Q.-H. Wang’s research while affiliated with University of Science and Technology Beijing and other places

Based on the previous studies, in order to reduce the distillery waste form ethanol fermentation, the distillery wastewater of ethanol production from kitchen garbage was recycled in this study. Particularly, the accumulation of the by-product during the fermentation and their effects were investigated. The results indicated that ethanol fermentation was inhibited obviously by full-recycling distillery wastewater without treatment. After 4times full-recycling, ethanol production was decreased from 28.4 g/L to 2.56 g/L. With the increasing recycling times, lactic acid, SS, DS and salinity were accumulated to 5.45, 64.7, 99.5 and 12.3 g/L, respectively. In order to improve the recycle times, 2/3 partial-recycling mode and flocculation full-recycling mode were utilized. During 7times of distillery wastewater recycling, the ethanol productions maintained at the range of 25.5~35.5 g/L for 2/3 partial-recycling mode. While for flocculation full-recycling mode, the ethanol production maintained at the range of 12.2~32.4 g/L. 2/3 partial-recycling mode was superior to flocculation full-recycling mode. In future, the combination of the two recycling methods should be considered for further improving the distillery wastewater recycling system. © 2015, Chinese Society for Environmental Sciences. All right reserved.

Sanjiang plain, which is an alluvial land situated at the confluence of Songhua, Heilong and Ussuri Rivers in northeast of China, is an important commodity grain base. Within the confluence zone, the contents of five heavy metals (Cd, Hg, As, Pb and Cr) in surface soils were sampled and monitored in 21 villages around Tongjiang, Fujin and Suibin Cities. Spatial distribution analysis and assessment were conducted by using GIS technology, Müller geoaccumulation index and Håkanson potential ecological risk index. Heavy metal contents in the studied area range as follows: Cd, 0.048-0.280 mg/kg; Hg, 0.017-0.079 mg/kg; As, 4.73-18.16 mg/kg; Pb, 15.9-34.8 mg/kg and Cr, 16.8-55.1 mg/kg, indicating that the detection results meet the agricultural industry standard of China, i.e., environmental condition standards for pollution-free food production (NY5332-2006). Statistical analysis showed that there are certain correlations among Cd, As and Pb. In Fujing City, the southwest region of the studied area, Cd, As and Pb levels are elevated. Hg distribution is dispersed and Cr level is elevated in the eastern and southern parts of the studied area. Moreover, the calculations of Müller geoaccumulation index and Håkanson potential ecological risk index indicate that light pollution is caused by Cd and As and that the majority of the studied area is exposed to slight ecological risk.

Effects of different fermentation parameters including temperature, pH and oxygen on lactic acid (LA) production from kitchen waste were investigated in order to establish optimum regulating measures and increase LA yield. An open fermentation mode was employed for achieving simultaneous saccharification and fermentation of kitchen waste with Lactobacillus TY50 as inoculum. The results showed that 45 °C was optimum tem-perature for synergistic relationship between inoculated strain and indigenous strains, re-sulting in higher LA concentration. Continuous pH adjustment to 6.0 resulted in the sim-ilar LA concentration with intermittent pH adjustment to 7.0. However, LA productivity for continuous pH adjustment was much higher than intermittent pH adjustment. Com-pared to anaerobic fermentation, aerobic condition resulted in a decrease in LA concen-tration and an increase in acetic acid concentration. LA concentration could reach to 36.29 g L –1 with 1.01 g L –1 h –1 of productivity and 0.44 of yield (LA/dry mass) from kitchen waste fermented anaerobically by Lactobacillus TY50 at 45 °C and pH 5.5–6.0.

Plackett-Burman and central composite designs were employed to screen and optimize the significant factors for the enhancement of lactic acid production from kitchen waste. The results of Plackett-Burman experiments showed that lactic acid bacteria TD175, glucoamylase, tween80 and cellulase were the positive significant factors, while sterilization affected the fermentation negatively. Optimum conditions for the lactic acid fermentation of kitchen waste were determined by central composite design as follows: TD175 6.6%, glucoamylase 160 U/g, cellulase 60 U/g, Tween-800.08% and temperature 45 °C. Under these conditions, lactic acid concentration in the fermentation broth reached 66.13 g/L after 40 h, and about 0.53 g lactic acid was produced from one gram of dry kitchen waste. Lactic acid production from kitchen waste need not sterilization operation and extra nutrient, thus it is very economical.

