Effects of Inorganic Passivators on Gas Production and Heavy Metal Passivation Performance during Anaerobic Digestion of Pig Manure and Corn Straw.

The treatment of livestock manure caused by the expansion of the breeding industry in China has attracted wide attention. Heavy metals in pig manure can pollute soil and water and even transfer to crops, posing harm to humans through the food chain. In this study, corn straw was selected as the additive and introduced into the anaerobic digestion. Sepiolite (SE), ferric oxide (Fe2O3), attapulgite (AT) and ferric sulfate (FeSO4) were used as passivators to compare the effects of these inorganic passivators on gas production and passivation of heavy metals during the process of the anaerobic digestion. When the dry mass ratio of pig manure to straw is 8:2, the gas production efficiency is optimal. SE, AT and ferric sulfate have a much stronger ability to improve gas production performance than Fe2O3. The total gas production increased by 10.34%, 6.62% and 4.56%, and the average methane production concentration increased by 0.7%, 0.3% and 0.4%, respectively. The influence of SE, AT and ferric sulfate on the passivation of heavy metals is much better than Fe2O3, and the fractions in biological effective forms of Cu and Zn reduced by 41.87 and 19.32%, respectively. The anaerobic digestion of mixed materials is conducive to the gas production and the passivation of heavy metals. Therefore, SE, AT and ferric sulfate are selected as composite passivators, and the optimal ratio of inorganic composite passivators i: AT 7.5 g/L, ferric sulfate 5 g/L and SE 7.5 g/L, according to the results of orthogonal experiments. This study can provide a theoretical basis for the safe application of biogas fertilizers.

Treatment of the terephthalic acid-containing wastewater using a biological-aerated filter.

In this paper, the biological-aerated filter (BAF) was employed to treat the wastewater containing terephthalic acid (TA). Factors that affected the efficiency of TA and CODCr removal were evaluated experimetally, including pH, hydraulic loading, hydraulic retention time (HRT) and TA volume loading. At pH 7-8, hydraulic loading rate 0.067-0.48 m3/(m2 h), HRT more than 3.5h and TA loading 0.04-0.15g/(m3 d), the TA and CODCr removal efficiency was more than 93% and 87%, respectively. The mathematical model of matrix (TA) was obtained by Monod's relation and the experimental parameters of the model were 1.972 g/(m2d) and 9.782 mg/L.

[Diuron degradation process and change of toxicity by gamma-irradiation].

The radiation-induced degradation process of diuron and change of toxicity by gamma-irradiation were investigated. The contribution to diuron degradation by the radicals is in the order of: *OH > e(aq)(-) > *H. The quantum efficiency ratios of *OH, e(aq)(-) and *H for the degradation of diuron are calculated as 3 : 1 : 2. e(aq)(-) and *H could reduce diuron and its degradation product by loss of the chlorine atoms and the addition reaction. Both the shift and alkaline substitute mutations firstly increase and then decrease with the increase of irradiation time. But, the sample only shows mutagenic potential in Ames assay (TA100 strain) when 22.2 min is selected as the irradiation time. The acute toxicity firstly decreases and then increases with the increase of irradiation time and the more toxic substances are produced.