| Now the viewpoint whether the effects of salinity on biological treatment systemwas good or not and the removal effects of organics and ammonia in the high salinityenvironment were not consistent in the biological treatment of high salinity wastewater.The reports about the kinetics research on the degradation of organics and ammonia in thehigh salinity wastewater at normal temperature and the effects of double adversefactors-low temperature and high salinity on the removal of organics and ammonia werelacking. What's more, the research on the effects of low temperature on activated sludgesystem and the analysis in view of biology in the high salinity wastewater were rare. As tothese questions, in this paper the effects of different wastewater salinity on organics andammonia removal as well as kinetics analysis were mainly studied by Sequencing BatchReactor (SBR) process. Besides the effects of low temperature on activated sludge systemand two styles of temperature drop-low temperature drop and sharp-temperature drop onorganics and ammonia removal were studied within 6℃～20℃. As to these contents, theanalysis in view of biology was illustrated. These researches were promotive to thebiological treatment of high saline wastewater.Experimental results showed that the efficiency of organics and ammonia removaldecreased with the salinity increasing at normal temperature (20℃) when wastewatersalinity was over 10.5g/L. The experimental parameters were: pH:8.0;dissolved oxygen:2.0～3.0mg/L; mixed liquid suspended solid concentration: 3000mg/L; At the influentCOD concentration of 360mg/L, when the seawater proportion increased from 30％(Thesalinity was 10.5g/L) to 50％(The salinity was 19.5g/L), COD removal efficiencydecreased from 87％to 82％. The effect of salinity on COD removal efficiency was notobvious; When the seawater proportion was over 50％and reached 70％(The salinity was24.5g/L), the effect of salinity on COD removal efficiency was obvious and decreased to68％. At the influent ammonia concentration of 62mg/L, when the seawater proportionwas 30％, 50％and 70％, ammonia removal efficiency was 91％, 86％and 80％respectively. The effect of salinity was not remarkable. When the seawater proportion wasover 70％and reached 100％(The salinity was 35g/L), ammonia removal efficiencydecreased remarkably to 67％. When seawater was above 30％, nitrite was accumulatedduring biological nitrifying process and shortcut nitrification-denitrification was achieved.According to the curves of COD and ammonia degradation during a circle, the value ofthe degradation rate constant of organics and ammonia at different proportion of seawaterwere worked out through Thomas illustration. The value of the COD degradation rate constant at 30％, 50％and 70％seawater was 0.7886h-1, 0.7504h-1 and 0.7273h-1respectively; The value of the ammonia degradation rate constant at 30％, 50％, 70％and100％seawater was 0.2717h-1, 0.139h-1, 0.118h-1 and 0.1079h-1 respectively. These datashowed that the degradation rate constant dropped with the seawater salinity increasing.Besides, denitrification rate reduced due to the increase of salinity in the wastewater.When seawater proportion was 50％, the removal efficiency of organics andammonia reduced with the temperature dropping, within 6～15℃. Experiments showedthat the activated sludge system got worse effect when temperature dropped fast. Theexperimental parameters were: pH: 8.0;dissolved oxygen: 2.0～3.0mg/L;mixed liquidsuspended solid concentration: 3000rag/L; At the influent COD concentration of360mg/L, during the process of low temperature drop the COD removal efficiency of 15℃,10℃and 6℃was 69.84％, 56.24％and 46.54％respectively. At the influent ammoniaconcentration of 39mg/L, the ammonia efficiency of 15℃, 10℃and 6℃was 77％, 46％and 28％respectively. At the same experimental parameters, during the process of sharptemperature drop the COD removal efficiency of 15℃, 10℃and 6℃was 69％, 37％and26％respectively. The ammonia efficiency of 15℃, 10℃and 6℃was 73％, 35％and19％respectively. Compared to organics removal efficiency, low temperature had worseeffect on ammonia. In the view of biology, the activity of mesophilic microorganismreduced with the temperature dropping. When the wastewater temperature was below10℃, the principle force to decompose organics and ammonia in wastewater werecold-adapted microorganism, for the mesophilic microorganism nearly had no ability tometabolize allogenic materials at such low temperature. The adsorption and settlingperformance of activated sludge became worse at low temperature.Nitrifying bacteria in the wastewater containing 50％seawater were affectedadversely by low temperature and high salinity within 6℃～15℃. First of all, nitrate'sgrowth was restrained because of high salinity, thus nitrite was accumulated duringbiological nitrification. At the same time, the activity of nitrosomas was inhibited at lowtemperature. During the process of nitrifying, the rate of ammonia degradation was higherthan that of nitrite growth. The difference was more obvious at the lower temperature.The ammonia degradation rate of 15℃, 10℃and 6℃was 0.0239gNH3—N/gMLSS.d, 0.0174gNH3—N/gMLSS.d and 0.0104gNH3—N/gMLSS.d respectively; Atthe same temperature, the nitrite growth rate of 15℃, 10℃and 6℃was0.0128gNO2—N/gMLSS.d,0.0065gNO2—N/gMLSS.d and 0.00234gNO2—N/gMLSS.drespectively. This showed that ammonia degradation was mainly due to biologicalassimilation at low temperature. Only a small part of ammonia was converted to nitrite.
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