more than95%, NH₄⁺-N removal efficiency was53%～64%. Thespecific oxygen uptake rate （SOUR） was measured, and the results showed that theendogenous and exogenous respiration of oxygen uptake rate were reached10.36mgO₂/gVSS·h and29.09mgO₂/gVSS·h respectively. It was indicated that the acclimationsludge had high activity. The concentration of COD, NH₄⁺-N, TP was decreased obviouslywithin1h in a reaction cycle. With the reaction time extended, its removal efficiency changedlittle, and the final effluent COD, NH₄⁺-N, TP removal rates were95%,61%,55%respectively. Variation of the influent organic load and salinity load had little effect on CODremoval efficiency. But there was significant variation of NH₄⁺-N removal efficiency whenthe salinity were2%,3.5%,5%, and the NH₄⁺-N removal efficiency were41%,61%,31%respectively. It was indicated that variation of salinity had greatly effect on the removal ofNH₄⁺-N.