The effectiveness of bioleaching is highly dependent on many biological factors. Four factors were investigated: sucrose concentration, spores concentration, fly ash concentration, and the time of fly ash addition. By using the central composite design, the non-linear equations, which described the relationship between the concentration of extracted heavy metals and the four factors above were obtained. Besides, the range of optimal bioleaching conditions were determined as follows: the concentration of sucrose, spores, fly ash was 114~126g/L, 1.6×107~2.1×107 spores/mL, 29~39g/L, respectively, and the time of fly ash addition was 3.6~4.4d. The trial was carried out in the optimum conditions by bioleaching 70g/L fly ash for 20 days. The concentration of extracted heavy metals was up to 901mg/L, which was 41% of the total heavy metals in fly ash.

Aimed at the preparation and property improvement of bipolar membranes used in water splitting electrodialysis technology, chloromethylation polysulfone and sulfonation polyphenylene oxide were taken as the anion exchange membrane layer and the cation exchange membrane layer, then the metal complex was fixed between them as catalyst to prepare three kinds of bipolar membranes: BPMSn0.1, BPMCr0.1 and BPMNi0.1. They were compared with the bipolar membrane without any catalyst fixed. Experimental results show that metal complex is effective catalyst for hydrolytic dissociation, and the electric potential is decreased greatly. The catalytic activity of three catalysts is as follows: Cr3+ > Ni2+ > Sn2+. The excessive amount of catalyst will increase the membrane resistance. The metal complex has little effect on selecting permeation; the adhesive force of catalyst with anion and cation layers is weak, and the falling off or dissolving of catalyst occurs in the electrodialysis process.

Dyeing wastewater was treated with a two-stage system of hydrolysis acidification and food chain reactor (FCR). The influences of hydraulic retention time (HRT) on the removal efficiency of COD, chromaticity, NH3-N and anilin were examined, and the mechanism and efficiency of nitrogen removal at the optimum HRT were discussed. When HRT was 30 h, the average removal ratios of COD, chromaticity, TN, NH3-N and anilin were 93.3%, 81.9%, 79.9%, 98.1% and 74.8%, respectively. The effluent average concentrations of COD, chromaticity, TN, NH3-N and anilin all met the first level of China Textile and Dyeing Industry Water Pollutants Discharge Standard (GB 4287-92). It is shown that this system, which not only removes both color and organic matter effectively, but also has great removal effect on nitrogen, can be used in treating high- and middle-concentration dyeing wastewater.

In order to avoid pollution caused by distillery waste from ethanol production by kitchen garbage, optimum conditions for glucoamylase production from such waste were determined in this study. Plackett-Burman design was utilized to screen the most influential factors of the fermentation medium. Corresponding optimum ingredients as well as conditions were studied. Then the produced enzyme was adopted for ethanol production to evaluate its feasibility compared with industrial product. The test on eight added ingredients, namely (NH 4) 2SO 4, NH 4Cl, yeast extract, soybean powder, corn powder, MgSO 4, KH 2PO 4 and CaCl 2, demonstrated that only CaCl 2 was the crucial factor during fermentation. The maximum glucoamylase 3404.44 U/ml was obtained at the addition 0.2% of CaCl 2. Ethanol production by enzymes produced from distillery waste was only about 2 g/L less than that by industrial product. This proves that the glucoamylase produced in this study could be used to take the place of industrial product. This method saves the cost of enzymes and decreases the pollution caused by distillery waste from ethanol production.

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350°C were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260°C. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260°C, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260°C. Heavy metals of Pb and Cd are almost vaporized above 1000°C. Cr is not volatile and its binding efficiency can reach 100% below 1000°C. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.