Use of sewage sludge, a biological residue produced from sewage treatment processes in agriculture is an alternative disposal technique of waste. To study the usefulness of sewage sludge amendment for palak (Beta vulgaris var. Allgreen H-1), a leafy vegetable and consequent heavy metal contamination, a pot experiment was conducted by mixing sewage sludge at 20% and 40% (w/w) amendment ratios to the agricultural soil. Soil pH decreased whereas electrical conductance, organic carbon, total N, available P and exchangeable Na, K and Ca increased in soil amended with sewage sludge in comparison to unamended soil. Sewage sludge amendment led to significant increase in Pb, Cr, Cd, Cu, Zn and Ni concentrations of soil. Cd concentration in soil was found above the Indian permissible limit in soil at both the amendment ratios.
The increased concentration of heavy metals in soil due to sewage sludge amendment led to increases in heavy metal uptake and shoot and root concentrations of Ni, Cd, Cu, Cr, Pb and Zn in plants as compared to those grown on unamended soil. Accumulation was more in roots than shoots for most of the heavy metals. Concentrations of Cd, Ni and Zn were more than the permissible limits of Indian standard in the edible portion of palak grown on different sewage sludge amendments ratios. Sewage sludge amendment in soil decreased root length, leaf area and root biomass of palak at both the amendment ratios, whereas shoot biomass and yield decreased significantly at 40% sludge amendment. Rate of photosynthesis, stomatal conductance and chlorophyll content decreased whereas lipid peroxidation, peroxidase activity and protein and proline contents, increased in plants grown in sewage sludge-amended soil as compared to those grown in unamended soil.
The study clearly shows that increase in heavy metal concentration in foliage of plants grown in sewage sludge-amended soil caused unfavorable changes in physiological and biochemical characteristics of plants leading to reductions in morphological characteristics, biomass accumulation and yield. The study concludes that sewage sludge amendment in soil for growing palak may not be a good option due to risk of contamination of Cd, Ni and Zn and also due to lowering of yield at higher mixing ratio. 相似文献
Combustion of urban sewage sludge together with coal in existing infrastructures may be a sustainable management option energetically interesting for these materials, usually considered wastes. Thermogravimetric analysis was used to study the combustion of a semianthracite coal and the modifications undergone when adding a small percentage (2%, 5%, 10%) of sewage sludge. Both Differential Scanning Calorimetric analysis and Differential Thermogravimetry burning profiles showed differences between coal and sewage sludge combustion. However, the effects of adding a percentage of sewage sludge equal or smaller than 10% was hardly noticeable in terms of heat release and weight loss during the coal combustion. This was further proved by non-isothermal kinetic analysis, which was used to evaluate the Arrhenius activation energy corresponding to the co-combustion of the blends. This work shows that thermogravimetric analysis may be used as an easy rapid tool to asses the co-combustion of sewage sludge together with coal. 相似文献
The present work focuses on the fate of two cancerostatic platinum compounds (CPC), cisplatin and carboplatin, as well as of two inorganic platinum compounds, [PtCl4]2− and [PtCl6]2− in biological wastewater treatment. Laboratory experiments modelling adsorption of these compounds onto activated sludge showed promising specific adsorption coefficients KD and KOC and Freundlich adsorption isotherms. However, the adsorption properties of the investigated substances were differing significantly. Adsorption decreased following the order cisplatin > [PtCl6]2− > [PtCl4]2− > carboplatin. Log KD-values were ranging from 2.5 to 4.3 , log KOC from 3.0 to 4.7.
A pilot membrane bioreactor system (MBR) was installed in a hospital in Vienna and fed with wastewater from the oncologic in-patient treatment ward to investigate CPC-adsorption in a sewage treatment plant. During three monitoring periods Pt-concentrations were measured in the influent (3–250 μg l−1 Pt) and the effluent (2–150 μg l−1 Pt) of the treatment plant using ICP-MS. The monitoring periods (duration 30 d) revealed elimination efficiencies between 51% and 63% based on averaged weekly input–output budgets. The derived log KD-values and log KOC-values ranged from 2.4 to 4.8 and from 2.8 to 5.3, respectively. Species analysis using HPLC-ICP-MS proofed that mainly carboplatin was present as intact drug in the influent and – due to low log KD – in the effluent of the MBR. 相似文献
Samples of effluents, sludge, pulp, final products (paper) and soil were collected from the identified pulp and paper mills
in India. The samples were analysed for 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD) and other dioxin congeners and
precursors. Pulp and paper mills using chlorine for the bleaching process showed the presence of 2,3,7,8-TCDD in effluent
samples. In the effluent and pulp samples from mills where chlorine dioxide was used as a bleaching agent, the 2,3,7,8-TCDD
congener ranged from below the detection limit 0.05 to 0.12 ngL−1/ngg−1. The relative standard deviation of reproducibility and the percent recovery of 2,3,7,8-TCDD were 2.07 and 82.4% in pulp
and 2.8 and 92% in effluent, respectively. The 1,3,6,8-TCDD was the only other major dioxin congener found in the treated
and untreated effluent and sludge samples. However, dichlorobenzene, trichlorophenyl, and hexachlorobiphenyl were detected
in all samples. The formation of dioxins can be minimised by replacing chlorine with chlorine dioxide in bleaching processes
in pulp and paper mills. 相似文献
Natural steroidal estrogens, such as 17 β-estradiol (E2), as well as antimicrobials such as doxycycline and norfloxacin, are excreted by humans and hence detected in sewage sludge and biosolid. The disposal of human waste products on agricultural land results in estrogens and antibiotics being detected as mixtures in soils. The objective of this study was to examine microbial respiration and E2 mineralization in sewage sludge, biosolid, and soil in the presence and the absence of doxycycline and norfloxacin. The antimicrobials were applied to the media either alone or in combination at total rates of 4 and 40 mg kg?1, with the 4 mg kg?1 rate being an environmentally relevant concentration. The calculated time that half of the applied E2 was mineralized ranged from 294 to 418 days in sewage sludge, from 721 to 869 days in soil, and from 2,258 to 14,146 days in biosolid. E2 mineralization followed first-order and the presence of antimicrobials had no significant effect on mineralization half-lives, except for some antimicrobial applications to the human waste products. At 189 day, total E2 mineralization was significantly greater in sewage sludge (38 ±0.7%) > soil (23 ±0.7%) > biosolid (3 ±0.7%), while total respiration was significantly greater in biosolid (1,258 mg CO2) > sewage sludge (253 mg CO2) ≥ soil (131 mg CO2). Strong sorption of E2 to the organic fraction in biosolid may have resulted in reduced E2 mineralization despite the high microbial activity in this media. Total E2 mineralization at 189 day was not significantly influenced by the presence of doxycycline and/or norfloxacin in the media. Antimicrobial additions also did not significantly influence total respiration in media, except that total CO2 respiration at 189 day was significantly greater for biosolid with 40 mg kg?1 doxycycline added, relative to biosolid without antimicrobials. We conclude that it is unlikely for doxycycline and norfloxacin, or their mixtures, to have a significant effect on E2 mineralization in human waste products and soil. However, the potential for E2 to be persistent in biosolids, with and without the presence of antimicrobials, is posing a challenge for biosolid disposal to agricultural lands. 相似文献