Strengthen The Technique Of Obtaining Alginate From Surplus Sludge

At present,the world is facing severe resource supply and environmental protection issues.With the popularity of sewage treatment facilities,the amount of sludge remaining in sewage treatment plants has increased rapidly each year,and the proper disposal of sludge has become a problem faced by various countries.Because of the high demand of alginate and the high price in the market,the sludge generated during the sewage treatment process contains a certain amount of alginate,and the extraction of alginate from the sludge can become a new use of sludge resources.direction.On the one hand,sludge reduction can be achieved.At the same time,alginate provides a new way to obtain the sludge.Research on the extraction of alginate from sludge is still in its infancy.How to obtain alginate from sludge efficiently is one of the focuses of the study.The method for extracting alginate from sludge is not yet mature.Different sludge forms,different sources of sludge,and the differences in the content and properties of alginate obtained remain to be studied.In this study,alginate was firstly extracted from the extraction method by optimizing conventional alginate extraction methods and establishing a new bacterial alginate extraction method.Then the technical means of strengthening the alginate were determined by investigating the effects of the sludge form?floc sludge,granular sludge?and the water quality of different sewage?sodium acetate,sucrose and phenol as carbon sources?on the content and characteristics of alginate in the sludge.The main results are as follows:In the study of alginate extraction by conventional methods,the effect of calcium coagulation ion exchange method to extract alginate was the best.The optimum extraction conditions were obtained by response surface method:the concentration of Na₂CO₃ was 6%,the digestion temperature was 70,the digestion time was 2 h,and the content of the net alginate in the sludge was 20.18 mg/g-MLSS.In the study of alginate extraction by new method,the content of alginate obtained by ultrasonic?50W?+NaOH method was the highest,and the content of net alginate was 45.65 mg/g-MLSS.From the above research results,it can be seen that granular sludge is beneficial for obtaining more alginate.In the study of alginate extraction from aerobic granular sludge in actual urban sewage cultivation and flocculent sludge from actual sewage treatment plant,the content of net alginate obtained by using ultrasonic?50W?+NaOH method to extract the granular sludge from municipal wastewater was the most?56.96 mg/g-MLSS?.The MALDI-TOF MS reflectance spectrum and infrared spectrum analysis showed that the alginate molecular weight range was about 199¹455 m/z,and alginate was composed of 8 monosaccharaides,bacterial alginate is similar to the characteristic peak of finished sodium alginate.According to the separation of different sections and acetylation degree,the content of mannuronic acid?M?and acetylation degree of floc sludge alginate were lower than those of granular sludge cultivated by domestic sewage,indicating that alginate had high strength and poor water holding capacity.In addition,the alginate extracted from flocculent sludge has the strongest ability to complex lead.In the study of the effects of different carbon sources on the extraction of alginate,the highest alginate content in the granular sludge with sodium acetate as the carbon source was obtained by ultrasonic?50W?+NaOH extraction,which was the highest at 59.81 mg/g-MLSS.The MALDI-TOF MS reflectance spectrum and infrared spectrum analysis showed that the weight average molecular weight and number average molecular weight of alginate in sludge cultured with phenol as carbon source by ultrasonic?50W?+NaOH method is 399.84 g/mol and 350.39 g/mol respectively.The characteristic peaks of alginate in granular sludge from different carbon sources are similar.According to the separation of different sections and acetylation degree,Sodium acetate and sucrose may affect the activity and content of enzyme AlgL in granular sludge.The alginate in Granular Sludge Cultivated with sodium acetate as carbon source contains higher MG section?42.78%?.The alginate in granular sludge with sucrose as carbon source contains higher GG section?5.55%?.Phenol as a toxic substance may inhibit the activity of core enzymes involved in acetylation,resulting in a low degree of acetylation?1.61%?.Among them,the content of c-di-GMP in granular sludge containing sodium acetate,sucrose,and phenol as carbon sources was 3.06?g/g-MLSS,2.16?g/g-MLSS,and 0.49?g/g-MLSS,respectively.Better promote microbial synthesis of more c-di-GMP,thereby promoting the secretion of alginate.In addition,sludge with sodium acetate as carbon source has better species richness,and sludge with phenol as carbon source has better species uniformity.Although Pseudomonas is the main source of bacterial alginate,its content in granular sludge is very low,and the relative abundances in the sludges of sodium acetate,sucrose,and phenol are 0.99%,0.78%,and 0.83%,respectively.It can be speculated that besides Pseudomonas can secrete alginate,there may be many microorganisms,such as Soxhlet,Clostridium and Arthrobacter,which can also secrete alginate.Based on the above findings,domestic sewage with sodium acetate as the carbon source is more conducive to the production of alginate.