Smith S R
Department of Civil and Environmental Engineering, Imperial College London, , London SW7 2AZ, UK.
Philos Trans A Math Phys Eng Sci. 2009 Oct 13;367(1904):4005-41. doi: 10.1098/rsta.2009.0154.
Organic chemicals discharged in urban wastewater from industrial and domestic sources, or those entering through atmospheric deposition onto paved areas via surface run-off, are predominantly lipophilic in nature and therefore become concentrated in sewage sludge, with potential implications for the agricultural use of sludge as a soil improver. Biodegradation occurs to varying degrees during wastewater and sludge treatment processes. However, residues will probably still be present in the resulting sludge and can vary from trace values of several micrograms per kilogram up to approximately 1 per cent in the dry solids for certain bulk chemicals, such as linear alkylbenzene sulphonate, which is widely used as a surfactant in detergent formulations. However, the review of the scientific literature on the potential environmental and health impacts of organic contaminants (OCs) in sludge indicates that the presence of a compound in sludge, or of seemingly large amounts of certain compounds used in bulk volumes domestically and by industry, does not necessarily constitute a hazard when the material is recycled to farmland. Furthermore, the chemical quality of sludge is continually improving and concentrations of potentially harmful and persistent organic compounds have declined to background values. Thus, recycling sewage sludge on farmland is not constrained by concentrations of OCs found in contemporary sewage sludges. A number of issues, while unlikely to be significant for agricultural utilization, require further investigation and include: (i) the impacts of chlorinated paraffins on the food chain and human health, (ii) the risk assessment of the plasticizer di(2-ethylhexyl)phthalate, a bulk chemical present in large amounts in sludge, (iii) the microbiological risk assessment of antibiotic-resistant micro-organisms in sewage sludge and sludge-amended agricultural soil, and (iv) the potential significance of personal-care products (e.g. triclosan), pharmaceuticals and endocrine-disrupting compounds in sludge on soil quality and human health.
从工业和家庭来源排放到城市废水中的有机化学品，或通过大气沉降经地表径流进入铺砌区域的有机化学品，本质上主要是亲脂性的，因此会在污水污泥中浓缩，这可能会对污泥作为土壤改良剂的农业用途产生影响。在废水和污泥处理过程中，生物降解会在不同程度上发生。然而，最终的污泥中可能仍会存在残留物，某些大宗化学品，如广泛用作洗涤剂配方表面活性剂的直链烷基苯磺酸盐，其残留量在干固体中可能从每千克几微克的痕量值到约1%不等。然而，对有关污泥中有机污染物（OCs）潜在环境和健康影响的科学文献的综述表明，当污泥被回用于农田时，污泥中存在某种化合物，或国内和工业大量使用的某些化合物看似含量很高，并不一定构成危害。此外，污泥的化学质量在不断改善，潜在有害和持久性有机化合物的浓度已降至背景值。因此，农田回用污水污泥不受当代污水污泥中OCs浓度的限制。有一些问题虽然对农业利用可能影响不大，但仍需要进一步研究，包括：（i）氯化石蜡对食物链和人类健康的影响；（ii）污泥中大量存在的增塑剂邻苯二甲酸二（2-乙基己基）酯的风险评估；（iii）污水污泥和施用污泥的农业土壤中抗生素抗性微生物的微生物风险评估；以及（iv）污泥中的个人护理产品（如三氯生）、药物和内分泌干扰化合物对土壤质量和人类健康的潜在影响。
