庞庄煤矿煤矸石淋溶液对周边水体影响分析

为研究庞庄煤矿张小楼煤矸石堆场淋溶液对其场地和周边地表水、地下水水质影响情况,围绕煤矸石堆场及周边采集13组水样做分析比对。结果表明,煤矸石堆场淋溶液对周边地表水体形成普遍污染,且污染物浓度随着污染距离增加逐步降低,一般化学污染指标主要包括溶解性总固体、硫酸盐、铁、锰、氨氮等,毒理学污染指标包括亚硝酸盐、氟化物、砷,超标倍率约为0.02~5.36。受距离及成井深度等因素影响,地下水体未遭受淋溶液明显的污染和影响。     

SPE-HPLC法测定固体废物浸出液中苯酚类物质

选择Agilent Bond Elut Plexa作为固相萃取柱,结合高效液相色谱测定固体废物浸出液中12种苯酚类化合物,通过试验优化条件,使目标物在0.100 mg/L~10.0 mg/L范围内线性良好,方法检出限在0.004μg/L~0.068μg/L之间,3个质量浓度水平加标回收率为78.0%~105%,测定6次结果的RSD为0.7%~5.0%。将该方法用于测定江苏省某工业园区污水处理企业5个废水处理污泥样品,结果 2,4,6-三氯苯酚和2,4-二硝基苯酚检出。     

Solidification/stabilisation of electric arc furnace waste using low grade MgO

This study aims to evaluate the potential of low grade MgO (LGMgO) for the stabilisation/solidification (S/S) of heavy metals in steel electric arc furnace wastes. Relevant characteristics such as setting time, unconfined compressive strength (UCS) and leaching behaviour assessed by acid neutralisation capacity (ANC), monolithic and granular leaching tests were examined in light of the UK landfill Waste Acceptance Criteria (WAC) for disposal. The results demonstrated that all studied mix designs with Portland cement type 1 (CEM1) and LGMgO, CEM1-LGMgO 1:2 and 1:4 at 40% and 70% waste addition met the WAC requirements by means of UCS, initial and final setting times and consistence. Most of the ANC results met the WAC limits where the threshold pH values without acid additions were stable and between 11.9 and 12.2 at 28 d.Granular leaching results indicate fixation of most of the metals at all mix ratios. An optimum ratio was obtained at CEM1-LGMgO 1:4 at 40% waste additions where none of the metals leaching exceeded the WAC limits and hence may be considered for landfill disposal.The monolithic leaching test results showed that LGMgO performed satisfactorily with respect to S/S of Zn, as the metal component present at the highest concentration level in the waste exhibited very little leaching and passed the leaching test requirement at all mix ratios studied. However, its performance with respect to Pb, Cd and Cr was less effective in reducing their leaching suggesting a higher cumulative rate under those leaching regimes.     

Impacts of pH and ammonia on the leaching of Cu(II) and Cd(II) from coal fly ash

Many coal-fired power plants are implementing ammonia-based technologies to reduce NO(x) emissions. Excess ammonia in the flue gas often deposits on the coal fly ash. Ammonia can form complexes with many heavy metals and change the leaching characteristics of these metals. This research tends to develop a fundamental understanding of the ammonia impact on the leaching of some heavy metals, exemplified by Cu(II) and Cd(II), under different pH conditions. Batch results indicated that the adsorption is the main mechanism controlling Cu(II) and Cd(II) leaching, and high concentrations of ammonia (>5,000 mg/l) can increase the release of Cu(II) and Cd(II) in the alkaline pH range. Based on the chemical reactions among fly ash, ammonia, and heavy metal ion, a mathematical model was developed to quantify effects of pH and ammonia on metal adsorption. The adsorption constants (logK) of Cu(2+), Cu(OH)(+), Cu(OH)(2), and Cu(NH(3))(m)(2+) for the fly ash under investigation were respectively 6.0, 7.7, 9.6, and 2.9. For Cd(II), these constants were respectively 4.3, 6.9, 8.8, and 2.6. Metal speciation calculations indicated that the formation of less adsorbable metal-ammonia complexes decreased metal adsorption, therefore enhanced metal leaching.     

浸出毒性鉴别重金属分析中存在的问题

浸出毒性鉴别是判定危险废物的依据之一,在固体废物管理中具有极重要的意义。但实际浸出毒性鉴别分析工作尚属于起步阶段,还存在诸多问题和难点,需要从各方面加强固体废物浸出毒性鉴别技术方面的研究,不断完善鉴别能力,使浸出毒性鉴别结果更加准确可靠。     

