[Analysis of pollution characteristics of solid waste incinerator fly ash in Zhejiang province].

Pollutants characteristics, especially in components and contents of heavy metals and PCDD/Fs, were chemical analyzed and toxicological evaluated in fly ash from 6 typical kinds of solid waste incinerators in Zhejiang province. The results indicated that the main elements in fly ash were Si, Ca, Al, Fe, K, Na and Cl. Among all kinds of heavy metals, the Zn content was the highest one, whose average was up to 9 458 mg/kg. Meanwhile, the Cd, Zn, Cu,Cr,Ni, Pb and As contents in the fly ash samples were 642, 127, 22, 18,15, 10 and 2-fold of those in polluted soil, respectively. The leaching ratios of heavy metals in fly ash concluded according to the HJ/T 299-2007 Procedure were lower than its limitation. However, the leaching ratios from NB and LS sample concluded according to the Toxicity Characteristic Leaching Procedure (TCLP) exceeded its limitation. The TEQ of PCDD/Fs from all samples were lower than the limitation in GB 5085.6-2007, while higher than the soil-limitation in Canadian, New Zealand and Sweden, with 105, 59, 401, 369 and 5-fold in the sample HZ, WZ, NB, TZ and HUZ, respectively. It could be concluded that the components and contents of the pollutants were various from different fly ashes. The components of heavy metals were mainly affected by the type of solid wastes. And the technology of the incinerator played important role in the pollution characteristics in fly ash. Thus, it is of significant meaning to study the particulate pollution characteristics of a certain fly ash before disposal or reuse for the purpose of adequate risk assessment and management.

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.