| The strategic concept of sewage recycling and carbon neutrality promotes the transformation and upgrading of the traditional sewage treatment industry that uses energy to exchange water quality.How to fully tap and utilize the organic carbon source in sewage and realize resource recovery is the frontier direction of future urban sewage treatment research.It is also an effective way to achieve carbon neutrality in wastewater treatment plants.The carbon source concentration of urban sewage in China is generally low.Therefore,it is necessary to develop carbon source enrichment and resource recycling processes according to local conditions to maximize the recovery of sewage organic energy.This project proposes the use of high-efficiency carbon source concentration technology ideas based on forward osmosis membrane separation,and develops a coupled coagulation/adsorption enhanced forward osmosis membrane concentration process,which realizes the effective enrichment of carbon sources in urban sewage and enhances the concentration of FO membranes The operation mode of the process is optimized,the feasibility of stable enrichment of the reactor is investigated,and the anaerobic resource utilization potential of the carbon source concentrated liquid is initially explored,provide theoretical reference for my country’s sewage treatment to achieve carbon neutrality.The thesis first studied the effect of seawater as a draw fluid to drive the forward osmosis system to enrich the carbon source of urban sewage,and investigated the changes in the operating characteristics of the system under different membrane orientations and cross-flow speeds,as well as the two FO membranes of CTA-ES and TFC-ES.The performance of separating and concentrating pollutants shows that seawater as a draw fluid can provide a more stable operation effect,and the flux is more stable in the AL-FS mode;TFC membrane has higher pure water permeability and salt repellency,CTA The membrane has better pollutant retention and concentration and enrichment efficiency than TFC membrane,and the final COD concentration of enrichment can reach 2660 mg/L,but the concentration factor is lower than the theoretical value.The concentration effect of the forward osmosis process on the carbon source is strengthened by compounding the coagulant/adsorbent.The results show that the prefabricated chemical floc mud cake layer filtration on the membrane surface can stabilize the membrane flux and effectively control membrane pollution.When combined dosing of 80 mg/L PAC and 40 mg/L activated carbon,the COD removal rate of the coagulation-FO membrane reactor can reach 97.2%,and the COD concentration in the concentrate can reach 4600 mg/L,which is significantly better than positive Permeation directly concentrates the enrichment effect of the sewage carbon source,and at the same time,the decrease of membrane flux is reduced.Stable enrichment can be achieved when the ratio of discharged concentrated liquid/influent water is controlled at 2.5～5%.The COD concentration in the reactor can be achieved during long-term operation.Maintained at about 4000 mg/L.Finally,through the anaerobic biochemical methane production potential test,the resource utilization effect of the carbon source concentrated liquid produced by the coagulation-FO membrane reactor was investigated.The results showed that the anaerobic gas production performance is greatly affected by HRT.When the mud ratio is 2/5 and the HRT is 24 h,the methane production efficiency is the highest.The ammonia nitrogen enriched in the carbon source concentrate will promote the anaerobic gas production process,while the chloride ion of the reverse osmosis will inhibit the activity of some methane bacteria,and the inhibition is dominant.Sludge domestication can improve the tolerance of anaerobic microorganisms to chloride ions.The methanogenesis potential of the final concentrate is 292 m LCH4/g COD,which is higher than the anaerobic resource potential of activated sludge and other biological flocculation carbon capture. |