Effects of using arsenic–iron sludge wastes in brick making

The arsenic–iron sludge generated in most of the treatment systems around the world is discharged into the nearest watercourse, which leads to accumulative rise of arsenic and iron concentrations in water. In this study, attempts were made to use the arsenic–iron sludge in making bricks and to analyze the corresponding effects on brick properties. The water treatment plant sludge is extremely close to brick clay in chemical composition. So, the sludge could be a potential substitute for brick clay. This study involved the addition of sludge with ratios 3%, 6%, 9% and 12% of the total weight of sludge–clay mixture. The physical and chemical properties of the produced bricks were then determined and evaluated and compared to control brick made entirely from clay. Results of different tests indicated that the sludge proportion and firing temperature were the two key factors in determining the quality of bricks. The compressive strength of 3%, 6%, 9% and 12% sludge containing brick samples were found to be 14.1 MPa, 15.1 MPa, 9.4 MPa and 7.1 MPa, respectively. These results indicate that the compressive strength of prepared bricks initially increased and then decreased with the increase of sludge proportion. Leaching characteristics of burnt bricks were determined with the variation of pH at a constant temperature. The optimum amount of sludge that could be mixed with clay to produce good bonding of clay–sludge bricks was found to be 6% (safely maximum) by weight.     

Copper stabilization in beneficial use of waterworks sludge and copper-laden electroplating sludge for ceramic materials

A promising strategy for effectively incorporating metal-containing waste materials into a variety of ceramic products was devised in this study. Elemental analysis confirmed that copper was the predominant metal component in the collected electroplating sludge, and aluminum was the predominant constituent of waterworks sludge collected in Hong Kong. The use of waterworks sludge as an aluminum-rich precursor material to facilitate copper stabilization under thermal conditions provides a promising waste-to-resource strategy. When sintering the mixture of copper sludge and the 900 °C calcined waterworks sludge, the CuAl₂O₄ spinel phase was first detected at 650 °C and became the predominant product phase at temperatures higher than 850 °C. Quantification of the XRD pattern using the Rietveld refinement method revealed that the weight of the CuAl₂O₄ spinel phase reached over 50% at 850 °C. The strong signals of the CuAl₂O₄ phase continued until the temperature reached 1150 °C, and further sintering initiated the generation of the other copper-hosting phases (CuAlO₂, Cu₂O, and CuO). The copper stabilization effect was evaluated by the copper leachability of the CuAl₂O₄ and CuO via the prolonged leaching experiments at a pH value of 4.9. The leaching results showed that the CuAl₂O₄ phase was superior to the CuAlO₂ and CuO phases for immobilizing hazardous copper over longer leaching periods. The findings clearly indicate that spinel formation is the most crucial metal stabilization mechanism when sintering multiphase copper sludge with aluminum-rich waterworks sludge, and suggest a promising and reliable technique for reusing both types of sludge waste for ceramic materials.     

Supercritical water oxidation of tannery sludge: Stabilization of chromium and destruction of organics

The supercritical water oxidation (SCWO) of industrial tannery sludge was investigated to understand the simultaneous destruction of organic pollutants and recovery of high content chromium. Experiments were performed in a batch reactor at temperatures of 350–500 °C, reaction time of 150–300 s and different oxygen ratios, to exhibit the effect of operation conditions. Results showed that removal efficiency of chemical oxygen demand (COD) increased with higher temperature, larger oxidant amount and reaction time; a maximum value of 96% was obtained. Meanwhile, destruction yield was much higher under supercritical conditions than that in subcritical water. In addition, removal efficiency of Cr from sludge reached more than 98% under all conditions; higher temperature played a positive role. Further, leaching toxicity tests of heavy metals in solid products were conducted based on toxicity characteristic leaching procedure. All heavy metals except nickel showed a greatly reduced leaching toxicity through their stabilization. The chromium oxide recovered in ash was amorphous below 550 °C, so that the structure of Cr could not be identified by X-ray diffraction pattern. Special attention should be paid on nickel as its leaching toxicity increased due to the corrosion of reactor surface under severe reaction conditions.     

Fates and transport of PPCPs in soil receiving reclaimed water irrigation

Fates and transport of 9 commonly found PPCPs of the reclaimed water were simulated based on the HYDRUS-1D software that was validated with data generated from field experiments. Under the default scenario in which the model parameters and input data represented the typical conditions of turf grass irrigation in southern California, the adsorption, degradation, and volatilization of clofibric acid, ibuprofen, 4-tert-octylphenol, 4-n-nonylphenol, naproxen, triclosan, diclofenac sodium, bisphenol A and estrone in the receiving soils were tracked for 10 years. At the end, their accumulations in the 90 cm soil profile varied from less than 1 ng g⁻¹ to about 140 ng g⁻¹ and their concentrations in the drainage water in the 90 cm soil depth varied from nil to μg L⁻¹ levels. The adsorption and microbial degradation processes interacted to contain the PPCPs entirely within surface 40 cm of the soil profiles. Leaching and volatilization were not significant processes governing the PPCPs in the soils. The extent of accumulations in the soils did not appear to produce undue ecological risks to the soil biota. PPCPs did not represent any potential environmental harm in reclaimed water irrigation.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.