Bioremediation of aerobically treated distillery sludge mixed with cow dung by using an epigeic earthworm Eisenia fetida

The potential of the epigeic earthworm Eisenia fetida to stabilize sludge␣(generated from a distillation unit of the sugar industry) mixed with cow dung, in different proportions i.e. 20% (T₁), 40% (T₂), 60% (T₃) and 80% (T₄) has been studied under laboratory conditions for 90 days. The␣ready vermicompost was evaluated for its’ different physico-chemical parameters using standard methods. At the end of experiment, all vermibeds expressed a significant decrease in pH (7.8–19.2%) organic C (8.5–25.8%) content, and an increase in total N (130.4–170.7%), available P (22.2–120.8%), exchangeable K (104.9–159.5%), exchangeable Ca (49.1–118.1%), and exchangeable Mg (13.6–51.2%) content. Overall, earthworms could maximize decomposition and mineralization efficiency in bedding with lower proportions of distillery sludge. DTPA extractable metal reduction in substrate was recorded between the ranges of 12.5–38.8% for Zn, 5.9–30.4% for Fe, 4.7–38.2% for Mn and 4.5–42.1% for Cu. Maximum values for the mean individual live weight (809.69 ± 20.09 mg) and maximum individual growth rate (mg wt. worm⁻¹ day⁻¹) (5.81 ± 0.18) of earthworms was noted in T₁ treatment, whereas cocoon numbers (69.0 ± 7.94) and individual reproduction rate (cocoon worm⁻¹ day⁻¹) (0.046 ± 0.002) was highest in T₂ treatment. Earthworm mortality tended to increase with increasing proportion of distillery sludge, and maximum mortality in E. fetida was recorded for the T₄ (45.0 ± 5.0) treatment. Results indicate that vermicomposting might be useful for managing the energy and nutrient rich distillery sludge on a low-input basis. Products of this process can be used for sustainable land restoration practices. The feasibility of worms to mitigate the toxicity of metals also reduces the possibility of soil contamination, which has been reported in earlier studies during direct field application of industrial wastes.     

Sterilization affects soil organic matter chemistry and bioaccumulation of spiked p,p′-DDE and anthracene by earthworms

Laboratory experiments were conducted to assess the effects of soil sterilization on the bioavailability of spiked p,p′-DDE and anthracene to the earthworms Eisenia fetida and Lumbricus terrestris. Physical and chemical changes to soil organic matter (SOM) induced by sterilization were also studied. Uptake of both compounds added after soil was autoclaved or gamma irradiated increased for E. fetida. Sterilization had no effect on bioaccumulation of p,p′-DDE by L. terrestris, and anthracene uptake increased only in gamma-irradiated soils. Analyses by FT-IR and DSC indicate sterilization alters SOM chemistry and may reduce pollutant sorption. Chemical changes to SOM were tentatively linked to changes in bioaccumulation, although the effects were compound and species specific. Artifacts produced by sterilization could lead to inaccurate risk assessments of contaminated sites if assumptions derived from studies carried out in sterilized soil are used. Ultimately, knowledge of SOM chemistry could aid predictions of bioaccumulation of organic pollutants.     

H NMR metabolomics of earthworm exposure to sub-lethal concentrations of phenanthrene in soil

¹H NMR metabolomics was used to monitor earthworm responses to sub-lethal (50-1500 mg/kg) phenanthrene exposure in soil. Total phenanthrene was analyzed via soxhlet extraction, bioavailable phenanthrene was estimated by hydroxypropyl-β-cyclodextrin (HPCD) and 1-butanol extractions and sorption to soil was assessed by batch equilibration. Bioavailable phenanthrene (HPCD-extracted) comprised ∼65-97% of total phenanthrene added to the soil. Principal component analysis (PCA) showed differences in responses between exposed earthworms and controls after 48 h exposure. The metabolites that varied with exposure included amino acids (isoleucine, alanine and glutamine) and maltose. PLS models indicated that earthworm response is positively correlated to both total phenanthrene concentration and bioavailable (HPCD-extracted) phenanthrene in a freshly spiked, unaged soil. These results show that metabolomics is a powerful, direct technique that may be used to monitor contaminant bioavailability and toxicity of sub-lethal concentrations of contaminants in the environment. These initial findings warrant further metabolomic studies with aged contaminated soils.     

