城市污泥堆肥对栽培基质保水能力和有效关效养分的影响

盆栽试验表明,城市污泥堆肥不仅可以明显提高栽培基质的有效氮、磷含量,而且可以增强栽培基质的保水性能和植物的抗旱能力,但是栽培基质的萎焉点也随着其用量的增加而增高,因此,从保证植物水分供应的角度考虑,虽然可以大量地使用城市污泥堆肥,但是其用量并不是越多越好;当用量超过75％时,继续增加城市污泥堆肥的比例,则植物的吸水能力反而会略有下降,从养分供应和保水性能等角度综合考虑,采用经过堆肥处理的城市污泥作为植物栽培基质,是城市污泥资源化和无害化的可行途径。     

城市污泥堆肥用作草皮基质对草坪草生长的影响

研究了城市污泥堆肥生产草坪基质的应用效果。试验结果表明,城市污泥堆肥基质能明显提高黑麦草的地上和地下生物量和叶绿素含量,与不施化肥和施用化学的对照相比,城市污泥堆肥可以增加土壤有效态氮、磷含量,促进植物叶片对氮的吸收,提高草坪的质量。用经过无害化处理的城市污泥生产草坪基质,既可以解决城市污泥的出路,又可以降低草坪的生产成本,是一条经济可行的途径。     

鼓风对城市污泥好氧堆肥温度变化的影响

采用强制通风静态垛和温度反馈自动测控堆肥工艺,研究了鼓风过程对城市污泥好氧堆肥温度的影响。当城市污泥和调理剂比例为1：1时（体积比）,处于鼓风口远端（风向远点）各个层次的堆体温度基本上不会随鼓风过程而变化,处于鼓风方向中部（风向中点）、鼓风口近端（风向近点）的堆体,其中层、上层的温度将会下降,平均下降速度分别为0.05℃/min、0.04℃/min,但是温度下降的速率在整个鼓风过程中并不均匀,温度下降速度在0－10min较快,在10－40min较慢;当混合堆料中调理剂含量较低时（3：2）,堆体上层温度在鼓风过程中将会上升,上升速率约为0.022-0.05℃/min,中层温度下降,在鼓风开始阶段（0－10min）,下降速率较快,约为0.12℃/min,随后变化速率较小,约为0.01℃/min。对于不同调理剂比例的堆体,处于风向远点、中点的下层温度基本不受鼓风作用的影响;处于风向近点的堆体,其下层温度会随着鼓风过程而下降,平均下降速率约为0.025-0.03℃/min。     

构树的污泥适应性及养分和重金属吸收累积特征

构树是我国重要速生经济树种,具有适应性强、生物量大和重金属富集能力强等优点,而污泥中含有大量养分和重金属,在污泥中种植构树有望同时实现污泥生态修复和构树资源生产。本研究通过盆栽试验,分析在对照(赤红壤)、50%污泥(污泥、赤红壤混合基质,重量比各50%)和100%污泥基质中构树生长及不同部位(根、茎、叶)养分和重金属吸收累积特征,并通过主成分分析和隶属度函数对吸收累积能力进行综合评价。结果表明: 构树在50%和100%污泥中均可正常生长且株高、生物量显著高于对照,在100%污泥中长势最好,质量指数(1.02)分别是对照和50%污泥处理的4.3和2.4倍。50%和100%污泥处理构树各部位N含量和茎P含量显著高于对照,100%污泥处理构树茎、叶K含量显著低于对照。构树对Cu、Zn、Pb、Cd、Ni的吸收部位以根为主,根系重金属含量与污泥比例呈正相关,叶Pb、Cd含量符合《饲料卫生标准》(GB 13078—2017)。构树对Cd的吸收累积效果好于其他重金属元素。与对照相比,50%和100%污泥处理构树根部Zn、Pb、Cd滞留率显著提高(57.8%~85.8%),100%污泥处理构树根部Cu、Ni滞留率显著提高(67.5%和74.8%)。污泥处理全株养分和重金属累积量均显著大于对照,其中100%污泥处理显著大于50%污泥处理。与50%污泥处理相比,100%污泥处理构树各部位及全株养分和重金属累积量大幅提高。不同处理下构树污泥适应性和元素吸收累积的综合评价得分为100%污泥(0.848)>50%污泥(0.344)>对照(0.080)。构树对污泥具有良好的适应性,在纯污泥中能够正常生长并具有较强的吸收累积养分和重金属能力,可在修复污泥的同时进行构树资源生产。     

