| The storage of municipal waste in garbage incineration power plant would produce plenty of leachate,which must be carried on pollution-free disposal to reduce environmental pollution. At present, it will commonly build a set of specialized leachate treatment process in domestic. According to the characteristics of incinerators' leachate,the anaerobic(CLR)-aerobic(HDR) was adopted as an important constituent of leachate biochemical treatment system, to investigate the feasibility and effect in engineering application in North China(low concentration)and East China(high concentration).What's more,it was calculated of the carbon emissions of leachate treatment engineering in east China, and put forward some suggestions according to the operation in the engeering.Taking the incinerator in North China as an example, the anaerobic(CLR)- aerobic(HDR) system in engineering application of low concentration leachate was investigated through analysizing the removal efficiency of COD and ammonia nitrogen. Anaerobic system successively went through twice loading-increasing: the first promotion via 120 days(normal temperature), the COD removal efficiency was more than 85% when the volumetric loading rate reached to 8 kg/m3·d, and the maximum biogas yield could be maintained about 2500m3 /d;the second raising via 20 days(Steam heating), the COD removal efficiency was more than 90% when the volumetric loading rate reached to 9.2 kg/m3·d, and the maximum biogas yield could be maintained about 2909 m3/d. The relationship between the biogas production rate and the volumetric loading rate or the amount of COD removal was analyzed, it revealed that biogas could increase about 0.28 m3 when the volumetric loading rate rose by1 kg/m3·d.Meanwhile,0.32 m3 biogas was generated when CLR anaerobic reaction consumed 1 kg COD. 87.5% of the influent COD was used to form biogas, and the rest of 12.5% COD was mainly used for microbial growth and the remaining in effluent. Simultaneous oxidation of COD and ammonia nitrogen could be realized in the underlying of the aerobic tank, and denitrification in the upper by controlling the dissolved oxygen, which could remove COD and ammonia nitrogen as well as reduce total nitrogen of the effluent. However,it also presented a lot of problems,such as unstable running, biomass loss and the low removal of total nitrogen.Taking the incinerator in the East China as an examples,the treatment effect of the high concentration of leachate was researched analysizing the the sludge concentration, the variation of volumetric loading and the operation condition deeply. By means of contrast with the North China example,it was analysized of the differences and optimized operation constantly for better removal rate. The running results of CLR systems showed the optimum operating conditions : volumetric loading is 8 ~ 10 kg/m3·d, upflow velocity is 0.3 m/h, hydraulic retention time is 4 ~ 5 d. Under these operating conditions,the VSS rose to 63 kg/m3, VSS/TSS went to the top of 80%, COD removal rate was over 90%, gas production was up to 4000 m3/d, the ph always kept balance. When the quantity of COD removal reached 10.1 kg/m3·d, gas production rate went up to 3.58 m3/m3·d; when the volumetric loading arrived at 10.9 kg/m3·d, the gas production rate attainned a maximum of 3.0 m3/m3·d. 80.6% of the inlet COD produced methane, the remaining 19.4% of COD was for the effluent surplus and microorganisms utilized. In the HDR system, the maximum volume loading of COD and ammonia nitrogen was respectively 2 kg/m3·d and 320 g/m3·d, and the effluent of COD and ammonia nitrogen was 800 mg/L and 40 mg/L after 100 days' running.In the first 80 days,the MLSS and MLVSS respectively increased from 4.5 g/L to 16 g/L and from 0.4 g/L to 0.4 g/L,and MLVSS/MLSS reached around 30%. Afterwards, the sludge concentration remained relatively stable. In order to get high removal efficiency of total nitrogen and COD persistently, it was necessary to increase the quantity of sludge reflux to maintain a high concentration of sludge, control the upper of aerobic tank dissolved oxygen at approximate 1 mg/L. Running results showed that the engeering in East China had a more stable operation, relatively low SS of anaerobic effluent, higher gas production rate, and better removal efficiency of total nitrogen compared with the engeering in North China.The organic carbon and nitrogen in anaerobic(CLR)- aerobic(HDR)- A2O2 process was traced and mass-balanced. We can calculate the carbon emissions of material, energy and material consumptions, and energy recovery for power generation through combining with the production process of chemical equation and empirical formula. The calculation results showed that the average carbon emission was 30528.35 kg CO2/d,annual emission by 1.11 × 107 kg of CO2, which the percentage rate of methane emission was 79%.If the biogas was used to generate power, can get 12104 kw·h/d, cutting down carbon emission directly and indirectly by 30743.5kg CO2/d.The amount of emission reductions was larger than the total carbon emissions.So the carbon emissions was negative value in the engeering,and the value was 215.15 kg CO2/d. Annual power generation was about 4.42 ×106 kw·h, reduceing carbon emission of 7.85×104kg CO2. |
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