Study On The Effect Of Compatible Solutes In Enhancing The Anaerobic Biological Treatment Of High Salt Wastewater

High-salt wastewater refers to wastewater with a total dissolved solids of at least 3.5%,which not only contains a large amount of inorganic ions,but also contains refractory organic compounds such as phenolic compounds,hydrocarbon compounds and dyes.They come from a wide variety of sources,mainly from tanning,textile,pharmaceutical,aquaculture,petroleum industry,food processing and other industries.Currently,the more commonly used treatment methods are physical method,chemical method and biological method.Compared with physical methods and chemical methods,biological methods have higher efficiency in treating high-salt wastewater without causing secondary pollution.However,too high salinity will inhibit the growth and metabolism of microorganisms,thereby affecting the activity of microorganisms.However,in high-salt environment,compatible solutes can accumulate in microbial cells at high concentrations without affecting the normal physiological functions of biological cells.Therefore,adding compatible solutes can enable microorganisms to grow and metabolize normally in a high-salt environment,thereby improving the biological treatment effect of high-salt wastewater.Based on the above background,This paper firstly studies the effect of three single compatible solutes of betaine,trehalose,and glutamic acid on the enhanced anaerobic treatment of high-salt wastewater,and on this basis,studies the effect of the mutual mixing of compatible solutes on the enhanced anaerobic granular sludge the effect of treatment.Then,the concentration of the three compatible solutes was used as the independent variable,and the concentration ratio was optimized by response surface analysis.Finally,16 S r RNA sequencing technology was used to compare and analyze the differences in microbial flora of some sludge samples to clarify the influence of compatible solutes on the anaerobic microbial flora.The main findings were as follows:(1)Investigate the effect of enhanced anaerobic treatment with a single compatible solute by using artificial simulation of salt-containing organic wastewater.The results showed that the increase in salinity has the significant impact on the anaerobic removal effect.However,when the salinity was increased to 20 g/L,the addition of betaine,trehalose and glutamic acid has a significant improvement effect on the anaerobic treatment effect and anaerobic sludge activity,among which the effects of these three compatible solutes The order was trehalose>betaine>glutamic acid.(2)By examining the COD removal rate,effluent VFA,daily gas production and dehydrogenase content and other indicators,the effect of the mixing of betaine,trehalose and glutamic acid on the treatment of high-salinity wastewater by anaerobic sludge was studied.The results showed that in the NaCl salinity wastewater environment,adding 0.5 mmol/L betaine + 0.5 mmol/L glutamic acid has a stronger effect on improving the anaerobic treatment capacity than 1 mmol/L betaine and 1 mmol/L glutamic acid.In the KCl salinity wastewater environment,adding 0.5 mmol/L trehalose + 0.5 mmol/L glutamic acid to improve the anaerobic treatment capacity is higher than 1 mmol/L trehalose and 1 mmol/L glutamic acid,and The addition of 0.5 mmol/L betaine + 0.5 mmol/L glutamic acid has a stronger effect on improving the anaerobic treatment capacity than 1 mmol/L betaine and 1mmol/L glutamic acid.(3)This study explored the optimal concentration of betaine,trehalose and glutamic acid to improve the anaerobic biological treatment of 20g/L high-salt wastewater,the concentration of three compatible solutes were used as independent variables,and optimize its ratio through response surface analysis.The results showed that: in the 20 g/L NaCl salinity wastewater environment,when the concentration of betaine,trehalose and glutamic acid is1.71,0.73 and 1.16 mmol/L,the anaerobic treatment has the best effect and COD removal The rate reaches 86.4%;in the 20 g/L KCl salinity wastewater environment,when the concentration of betaine,trehalose and glutamic acid is 2.12,1.15 and 1.84 mmol/L,the anaerobic treatment effect was the best,the COD removal rate reached 80.3%.(4)Five sludge samples were collected,i.e.Y1(0g NaCl/L),Y2(20g NaCl/L),Y3(20g NaCl/L with the compounding compatible solutes),Y4(20g KCl/L)and Y3(20g KCl/L with the compounding compatible solutes).16 S r RNA sequencing was conducted to elucidate the biodiversity and community composition.The results showed that the species composition of the anaerobic flora of each sample was similar,but the relative abundance was significantly different.The 16 S r RNA sequencing results also showed that Proteobacteria,Bacteroidetes,Thermotogae and Chloroflexi have strong tolerance to high-salt environments,while Euryarchaeota is extremely sensitive to salinity,but add the compatible solutes in mixed proportions can effectively alleviate the adverse effects.