施用污泥对油菜根际养分和不同种类重金属的影响

根际是控制植物养分动态的重要因素,养分动态也影响着根际土壤环境。当土壤被污水污泥改良后,根际土壤中的养分和重金属性质也会发生变化。目前很少有人研究施用污泥的土壤中植物根系对根际重金属有效性和分布的影响。采用根垫—冰冻薄层切片法对施用污泥后土壤中油菜根际的养分和重金属分布情况进行研究,以期探明污泥改良土壤中根际重金属的活化特征。当土壤施用污泥后,根际土壤中DTPA提取态Zn,Cd,Ni,Mn,有效磷,有效钾和铵态氮被显著消耗,而根际土壤中DTPA提取态Cu没有明显的消耗或积累。当土壤中施用大量污泥时,根际土壤的pH值随着离根表面距离的增加而增加。无论土壤是否用污泥处理,油菜根际土壤中可交换态Cu都显著减少。当土壤被50%污泥改良时,在距离根表面0—2 mm处的油菜根际土壤中碳酸盐结合态,铁锰氧化物结合态,有机物结合态,残渣态的Cu和Zn都被消耗较多。污泥的施用对油菜的生长有促进作用。随着污泥施用量的增加,油菜地上部分Cu和Zn的含量没有显著变化。施用污泥量小于25%的土壤中,污泥没有增加重金属的可利用性和移动性。除了Cu,油菜根际土壤中DTPA提取态Zn,Cd,Ni的减少表明施用污泥的土壤中重金属的活化是非常有限的。     

污泥堆肥混合基质对香彩雀生长开花的影响及植物适应性评价

采用盆栽试验,研究了以城市污泥堆肥为主要原料的基质对观花植物香彩雀(Angelonia salicariifolia Humb.)生长和开花特性的影响,并采用熵权系数与TOPSIS集成评价法综合评价了不同基质对香彩雀的生长适应性。结果表明,经过60 d高温好氧堆制的污泥堆肥,以不同体积比与泥炭、河沙混配成的栽培基质容重和EC值比研究区的林地赤红壤低,pH值和养分含量更高。污泥堆肥混合基质栽培的香彩雀营养生长和生殖生长均优于土壤栽培,其中株高比后者增加29%~61%,分枝数增加27%~67%,鲜重增加17%~88%,干重增加4%~50%,开花时间提前2~16 d,花朵数增加49%~220%,花期延长8~22 d,花朵畸形率降低1%~5%,对氮、磷、钾的吸收能力显著提高。试验中各种污泥堆肥混合基质均适合香彩雀生长,熵权系数与TOPSIS集成评价结果显示,在所研究的污泥堆肥基质中,污泥堆肥:泥炭:河沙体积比为5∶3∶2的基质植物适应性最强,纯污泥堆肥植物适应性相对较差,但优于土壤。将污泥堆肥作为基质主要成分用于花卉生产,既可提高花卉质量,降低成本,又能消耗大量污泥,是城市污泥资源化处置和利用的重要方向。     

城市污泥农用对生态的影响

简述了城市污泥中有害物质对环境的影响,介绍了现行污泥处理工艺中存在的不足,对目前技术条件下采用污泥农用提出了质疑。     

填充料和通气对污泥堆肥过程的影响

试验研究了不同配比的以料和通气状况对污泥堆肥起始升温的影响。结果表明,填充料含是量高的配比升温速度明显比填充料含量低的配比快;高填充料配比的堆体（填充料占堆料的１／２～１／３）在超始升温阶段可以不进行氢气的供给;低填充料的配比和加入回流堆肥的配比（填充料占堆料的１／４～１／９）,由于堆体的孔隙少,则必须进行通气量的调节。     

