Study On Treatment Of Sulfur Autotrophic Denitrification Coupled With Anammox For Fermentation Wastewater

The fermentation industry occupies an important position in China’s industrial production.With the rapid development of the industry in recent years,the problem of huge amounts of wastewater discharge has attracted widespread attention.For fermentation wastewater,the current industry’s"anaerobic/aerobic"solidification treatment mode has four major problems:non-compliance,waste of resources,high cost,and huge carbon emissions.In order to solve the bottleneck problem in the industry,this study proposes the coupling system of anaerobic ammonia oxidation-sulfur autotrophic denitrification（CANON-SAD）based on the sulfur cycle:Based on the anaerobic ammonia oxidation process,the hydrogen sulfide in the biogas produced by the anaerobic pretreatment or the sulfur of the biogas desulfurization product is recovered and reused to replace the traditional carbon source for deep denitrification.Firstly,the feasibility study of the coupling system was carried out at the level of experimental water distribution and actual wastewater.Secondly,a kinetic model of pollutant degradation was established for the system and microbiological analysis was carried out.Finally,a pain point survey was conducted for a typical fermentation enterprise.The cost benefit of the coupled system is proved through cost calculation,and the conclusions are as follows:（1）The coupling system is feasible.Under stable operation,the NH₄⁺-N removal load of the coupling reactor is maintained at 0.31～0.39 kg/（m3·d）,and the NO₃^--N removal load of the SAD reaction system is 0.31～0.38 kg/（m3·d）;under short-term high sulfur impact,the SAD system can restore pollutant removal efficiency within 14days;short-term high sulfur impact on the nitrogen removal efficiency of the SAD system is higher than that of sulfur;when the SAD system has a sulfide intake concentration of 80 mg/L（S/N=1.1）and 120 mg/L（S/N=1.6）,the sulfur production rate is 11.6%～21.7%and 59.3%～70.0%,respectively.（2）Elemental sulfur supported autotrophic denitrification（ESSAD）reactor does not require sludge inoculation and can be quickly started within 5 days;the optimal HRT is 3.7 h,and the influent NO₃^--N is 34.41±4.23 mg/L with an average removal rate of about 93.5%;backwashing or sludge removal can improve the system’s pollutant removal efficiency but excessive and frequent backwashing is not required;adding an appropriate amount of carbon source can effectively reduce system NO₂^--N accumulation,reduce SO₄^2-production and ease system acidification.（3）Under the condition of sulfide concentration of about 80 mg/L（S/N=1.1）,the degradation of pollutants in the SAD reactor conforms to the first-order kinetic equation:_tC=0.9779C₀ e^{-1.6 34t},variance R²=0.9889.When the NO₃^--N concentration in the inlet water of the ESSAD reactor is≥36.1 mg/L and the HRT≤1.6 h,the reaction order is 0;when the NO₃^--N concentration is reduced or the HRT increases,the bottom removal rule conforms to the 0-order reaction and the top meet 1/2-order reaction;the lower the NO₃^--N concentration,the longer the HRT and the more consistent the removal rule is with the 1/2-order reaction.（4）Sulfurimouas and Thiobacillus have the highest abundance in the SAD system flora,accounting for 46.7%and 21.3%in the late stage III,respectively,and 52.3%and20.0%in the late stage V;short-term high-sulfide shock and increasing sulfide concentration has little effect on the microbial population structure of the reaction system.Truepera is dominant in the ESSAD reactor,and some of the bacteria in the genus can perform autotrophic denitrification;the main functional bacteria of sulfur autotrophic denitrification are Thiobacillus and Sulfurimonas;the presence of Rhodocyclaceae and Bacillus in the reaction system proves that it has both sulfur autotrophic and heterotrophic denitrification function.（5）The processing costs of AO process system,anaerobic ammonia oxidation system（CANON process）and desulfurization process system in typical fermentation enterprises are 9.99,2.93 and 0.46 yuan/ton of water,respectively.Applying the coupling system on the basis of the anaerobic ammonia oxidation system,the hydrogen sulfide driven CANON-SAD system can further reduce costs for enterprises by 0.34～0.69 of water,totaling 1.86～3.78 million yuan/year and sulfur-driven system can reduce cost by 0.36 yuan/ton of water,totaling 1.97 million yuan/year.