绿色生态滤池处理城镇污水的中试研究

绿色生态滤池是一种利用由微生物和蚯蚓为代表的微型动物共同组成的人工生态系统对城镇污水中的污染物质进行降解处理的新型环保技术。该生态滤池由布水区、蚯蚓滤床和排水区三部分组成，集物理过滤、吸附、好氧和厌氧生物处理以及污泥堆肥处理等诸多处理功能于一身。本研究中生态滤池处理城镇污水的ＣＯＤｃｒ去除率达８３％～８８％，ＢＯＤ５去除率达９１％～９６％，ＳＳ去除率达８５％～９２％，氨氮去除率达５５％～６５％。具     

城镇污水处理绿色技术及其进展

研究能耗、物耗和二次污染最少化的城镇污水处理绿色工艺已成为我国城镇污水处理技术研究的重要方向。国内新研究开发成功的厌氧水解－高负荷生物滤池和蚯蚓生态滤池就是其中突出的代表。通过处理工艺、环境影响和技术经济指标诸方面的比较,可以看出,厌氧水解－高负荷生物滤池和蚯蚓生态滤池这种绿色技术的污水处理效果达到或超过了活性污泥法,既大幅度减少了剩余污泥产量和其他二次污染物,又可节约20％－45％的工程造价,50％－65％的运行费用,操作管理简单方便,对我国中小城镇具有巨大的应用潜力。     

蚯蚓处理重金属的毒理学研究启示

介绍了蚯蚓的生态毒理学研究方法以及重金属与蚯蚓的相互影响作用,并通过对早期的剩余污泥中重金属的去除方法作对比,提出了利用蚯蚓处理剩余活性污泥中重金属的技术,为剩余污泥的资源利用化提供了新的途径。     

蚯蚓生物反应器污泥减量与稳定效果试验研究

蚯蚓生物反应器以蚯矧等微型动物和各种微生物为主形成生物降解系统.城镇污水经生物预处理后,经该反应器过滤,水质得到澄清和进一步改善,而水中含有的生物膜污泥则被滤床截留.通过蚯蚓的吸收、消化和分解转化为蚯蚓排泄物(蚓粪).中试运行结果表明,当蚯蚓生物反应器水力负荷为5.3～6.6 m3/(m2·d)时,在满足污水处理效果条件下,蚯蚓生物反应器对生物膜污泥挥发性悬浮固体(VSS)降解率为86.67%～96.20%.所产生的蚓粪VSS:SS为29.97%～31.20%,有机物降解率超过了厌氧消化与好氧消化处理污泥的效果.减量化和稳定化效果十分明显.该系统排出的蚓粪含有丰富的肥分,可用作农肥与土壤改良剂.     

Ecotoxicological responses of the earthworm Eisenia fetida exposed to soil contaminated with HHCB

Although polycyclic musks have been shown to cause lethal and sub-lethal effects on organisms, their biochemical toxicity to earthworms is not well understood. In the current study, we investigated the responses of antioxidant systems and lipid peroxidation after exposing Eisenia fetida to soil contaminated with 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-γ-2-benzopyran (HHCB). Significant increase in lipid peroxidation level was observed on day 14 at two high concentrations, 50 and 100 mg kg⁻¹. Among antioxidant enzymes, the primary response to chronic HHCB exposure can be attributed to superoxide dismutase (SOD) and catalase (CAT). Of the two enzymes, SOD exhibited more sensitive response to HHCB stress. In addition, these two enzymes could have a combined effect on fighting damage by reactive oxygen species, evidenced by a marked relationship between lipid peroxidation and enzyme activity. On the other hand, dose-dependent inhibition of peroxidase (POD) activity has been observed throughout the test. The results suggest that the variations in investigated parameters of E. fetida could be used as responsive biomarkers for oxidative stress caused by HHCB in a soil environment.