| The anaerobic digestion treatment of municipal organic solid wastes is one of the processing technique for changing the waste to resource which accord with ecological principle,and it has been the developing direction of the treatment of organic solid waste. There are some disadvantages while using the current anaerobic digestion treatment of municipal organic solid wastes, such as low decomposition rate of the organic waste, long decomposability period, low biogas yield and poor methane yield in biogas. It can accelerate the decomposition of the organic waste and improve the biogas yield by adding some metal ions in the anaerobic digestion system, which results better effect for changing the waste to resource. In this paper, the study was conducted on the significant effect of three main metal ions as Fe, Co and Ni into the anaerobic digestion through orthogonal experiments, educed the best feasible promoter combination of Fe, Co and Ni , as while, the addition of metal ions to the hydrolytic dissolve-out of organic solid wastes -UASB combination process for treating the organic waste was studied. Several aspects were researched:①Three metal ions as Fe, Co and Ni, which have significant effect on anaerobic digestion system had been chose to anaerobic digestion system. Then carried through three effect factors and three levels orthogonal experiment as while as the experiment of Fe on one effect factor and several levels, and their promotion effect on anaerobic digestion system were studied. The influent of orthogonal experiment was the hydrolytic dissolve-out of organic solid waste, and the effect was evaluated according to anaerobic methane production. The experiment were conducted under these conditions that the organic load was controlled between 7.2～8.5 kgCOD/m3·d, the average unit methane production per day was 0.261～0.365 L/g COD. The results indicated that Co, Ni, Fe had a significant promotion to anaerobic digestion of hydrolytic dissolve-out, while the sequence of their effect was Co>Ni>Fe, and the optimum combination was Co2+of 5.0mg/L, Ni 2+of 1.0mg/L, and Fe2+of 1.0mg/L.②Further studies on the significant promotion of the addition of metal ions as K, Mg and Co, Ni ,Fe to the hydrolytic dissolve-out of organic solid wastes -UASB combination process were carried out. The promoter combination of K, Mg, Fe, Co, Ni ions was 100 mg/L K (KCl), 50 mg/L Mg (MgSO4·7H2O), 5.0 mg/L Fe (FeCl2·4H2O), 1.0 mg/L Co (CoCl2·6H2O), and 1.0 mg/L Ni (NiCl2·6H2O) respectively. Research results showed that addition of metal ions to the influent of UASB reactor gave a significant promotion to the anaerobic digestion. After the addition, the average volume load increased from 12.89 kg COD/ (m3·d) up to 17.79 kg COD/ (m3·d); the sludge load raised from 0.82 kgCOD/ (kgVSS·d to 1.07 kgCOD/ (kgVSS·d); and the removal of COD reached above 91.9%; Additionally, the biogas yield per kilogram COD was 392.5L, which was increased by 6.4%; while the methane yield per kilogram COD was 297.5L, which was increased by 10.5%. The experiments proved that adding promoter combination would availably reforme the disadvantages such as low decomposition rate of the organic waste, long decomposed period, low biogas yield and poor methane yield in biogas, and the methane yield raised finally. Compared with other interrelated researches at home and aboard, the UASB reactor was characterized by comparative good stability and recovery effect.
|
PDF Full Text Request