| The research aims to realize the centralized,efficient and low-cost treatment of wastewater from washing enterprises and break through the degradation of high concentration sodium dodecyl sulfate（SDS）wastewater,and meanwhile,to solve the current problems of inefficient and unstable degradation of SDS by single strain and composite bacteria.This study sampled the muddy water from the wastewater biochemical treatment pond of Hunan Lichen Industrial Co.,Ltd.,SDS used as the limiting factor,and selected the aerobic aeration to domesticate activated sludge and the shake flask gradient to domesticate,cultivate and screen the composite bacterial line.The efficient degradation bacteria were isolated and purified from the composite bacterial line,and the removal effects of the composite bacterial line and degradation bacteria on SDS,COD,TN and NH3-N in SDS inorganic salt medium were investigated.To investigate the degradation characteristics of the composite bacterial line and the degrading bacteria through single-factor experiments,the microbial diversity of the SDS composite bacterial line was analyzed by Illumina Miseq high-throughput sequencing technology.The ion chromatograph,liquid chromatograph and gas chromatograph were used to detect the intermediate and final products of SDS degradation by the composite bacterial line and degrading bacteria respectively and to speculate the metabolic pathways.the compatibility experiment of functional microorganisms was conducted according to the metabolic pathway,obtaining the SDS high-efficiency degradation bacterial agent,then use the two immobilization methods of adsorption and embedding to prepare the immobilized bacterial agent,and put it in the SBR device.The efficacy of bioaugmentation technology in treating SDS wastewater was investigated and the following results were obtained:1.Two highly efficient degradation consortia,SDS1 and SDS3,with SDS as the only carbon source,were screened from the aerobic tank.After gradient domestication and 15 times stable passages,the degradation performance of SDS1 and SDS3became stable.After 48 hours incubation,with an initial concentration of 1600 mg·L-1of SDS,a shaking speed of 180 r·min-1and the temperature 30℃,the degradation rates of SDS1 and SDS3 were 92.9%and 92.2%,respectively.66.7%,38.3%and16.2%of COD,NH3-N and TN were respectively removed by SDS1,while 59.5%,32.5%and 19.6%of COD,NH3-N and TN were respectively removed by SDS3.A strain of SDS-degrading bacteria D2 was isolated and purified from SDS1,and after gradient domestication and 15 times stability passages,it was found that D2 degraded94.2%of SDS and removed 68.3%,35.5%,and 12.8%of COD,NH3-N,and TN,respectively,after 48 h of incubation at an initial concentration of 1200 mg·L-1of SDS and a shaking speed of 180 r·min-1at 30℃.The results of 16S r RNA gene sequencing showed that D2 was 91%similar to Para burkholderia tropica（No.NR＿028965.1）,and D2 was identified as Para burkholderia tropica according to 16S r RNA gene analysis.2.It was found that,during the research on the degradation characteristics of SDS1,SDS3 and D2 on SDS,when the loading volume was 20%-100%,the inoculum volume was 1.5%-2.5%,the shaker speed was 120 r·min-1-200 r·min-1,the applied nitrogen source was sodium nitrate and ammonium chloride,and the initial concentration of SDS was 400 mg·L-1-1600 mg·L-1or 200 mg·L-1-1200mg·L-1,and the effects of SDS1,SDS3 and D2 on the degradation of SDS were small.The orthogonal experiments showed that temperature,p H,time and salinity were the most influential factors to the degradation of SDS by SDS1,SDS3 and D2.The optimal conditions for the degradation of SDS by SDS1 and SDS3 were all 30℃,p H7,time 48 h and salinity 0.05%.Based on the magnitude of the R-value,it can be seen that the influence of each factor on the degradation of SDS by SDS1 and SDS3,respectively,was in the following order:temperature>p H>salinity>time.The optimum conditions for the degradation of SDS by D2 were 30℃,p H 7,time 48 h,and salinity 0.1%.According to the magnitude of R-value,the effect of each factor on the degradation of SDS by D2 was in the following order:temperature>time>p H>salinity.The results of the orthogonal test were verified that the degradation rates of SDS by SDS1 and SDS3 were increased to 97.5%and 97.3%,respectively,at the initial concentration of 1600 mg·L-1of SDS after 48 h of incubation at 30°C,p H 7,salinity 0.05%,inoculum volume 2%,loading volume 50%,shaker speed 180r·min-1,and additional nitrogen source of sodium nitrate and ammonium chloride.The degradation rate of SDS by D2 was increased to 98.3%at the initial SDS concentration of 1200 mg·L-1.3.The results of microbial diversity analysis of SDS1 and SDS3 on SDS revealed that the dominant bacteria in the bacterial domain at the phylum level for SDS1 and SDS3 are Proteobacteria with a relative mean abundance of up to 98%or more.The dominant bacteria in SDS1 and SDS3 at the genus level were identical,which is Burkholderia-Caballeronia-Paraburkholderia,with a relative average abundance of more than 97%.The dominant fungi in the fungal domain at the phylum level for SDS1 and SDS3 is Ascomycota,with relative mean abundance upwards of 71%.At the genus level,the dominant fungi of SDS1 and SDS3 are also identical,both being Zopfiella with a relative average abundance of about 10%.4.The degradation pathways of SDS1,SDS3 and D2 on SDS were found to be identical,with SDS1,SDS3 and D2 degrading SDS by the hydrolysis of SDS ester bond breakage to produce sulfate and 1-dodecanol,1-dodecanol being partially oxidized to dodecanal,dodecanal being partially further oxidized to dodecanoic acid,dodecanoic acid being continuously oxidized byβbreaking to short-chain acids（acetic acid）,and acetic acid is finally mineralized to carbon dioxide and water.5.At a temperature of 30°C,p H 7,salinity 0.05%,loading volume 50%,inoculum volume 2%,shaker speed 180 r·min-1,with sodium nitrate and ammonium chloride being the applied nitrogen source and with the initial concentration of SDS being 1400 mg·L-1,the degradation rate of activated sludge to SDS was 89.0%after48 h;the initial concentration of SDS being 1700 mg·L-1,the degradation rate of H3（the ratio of SDS1 to D2 was 7:3）and K3（the ratio of SDS3 to D2 was 7:3）to SDS was 81.8%and 81.5%after 48 h,respectively.The degradation rates of SDS by H3（7:3 ratio of SDS1 to D2）and K3（7:3 ratio of SDS3 to D2）after 48 h were 81.8%and 81.5%,respectively;the initial concentration of SDS being 1800 mg·L-1,the degradation rates of SDS by H3 and K3 reinforced activated sludge after 48 h were87.8%and 84.7%,respectively,and the degradation rates of SDS by activated carbon fixed H3 and K3 were 90.5%and 90.2%,respectively.When the activated sludge was strengthened with immobilized bacterial agents H3 and K3 in SBR units R2 and R3,respectively,and incubated for 24 h at 30°C,p H 7,inoculated with immobilized bacterial dose of 2%,initial concentration of SDS of 3000 mg·L-1,and additional nitrogen source of sodium nitrate and ammonium chloride,the degradation rates of SDS by R2 and R3 both reached 89.9%,and the degradation rates of COD,TN,NH3-N by R2 were 89.5%and 84.7%,respectively.The removal rates of R2 for COD,TN and NH3-N were 89.5%,75.3%and 91.9%,respectively;the removal rates of R3 for COD,TN and NH3-N were 88.2%,72.4%and 90.6%,respectively. |
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