Dong-g Shen

An innovative combined on-site process for the remote rural solid waste treatment--a pilot scale case study in China.

The aim of this study was to find a feasible method for the treatment of solid waste generated in the remote rural, where the transportation costs are prohibitive and the resources to construct and maintain conventional treatment plants are not available. This process, consisted of two types of simulated bioreactor landfill (one was recirculated bioreactor landfill, and the other was comprised of fresh and aged refuse reactor) and a soil infiltration system, was operated in ambient temperature for 180 days all together. After treated by the system of fresh and aged refuse reactor, the refuse and leachate reached a strongly degraded and stable state. The remaining leachate can be treated by the soil infiltration system, and 87.5 ± 2.1%, 98.6 ± 1.0% and 95.7 ± 1.7% were achieved by 60 cm soil depths for organic matter, ammonium nitrogen and total nitrogen removal, respectively.

Effect of weathering treatment on the fractionation and leaching behavior of copper in municipal solid waste incinerator bottom ash

This work describes the effect of weathering of fresh quenched municipal solid waste incinerator (MSWI) bottom ash on the fractionation and leaching behavior of Cu. A sequential extraction procedure was used to characterize the fractionation of Cu in the fresh and weathered MSWI bottom ash samples. It showed that the organic matter bound fraction of Cu decreased drastically from 69% to 37% during the weathering treatment, while the residual fraction, Fe-Mn oxides bound fraction, carbonate bound fraction and exchangeable fraction increased from 24% to 54%, 3% to 4%, 2% to 3% and 2% to 3%, respectively. Furthermore, two standard leaching procedures, synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP), were carried out on the fresh and weathered samples. The leaching of Cu was attenuated with the process of weathering treatment in the SPLP procedure, but was enhanced in the TCLP procedure. The results suggested that the weathering treatment could change the fractionation and leaching behavior of Cu in MSWI bottom ash. Further research is required to correlate weathering of ash and mobility of Cu.

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province, China: chemical and bio-analytical characterization

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1–1175, 1.1–57, 61.6–620, 0.4–223, 16.6–4380, 1.2–94.7, and 0.03–1.4xa0μgxa0g−1xa0dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939xa0μgxa0g−1xa0dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177xa0μgxa0g−1xa0dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC50 values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.

Effect of liquid-to-solid ratio on semi-solid Fenton process in hazardous solid waste detoxication

The liquid-to-solid ratio (L/S) of semi-solid Fenton process (SSFP) designated for hazardous solid waste detoxication was investigated. The removal and minimization effects of o-nitroaniline (ONA) in simulate solid waste residue (SSWR) from organic arsenic industry was evaluated by total organic carbon (TOC) and ONA removal efficiency, respectively. Initially, Box-Behnken design (BBD) and response surface methodology (RSM) were used to optimize the key factors of SSFP. Results showed that the removal rates of TOC and ONA decreased as L/S increased. Subsequently, four target initial ONA concentrations including 100 mg kg(-1), 1 g kg(-1), 10 g kg(-1), and 100 gk g(-1) on a dry basis were evaluated for the effect of L/S. A significant cubic empirical model between the initial ONA concentration and L/S was successfully developed to predict the optimal L/S for given initial ONA concentration for SSFP. Moreover, an optimized operation strategy of multi-SSFP for different cases was determined based on the residual target pollutant concentration and the corresponding environmental conditions. It showed that the total L/S of multi-SSFP in all tested scenarios was no greater than 3.8, which is lower than the conventional slurry systems (L/S ≥ 5). The multi-SSFP is environment-friendly when it used for detoxication of hazardous solid waste contaminated by ONA and provides a potential method for the detoxication of hazardous solid waste contaminated by organics.

Leaching behavior of iron from simulated landfills with different operational modes.

The aim of the present study was to investigate the leaching behavior of iron from simulated landfills with different operation modes, with an emphasis on the variation of iron in different oxidation state, ferrous Fe(II) and ferric Fe(III) percentage and the distribution of iron content in different landfill leachate fractions. The leaching behavior and accumulated amounts of iron leached out by leachate from conventional landfill (CL) and leachate recirculated landfill (RL) exhibited decidedly different trends except for the initial 28 days. In addition, the percentage of iron leached from CL and RL accounted 1.00% and 0.14% for the total amount in landfills, respectively. No correlations between iron and selected characteristics in leachate were found were observed in the two simulated landfills. Significant positive correlations between particulate bound iron and Fe(III) were found in the leachates from RL (R(2)=0.748) and CL (R(2)=0.833).

Shortcut biological nitrogen removal in continuous-flow anoxic/aerobic process for treating low-strength ammonium wastewater

AbstractThe aim of this study was to achieve shortcut biological nitrogen removal (BNR) in a laboratory-scale continuous-flow anoxic/aerobic process. A BNR reactor and a hybrid biofilm nitrogen removal (HBNR) reactor fed with low-strength ammonium wastewater were employed. The pathway of nitrogen conversion in both reactors was also evaluated. Results showed that effective biological nitrogen removal could be reliably achieved in both reactors, with over 69% total nitrogen (TN) and 95% removal efficiencies. HBNR improved the TN removal efficiency by over 15% relative to conventional BNR. Based on nitrogen mass balance, the fates of nitrogen in the HBNR and BNR differed, with most nitrogen removal occurring by SBNR via nitrite in the anoxic tank of the BNR and by simultaneous nitrification–denitrification via nitrite in the aerobic tank of the HBNR. The specific oxygen utilization rate test and real-time quantitative polymerase chain reaction indicated that ammonia-oxidizing bacteria were dominant in activ...