Study On New Coupling Technology In Biological Removal Of Nitrogen And Carbon From Livestock Wastewater And Its Mechanism

In recent years, with the development of economy and the improvement of people’sliving standard, the demand for livestock and poultry products gradually increased,more and more manure wastewater was produced, manure wastewater pollution hasbecome one of the major pollution sources in the Three Gorges Reservoir and seriouslyharmed the water environment safety. Therefore, the technology of economic efficiencymanure wastewater treatment is urgent. At the same time, the technology would be goodfor protecting and improving the sub-tributaries and reservoir water environment.The removal of carbon and nitrogen are the keys in this research. Methanogenesis—Shortcut nitrification denitrification—Anaerobic ammonia oxidation （Anammox）and Simultaneous denitrification and methanogenesis （SDM）—Shortcut nitrificationdenitrification were introduced to treat manure wastewater for the removal of organicand nitrogen. Firstly, an investigation was to evaluate the performance of start-upreactor and the removal efficiency of organic and nitrogen by Anammox, SDM,shortcut nitrification denitrification respectively; Then both Methanogenesis—Shortcut nitrification-denitrification—Anammox and SDM—Shortcut nitrification-denitrification coupling technologies were used to treat high organic and nitrogenmanure wastewater. Research showed that the latter technology had good removalefficiency on organic and nitrogen, and it was applied to the demonstration project andgood results were obtained.Draw the following conclusions:①The start-up of Anammox reactor and the acclimation of activated sludgeIn order to realize nitrogen removal by Anammox pathway from the manurewasterwater, firstly, the start-up of Anammox reactor was achieved by application ofsimulated wastewater. Comparative anammox reactor start-up in different sludgeinoculation concentration, experimental results showed that the influent concentrationof NH₄⁺-N and NO₂^--N were340.74mg/L and340.97mg/L respectively in the sludgeinoculation concentration at53.23g/L, the average NH₄⁺-N, NO₂^--N and TN removalefficiency reached99%,98%and75%respectively. However, the influentconcentration of NH₄⁺-N and NO₂^--N were216.98mg/L mg/L and218.94mg/L mg/Lrespectively in the sludge inoculation concentration at31.94g/L, The average NH₄⁺-N,NO₂^--N and TN removal efficiency reached90%,50%and30⁴0%respectively and produced a lot of nitrate. Therefore, it is more easily to realize the start-up ofAnammoxreactor in high sludge inoculation concentration. By scanning electron microscopic andobserved that the two reactors contained spherical, rod-shaped, Anammox bacteria,indicated the successful realized start-up of Anammox reactor.②The start-up of SDM reactor and the influence mechanism on the removalefficiency of carbon and nitrogenNO₂^-N is the key influence in the removal of carbon and nitrogen throughsimultaneous methanogenesis and denitrification, then, the mechanism of NO₂^-Nrestrain the simultaneous methanogenesis and denitrification reaction was studied. Theorganic and nitrogen removal effect of wastewater treatment was studied in organicloaded3.0kgCOD·m-3·d^-1, and COD/NO₂^--N ratio of10:1,20:1,30:1,40:1, respectively.Studied the change pattern of COD, Coenzyme F₄₂₀, β-glucosidase, MLVSS/MLSS etcin the reactor by continuously monitoring, the conclusions can be obtained as followed:when COD/NO₂^-N as30:1and40:1, there had no obvious difference between thecontrast experiment and blank experiment, the activity of methanobacter would not berestrained; when COD/NO₂^-N as10:1and20:1, there had significant difference, theactivity of methanobacter would be restrained. SDM was studied under the condition ofpH=6.8⁷.6, T=35±1oC, and the COD/NO₂^--N=30:1of manure wastewater incontinuous stirred tank reactor. The loading rate of COD is3.0kg·m-3·d^-1, the removalefficiencies of COD and NO₂^--N were over70%and99%respectively after45d.③The removal efficiency of nitrogen by shortcut nitrification-denitrificationpathway from the manure wasterwaterThrough the nitrosation way to removal nitrogen is the important content in thisissue, so, two key points were studied.1) The influence parameters included pH, FAand aeration mode on the steady of shortcut nitrification-denitrification process wasstudied.2) It is found the proper pH and FA for shortcut nitrification–denitrificationwas8.0and18during the treatment process of anamial manure wastewaterrespectively, also it is found the NH₄⁺-N removal efficiency is with little difficiencebetween constant aeration rate and constant DO.④Organic and nitrogen removal by Methanogenesis—Shortcut nitrificationdenitrification—Anammox coupling technology from high organic and nitrogenmanure wastewater1) It is studied the start-up of methanogenesis reactor with manure wastewater. Theorganic loading rate and its removal efficiency reached3.5kg COD·m-3·d^-1and80% respectively.2) The Methanogenesis—Shortcut nitrification denitrification—Anammox coupling technology was used to treat anamial manure wastewater. Theorganic removal efficiency of this technology was more than92%and it had goodremoval efficiency on organic.3) The NO₂^--N/NH₄⁺-N ratio of Shortcut nitrification-denitrification effluent is between0.6and2.5, and the TN removal efficiency wasunstable, and it was55⁸0%.⑤Organic and nitrogen removal by SDM—shortcut nitrification–denitrification coupling technology from manure wastewaterThe coupling technology of SDM—shortcut nitrification-denitrification wasused to remove organic and nitrogen in manure wastewater. The organic and nitrogenremoval efficiency was evaluated under simulation circulation,1:1and2:1reflux ratio.The average organics, NH₄⁺-N removal efficiency reached95%and94%respectively insimulation circulation; the average organics, NH₄⁺-N, TN removal efficiency reached96%,95%, and86%respectively in1:1reflux ratio; the average organics, TN removalefficiency reached94%and89%respectively in1:1reflux ratio. To sum up,1:1refluxratio was the best choice, organics and TN removal efficiency reached70-80%and13%in SDM reactor; organics and TN removal efficiency reached16-26%and73%in theshortcut nitrification-denitrification⑥Demonstration project of SDM—shortcut nitrification-denitrification to treatanamial processing wastewaterThe start-up of demonstration project of SDM reactor was done throughdomestication experiment, organic removal efficiency was over70%through anaerobicmethanogenesis reactor, NH₄⁺-N removal efficiency was over80%through shortcutnitrification-denitrification reactor. According to the research conclusions obtainedformerly, the reflux ration was set as1:1, the organic removal efficiency was more than80%in the methanogenesis and denitrification reactor; the organic removal efficiencywas more than95%and the ammonia nitrogen clearance was more than90%in thedemonstration project system which indicated better removal efficiency toslaughterhouse wastewater of the combined process.