| It has a long history of producing mustard in Fuling Chongqing. In themanufacturing process of the mustard, there is a lot of mustard wastewater with highsalinity, high nitrogen and organic concentration every year. At the present, there are afew treatment methods of mustard wastewater. But, these methods with thecharacteristics of high investment, high consumption and low efficiency cann’t treatwith mustard wastewater effectively to pollute the Three Gorges Reservoir region’swater environment. SHARON-ANAMMOX process is highly efficient, cost-effectiveand environmentally friendly biotechnology for nitrogen removal, which have attractedmuch attention to the environmentalists and has wide application prospect. Therefore,the combined process of anaerobic treatment in ASBBR, partial nitrification in SBR andANAMMOX in UASB was used to treat with mustard wastewater for removingorganics and nitrogen efficiently. The feasibility of the combined process and theremoval efficiency of organics and nitrogen were investigated in the study.Considering the characteristic of high salinity in mustard wastewater, the followingworks are accomplished:①The anaerobic treatment of mustard wastewater wasachieved in ASBBR by the way of diluting mustard wastewater by stages andinoculating with halophilic bacteria to reduce the concentration of COD dramaticallyand lead to be mainly NH4+-N in nitrogen of effluent, which have ensured the follow-upprocess of ANAMMOX to remove nitrogen successfully;②Started up the nitrificationprocess in SBR by the way of diluting effluent from ASBBR by stages, and then thepartial nitrification process to treat with effluent from ASBBR was achieved in SBR bycontrolling parameters, which have maked the ratio of NO2--N and NH4+-N to be1.0~1.3for suiting ANAMMOX;③Started up and operated the ANAMMOX processin UASB by using synthetic wastewater with salinity, in which the concentration ofnitrogen and the salinity were same with the mustard wastewater. And then, fed witheffluent of SBR to remove nitrogen after treating the synthetic wastewater steadily andefficiently in the UASB. The main research conclusions are as follow:⑴On the conditions of pH=7.0~7.2, temperature at30~32℃, HRT=48h, λ=1/2,the anaerobic treatment of mustard wastewater was achieved in ASBBR by the way ofdiluting mustard wastewater by stages and inoculating with halophilic bacteria afteroperating for86days, by using anaerobic activated sludge as the seed. With the loading rate of2.0Kg COD/(m3·d) and the salinity of9600~10000mg Cl-/L, it could reduce theconcentration of COD from3880~4120mg/L in influent to410~445mg/L in effluentand the average COD removal efficiency was89.7%; the average ratio of NH4+-N andTN in effluent was97.6%to be mainly NH4+-N in nitrogen of effluent.⑵On the conditions of DO=0.2~0.5mg/L, pH=7.9~8.2, temperature at29~30℃,HRT=24h, λ=1/2, the nitrification process to treat with effluent of ASBBR wasachieved in SBR by the way of diluting influent by stages after operating for127days,by using aerobic activated sludge as the seed. With the nitrogen loading rate of0.204Kg NH4+-N/(m3·d) and the salinity of9600~10000mg Cl-/L, it could reduce theconcentration of NH4+-N from190~220mg/L in influent to≤1mg/L in effluent and theconcentration of NO2--N was≥180mg/L,which could make the average NH4+-Nremoval efficiency to be about100%, nitrite accumulation rate to be above90%andnitrogen loss to be2~5%.⑶The effect of nitrification during typical cycle indicated that the activity ofAOB wasn’t inhibited by the salinity of9800mg Cl-/L and operation of the nitrificationprocess was stable and efficient on the salinity of9800mg Cl-/L; The Variation of DOand pH during typical cycle indicated that DO and pH could show the end ofnitrification.⑷For the concentration of NH4+-N in influent, the partial nitrification process tosuit ANAMMOX could be achieved by controlling pH in SBR, DO and HRT. In thestudy, under the concentration of NH4+-N was204mg/L, adding KHCO3byHCO3-/NH4+=1(pH=7.7~7.9), the effluent of partial nitrification process was achievedby controlling DO=0.42mg/L and HRT=24h, in which the ratio of NO2--N and NH4+-Nwas1.0~1.3and the average concentration of NO3--N was only4.9mg/L.⑸The Anammox process was achieved in a UASB reactor by using syntheticwastewater with salinity after operating for165days, with a nitrogen loading rate of130mg/(L·d) and a salinity of3.0g NaCl/L, by using normal activated sludge as theseed. And then, the reactor performed well when the concentration of nitrogen and thesalinity were gradually increased to the level of mustard wastewater, which could makethe average TN removal efficiency to be86.2%.⑹The effects of the combined process of anaerobic treatment in ASBBR, partialnitrification in SBR and ANAMMOX in UASB to treat with mustard wastewater wasefficient. The average organic loading rates of ASBBR, SBR, UASB were1.94,0.42,0.33kg COD/(m3·d) respectively; the average concentrations of COD in effluent of ASBBR, SBR, UASB were417,331,127mg/L respectively; the combined process couldreduce the average concentration of COD from3883mg/L in influent to127mg/L ineffluent,96.7%of the COD could be removed. The average nitrogen loading rates ofASBBR, SBR, UASB were0.113,0.216,0.209kg N/(m3·d) respectively; the averageconcentrations of TN in effluent of ASBBR, SBR, UASB were216.2,209.0,28.2mg/Lrespectively; the combined process could reduce the average concentration of TN from226.4mg/L in influent to28.2mg/L in effluent,87.5%of the TN could be removed. And,the combined process could reduce the average concentration of NH4+-N from81.9mg/L in influent to1.4mg/L in effluent,98.2%of the NH4+-N could be removed; Therewas mainly NO3--N in nitrogen of effluent and the average concentration was24.0mg/L.It is feasibility that the combined process of anaerobic treatment in ASBBR, partialnitrification in SBR and ANAMMOX in UASB was used to treat with mustardwastewater and the combined process can remove organics and nitrogen efficiently. Theresults of study will provide some scientific basis for industrial application of salinewastewater treatment by ANAMMOX and engineering practice of mustard wastewatertreatment by biological methods. |
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