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Application Of Anaerobic Treatment And Bioconversion In Sweet Potato Wastewater

Posted on:2016-06-16Degree:MasterType:Thesis
Country:ChinaCandidate:F WangFull Text:PDF
GTID:2191330461483616Subject:Environmental Science and Engineering
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Our country is the world’s largest sweetpotato producer, The annual output of sweet potato exceeded 100 M tons. A huge amount of SPSW with high COD and N、P content which discharge directly may caused a serious environmental problem. The popular way to treat the starch wastewater is energy consumption if reach the standard of discharge, which not conducive to the development of sweet potato industry. On the other hand,SPSW contains high concentrate of starch、carbohydrate and other organic substances could be a culture medium for microorganism cultivation. This paper is concentrated in the way of SPSW resourcezation. The pilot tests of ABR treatment was conducted to treat SPSW, which was used to take place of the combination of anaerobic and aerobic treatment. The feasibility of ABR to treat the SPSW and the production status of biomass gas were discussed. Meanwhile, the biofertilizer by the resource recycling of sweet potato starch wastewater and application of vegetable planting were also achieved, its impact on vegetable output and environment physicochemical properties were studied. Through this study, the following conclusions can be summarized:It is feasible for the starting of ABR in normal temperature. The ABR had been running for one year. The date show that the COD removal efficiciency of anaerobic baffled reactor(ABR) achieved 76.2~94.1% and its production of hydrogen and methane reached 0.70-1.33 L/h and 0.60~1.13 L/h, respectively. The operating temperature was a key factor influencing the ABR treatment. As drop of environmental temperature, the ABR’s COD removal efficiency decreased either. When winter comes, the ABR’s COD removal efficiency decreased seriously. The deterioration of the ABR reactor can be mitigated by increasing HRT and reducing volumetric loading rates. Hence, some heat preservation measures are needed to ensure the efficiency of ABR treatment in case of low temperature. It is showed that ABR reactor has a high discharge efficiency at 29℃,which could be used as reaction temperature. ABR effluent showed a higher capability in promoting the vegetable growth in comparison with the traditional fertilizer. So the anaerobic technology could be feasible in agriculture areas.The Bacillus amyloliquefaciens A3 is a kind of PGPR, which can promote plant growth and inhibit a good control of plant pathogenic. This paper showed that the biomass of Bacillus amyloliquefaciens A3 by using SPSW could achive 2.74×109CFU/m L, which reaching the requirement of agro-microbial agent national standards(GB20287-2006)(viable bacteria count ≥2×108 cfu/m L). Meanwhile the cultivation of Bacillus amyloliquefaciens could also remove COD contents of SPSW.This paper discussed the feasibility of the Bacillus amyloliquefaciens biomass from SPSW used as biofertilizer, which were used for water spinach cultivation compared with urea. The results of a greenhouse randomized pot experiment show that the UN treatment provided the largest yield of vegetable. Moreover, the highest vegetable NO3- content, higher potential risk for soil nitrate leaching, and higher N2 O emission may have negative influence on environment. The inoculants used as biofertilizer could enhance the growth of vegetable, but the yield of BF significantly lower than urea treatments, hence biofertilizer could not replace N fertilizer completely. However, biofertilizer combined with chemical fertilizer treatment obtain low vegetable NO3- content and low N2 O emissions, reduce nitrate leaching and gave approximate similar enhancement of vegetable yield compared with UN treatment, which may be a practicable way for SPSW utilization. In addition, BCM treatment(B amyloliquefaciens inoculants with 90% fertilizer) reduced NO3- content of vegetables by 81.2% and N2 O emissions by 50%, which was regarded as the best one compared with other treatments.
Keywords/Search Tags:sweet potato starch wastewater, ABR, Bacillus amyloliquefaciens, water spinach, ABR discharge, N2_O
PDF Full Text Request
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