Research On The Effect Of Sludge Adsorption Coupling Iron Salt Coagulation Process On The C/N/P Enrichment Efficiency Of Sewage And Fe(?) On The Characteristics Of Carbon-rich Sludge

Our country's domestic sewage has a large discharge volume and a low degree of treatment.It fails to make full use of the abundant water and organic resources stored in the sewage,and cannot meet the current demand for energy saving and emission reduction.The transition from "waste" treatment to "resource energy" recovery is an important development trend of domestic sewage treatment in the future.In view of the problems of high energy consumption in traditional urban sewage treatment processes and insufficient recycling of organic matter resources in sewage,this topic proposes a process of sludge hunger adsorption coupling iron salt enhanced coagulation to transform sludge sewage from harmful products into resource and energy substances The carrier of enrichment captures the C/N/P in the sewage to improve the effluent quality of the sewage treatment plant to the reuse standard,and transforms the traditional sewage treatment process from the net energy consumption process to the energy output process.Conduct research on the enhancement of the C/N/P enrichment efficiency of sludge in sewage sludge concentration,iron salt dosage,process coupling method,etc.,and conduct an in-depth study on the characteristics of iron-based carbon-rich sludge to resolve iron salts The strengthening effect of coagulation on the carbon-enriched efficiency of sludge,to investigate the resource and energy recovery prospect of sewage.This paper proposes a "sludge adsorption" coupled with "iron salt coagulation" pollutant enrichment process,which aims to efficiently capture and enrich the organic matter in sewage.In addition,the effect of iron salts on the properties of carbon-rich sludge was analyzed,and the internal mechanism of iron-based carbon-rich sludge adsorption and capture of organic matter in sewage was analyzed.The two enrichment processes of "Sludge starvation adsorption" and "Sludge starvation adsorption coupled iron salt enhanced coagulation" were used to study the capture efficiency of C/N/P in sewage.The investigation found that when the sludge concentration is 1500 mg·L-1,the optimal enrichment rate of COD in sewage can be obtained 47.93%,which can effectively capture the colloidal and particulate COD in domestic sewage,but the The enrichment ability is weak,and it can only intercept 24.9% of ammonia nitrogen and 14.7% of total phosphorus.The coupling potential of the coupled ferrous salt enhanced coagulation of sludge is significantly higher than that of raw sludge.Among the three iron coagulants,Fe Cl 3·6H2O has better particulate COD adsorption efficiency than PAFC and PFC.The sludge adsorption was carried out before chemical coagulation,and then the coupling method of adding 30 mg·L-1 Fe³⁺ had the highest enrichment rate of COD,ammonia nitrogen,and total phosphorus in sewage,which could reach 78.96%,40.05%,and 95.47%,respectively.The characteristics of raw sludge and iron-based carbon-rich sludge were studied in terms of physical and chemical properties and surface characteristics.The results show that,compared with the original sludge,the organic matter content of carbon-rich sludge increased by 23% after the addition of Fe³⁺;when the dose of Fe³⁺ exceeded 30 mg·L-1,the colloidal structure formed by the hydrolysis of Fe³⁺ restricted the cells in the sludge flocs.With the extension of the outer polymer,the sludge particle size is reduced by 11.9%.In addition,Fe³⁺ may combine with electronegative groups in the floc sludge,which in turn causes the sludge particle size to decrease.The maximum negative surface charge is reduced by 28.9%,and the maximum surface density is increased by 75%.The adsorption sites are increased,which is conducive to bacterial implantation and absorption of organic matter in fixed sewage,and promotes the migration and transformation of sewage organic matter into the sludge phase.The strengthening effect of Fe³⁺ in iron salt on the carbon-enriching efficiency of sludge was studied.According to the analysis of EPS fluorescent staining results,the content and distribution of the internal components of the sludge floc changed due to the combined effects of Fe³⁺ electrical neutralization and adsorption-bridging,and the carbon-rich sludge formed the “protein outer membrane-? polysaccharide core” The double-layer structure of DO is concentrated on the surface,which proves that the iron-based carbon-rich sludge has a compact structure and a short transition area,which is not suitable for microbial dissociation;combining the iron-based carbon-rich sludge with the original sludge resistance to hydrolysis strength and resistance Shear strength research shows that the sludge flocs not only have adsorption capacity and are difficult to resolve and release the adsorption phase,but also have a certain structural integrity.Compared with the loose structure of the original sludge,it is more conducive to resisting external impacts and conducive to flocculation and sedimentation.Investigate the effect of the dose of Fe³⁺ on the microbial activity and community structure of carbon-rich sludge.The results show that when the dose of Fe³⁺ does not exceed 30 mg·L-1,the dehydrogenase activity and specific aerobic rate are both increasing.The increased microbial activity of the sludge is beneficial to the oxidation of organic matter in the sewage by the bacteria;but the ammonia uptake rate is not ideal,proving that the iron salt coagulation has little ef fect on the adsorption of ammonia nitrogen in the sludge.In addition,if the Fe³⁺ residue reaches a certain concentration,it will also cause toxicity to microorganisms,which in turn will lead to poor effect of activated sludge on the capture and enrichm ent of organic matter in sewage.This study shows that the “sludge starvation adsorption coupling iron salt enhanced coagulation” wastewater energy recovery process utilizes the bioflocculation of starved sludge cells and colloidal EPS on particulate,coll oidal and dissolved organic matter,combined with chemical coagulation The strengthening effect can realize the rapid capture,enrichment and storage of C/N/P and other energy resources in sewage,and produce iron-based carbon-rich sludge with high resource and energy recovery potential,which lays the foundation for the development of new sewage energy recovery processes.This study can provide theoretical and technical support for the recovery of carbon sources and to reveal the internal mechanism of iron salt coagulation to strengthen the carbon rich in sludge in the future.