| Recent years, with the rapid growth of municipal solid waste, some cities have been faced with the plight of “Garbage surrounded the city”. Traditional solid waste collection and simple landfill treatment can’t meet the requirements of environmental protection, the disadvantages are increasing more and more fast. Municipal solid waste classification collection is to achieve waste reduction, recycling and harmless of the most effective measures, it is also a best choice to crack the problem of solid waste siege and also become the inevitable choice of solid waste management. Classified collection as a key link in the process waste disposal has met with some problems which is in the promotion of implementation constraints. This paper based on the project fund of ?Based on the principle of 3R waste recycling and application research ?, which is from Bureau of Science and Technology of Lanzhou Municipality, Studied the way classified collection and recycling of Lanzhou MSW. The conclusions are as follows:(1)Through literature analysis, mathematical modeling and the methods of field sampling analysis, forecast the Lanzhou MSW output, determine the Lanzhou MSW physical components and typical organic component ratio. Time series method and the grey model GM(1,1) forecast results are very consistent, By 2025, the Lanzhou MSW reached 1.48-1.5 million tons; Organic components in living garbage and recycling garbage was increased, the proportion of the organic waste emissions of 545700 tons, with high value of recycling of paper, plastic, rubber and metal reached 145500 tons, 170100 tons and 03450 tons, has higher classification recycling value.(2)Through the questionnaire survey way to fully understand the Lanzhou city residents’ environmental awareness, garbage classification, garbage fee payments will understand support degree, etc., for Lanzhou city proper garbage classification scheme design to provide the beneficial reference.(3)Proposed the system of ″full charge and integral return″ and a detailedly plan of Lanzhou city municipal solid waste classification collection and implementation The solutions throughout the system of ″full charge and integral return″, and discussed the solid waste classification principle, charging system, way of return integral and others key issue; it is expected by arousing public participation of Lanzhou city municipal solid waste sorting process much faster.(4)Do to garbage classification scheme economic cost-benefit analysis, garbage classification scheme economically feasible, benefit is very considerable. Through the classification, the mechanical sorting recycled garbage each year, direct selling can profit of 329.1681 million yuan(excluding collection and transportation cost); Class kitchen waste composting treatment can be a profit of 16.01 million yuan. For classification of shunt throughout the year at least save landfill disposal costs 29.075 million yuan. Classification plan can save garbage a year 111.913 million yuan. Directly created profit is 165.8725 million yuan. The indirect social benefit, environmental benefit is obvious.(5)In order to solve the garbage problem, we put forward dealing with perishable organic waste by Anaerobic digestion technology. Temperature 36 degrees in experimental study on anaerobic digestion biogas production potential and digestive properties of typical organic components, get gas production potential(in terms of TS) and 310ml/g(measured in VS) 531 ml/g, have a high recycling value; Carbon-nitrogen ratio is moderate in the raw materials, the maximum concentration of ammonia nitrogen in about 1500 ml/g; and it is easily biodegradable substances of the class of typical organic components, easily lead to acidification of the system, anaerobic digestion, to select the right organic loading and control of PH value.(6)In feed TS concentration were 15%, 20%, 25% and 30% respectively four levels of high solid anaerobic digestion experiment, each of the four levels of high solid anaerobic digestion, has been a long time-acidification inhibits phase. With the increase of incoming TS, acidification inhibits growing recovery become more difficult; After PH regulation system for controlling access to the stable operation of 15% and 20%, it get to 2775ml/L·d and 813ml/L·d the maximum gas efficiency, 60-day cumulative gas production unit reactor is 29000 ml/L and 14800 ml/L; Feeding solid concentration TS is kept between 15%~20% and select an appropriate inoculation and proper PH control, resource of anaerobic digestion effect is significant.(7)Vaccination volume effects experiment showed that, when vaccination volume reached 70% digestive system does not appeared acidification inhibit phenomenon, and digest cycle almost shortened half; When vaccination volume 50% and 60% of digest reaction in organic large degradation VFAs cumulative rose period, need to lime the water regulation PH value to smooth completed anaerobic digest full process reaction; vaccination 30% and 40% of digest reaction, once stop regulation PH value on it will serious acidification led to digest failed. In order to ensure the treatment efficiency and gas production digestion efficiency, inoculation reached 50%(mass ratio) is appropriate.(8)In improving the efficiency of batch type anaerobic digestion reactor gas experiment, Seting up four different operating conditions, In stages twice operations is most significant. Average daily maximum production reach 3090ml/L each unit reactor, maximum cumulative gas production 35860 ml/L, cumulative gas production almost reached 520 ml/g·vs units materials experiment 5.3 raw material gas-producing potential; The stage of continuous production around the 25 th day digestion cycle is shortened to less than 50. The No. 2 and No. 3 which Add bentonite and attapulgite in the adsorption of H+ and PH buffer values did not show the desired effect, but compared with the No. 1 although it is short of suitable PH value control advantages, but entered the first stage of gas production. It may be the reason of add minerals to produce methane bacteria growth and reproduction provided attachment points, and promote the methanogenic population some extent. The promotion of this mechanism action is not clear, so require further experiments. |
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