Strengthen Activated Sludge Based On The Circulating Biochemical Tank Study On The Treatment Of Low-concentration Sewage Test

This article is based on the "operating principle of the closed continuous flow activated sludge process",with the main goal of "maximizing the microbial biomass"in the wastewater treatment process,and based on the existing aeration tank structure,the improved "And "internal circulation" as the main characteristics of the biochemical reaction system,designed and developed a closed double-inlet internal circulation biochemical tank that can realize multiple groups of parallel operation.The renovation project occupies land and provides a new way to reduce project investment.At the same time,the fly ash-enhanced activated sludge method(FA-AS)was used to treat low-concentration sewage from a sewage plant in Ma’anshan City.Through the comparative study of the FA-AS process and the activated sludge method(AS),the addition of fly ash was discussed in depth.The impact on the biochemical treatment system and its mechanism of action provide theoretical guidance and technical support for low-concentration sewage treatment.In order to screen out the powder particles that are easy to have considerable sedimentation performance in the biochemical tank,the fly ash was screened and characterized many times.The research results showed that the turbidity reduction process of the 1.5g/L fly ash mixed solution during the sedimentation process was determined by The turbidity drops the fastest in the first 30 minutes.After 120 minutes of sedimentation,the turbidity changes basically smoothly.Small particles of fly ash account for the main part of the water.This part of the particles is the main reason for the poor overall sedimentation performance of fly ash.;The greater the amount of fly ash added,the more screening times are required.The quality of the finally obtained fly ash only accounts for about 40% of the original fly ash;the particle size distribution of the fly ash after screening is uniform,and the particle size Mainly distributed between 20～55um;the particle shape is mainly regular spherical,and the inside mainly contains elements such as Al,Si,O,etc.The massive particles with a higher degree of surface wrinkles mainly contain C element,and the surface functional groups are silicon-oxygen bonds,The aluminum-oxygen bond is mainly non-polar,which has a certain affinity for activated sludge;the heavy metal content of the selected fly ash is determined,and the leaching rate of the five metal elements is low,and no excess is detected.The static test of the optimal dosage shows that when the dosage of fly ash is1.5g/L,the sedimentation performance of the sludge is the best,and the SVI value increases when the dosage is increased;at the same time,the pollutant indicators COD,The removal rate of NH4+-N and TP increased firstly and then decreased with the increase of the amount of fly ash added.At this time,the removal rates of COD,NH4+-N and TP were 75.31%,58.54% and 61.25%,reaching the extreme values.Continue to increase the dosage,but the removal effect will become lower.Comprehensive consideration has been taken to determine the optimal dosage of fly ash in the dynamic test is 1.5g/L.The FA-AS biochemical tank system has been operated in parallel with the traditional activated sludge system for 118 days under the optimal fly ash dosage.In the sludge cultivation and domestication stage,COD removal effect is the best,with an average removal rate of 64.27% and 67.88%,but due to the long contact time and mass transfer process between the microorganisms and the substrate,the processing capacity of the biochemical tank is excessive,and the biomass activity inside the tank cannot be maintained continuously,which affects the efficiency of the entire system for nitrogen and phosphorus removal.In the stage of changing the influencing factors of the biochemical tank,by comparing the treatment effects of the pollutants in the two systems under three different working conditions(increasing the aeration intensity,increasing the end inlet water concentration and changing the first and last inlet water flow ratio),it is found that fly ash is added to the pond to form fly ash-activated sludge(FA-AS system),which has a certain improvement in the effect of nitrogen and phosphorus removal compared with the traditional activated sludge(AS system).The current inlet water flow rate is 11.25 L/h,the terminal inlet water flow rate is 3.75L/h(the volume of raw water treated by the biochemical tank is 180 L,HRT=12h,and the optimal flow rate ratio is 3:1),and the aeration intensity in the aerobic zone is controlled at 1～1.5L/ min,the end influent concentration is stable at200±50mg/L,at this time,the performance of the simultaneous removal of nitrogen and phosphorus in the biochemical pond is the best.Through the changes in sludge characteristics and the influence of microbial phases and biological communities in the dynamic test,it is found that after adding fly ash,the biomass in the system increases faster and increases more than the traditional activated sludge,and the SVI changes also.The sedimentation performance has been greatly improved;At the same time,the microbial micelles and microbial flocs in the FA-AS system are densely attached to the surface of the mud and powder flocs,and the microbial growth has been significantly improved,and the entire domestication culture;In the experiment,the sludge morphology changes and the micro-animal characteristics in the two systems were examined under microscope.A total of 32 different micro-animals were observed and found.There are 30 kinds of protozoa.Among them,there are 2 species in the Mastigophora class,and the Sarcopodia(There are 2 species of Sarcodina,26 species of Ciliatea,and 2 species of micrometazoa.Through high-throughput sequencing,it can be found that in terms of similarity analysis,after adding fly ash,the sludge Compared with the traditional sludge,the number of sequences contained increased by 124;in terms of diversity analysis,after adding fly ash,the microbial diversity of the system was reduced,but the microbial community structure was not changed,but the adsorption effect of fly ash Promote the metabolic rate of microorganisms,improve the properties of activated sludge,and then improve the operating effect of the system;in terms of composition analysis,after adding fly ash,the composition of the flora is more comprehensive,and the number of microbial units in the sample reached 1,157 and1,099,the ecosystem composed of these flora and microorganisms can greatly improve the stability of the system itself and provide sufficient biodegradability for sewage treatment.