城市污泥应用于边坡植被恢复对地表水环境的影响

将城市污泥应用于生态恢复因能避开粮食作物食物链而具有良好前景,但其对地表水环境影响仍不十分清楚.本文将城市污泥与建筑垃圾按1∶1体积比混合为生长基质,覆盖在模拟的煤矸石边坡上,播种8种乡土木本植物,对生长季植物生长情况以及坡面地表水和下渗水的电导率、p H、氮磷钾、重金属、多环芳烃等含量进行分析.结果表明:坡面植物生长良好,平均覆盖度达60%;地表水和下渗水的p H值近中性,变化不大,而电导率、氮磷钾、重金属和多环芳烃含量均较高,其中,氮、磷含量在整个生长季超过国家地表水环境质量Ⅴ类水质标准;7月重金属含量最高,其中,As含量只达地表水环境质量Ⅳ~Ⅴ类标准,其余重金属含量多达Ⅱ~Ⅳ标准;随着夏季雨水淋洗增加以及植物-土壤系统对化学物质的吸收、降解和固着作用,地表水和下渗水的电导率、氮磷钾、重金属和多环芳烃含量均显著下降,生长季后期重金属含量达到地表水环境质量Ⅱ~Ⅲ类标准,多环芳烃含量减少约一半.将城市污泥直接应用在煤矸石边坡生态恢复中有利于植物生长,植物-土壤系统使得生长基质中的有害物含量逐渐降低,对地表水环境的负影响主要表现为氮、磷的富营养化,但总体上其环境安全性可控.     

城市污泥农用对植物-土壤系统的影响

城市污泥的合理处置是目前资源与环境科学研究领域中的重要课题之一.城市污泥因富含大量的有机质和有效营养成分,对农业土壤肥力、土壤物理结构和农业生产均有一定的积极促进作用,使得污泥农用成为可能.但城市污泥中含有的重金属、有机污染物等有害物质尤其是重金属,成为污泥农用处置的瓶颈.为提高我国城市污泥的农业资源化利用效率和减少污染物造成的负面效应,本文就国内外施用城市污泥对植物-土壤互作系统的影响及过程进行了综述,为进一步提高污泥利用效率提供理论依据和科学指导.     

城市污泥复合肥的肥效及其对小麦重金属吸收的影响

通过盆栽和大田试验,初步探讨了污泥复合肥种植小麦的肥效及其对小麦重金属吸收的影响。试验结果表明,污泥复合肥对小麦的增产效果和土壤的增肥效果明显优于化肥,等同于市售复合肥,它能促进植株生长发育,提高小麦产量,对土壤速效养分的积累有明显的促进作用;污泥复合肥处理的小麦籽粒中重金属Cu、Zn、Pb、Cd的含量均在国家食品卫生标准范围内。     

底物种类和浓度对污泥重金属生物淋滤效果的影响

以生污泥为材料,研究单质硫(浓度分别为5、10、20 g/L)、FeSO4?7H2O (浓度分别为10、20 g/L）和硫代硫酸钠（浓度分别为10、20 g/L）三种底物的不同浓度对污泥中Zn、Cu、Pb、Cd、Cr和Ni六种重金属生物淋滤效果的影响。结果表明：单质硫的致酸性最好,第4天pH值就达到2.0左右,Zn、Cu、Pb、Cr和Ni的滤出量最大（原污泥Cd未检出）,并以底物投放浓度在10～20 g/L为佳。FeSO4?7H2O的致酸性和重金属滤出量较单质硫弱。硫代硫酸钠在浓度10 g/L时,致酸性和重金属的滤出量介于单质硫和FeSO4?7H2O之间,但浓度20 g/L时滤液呈碱性,重金属难于滤出甚至不滤出。     

Biological Degradation of Crude Oil Refinery Sludge with Commercial Surfactant and Sewage Sludge by Co-Composting

This study determined the potential of surfactant and sewage sludge in enhancing degradation of oil sludge. A mixture of oil sludge, surfactant, and sewage sludge was co-composted for 24 weeks in the laboratory. Physical and chemical parameters in the compost were measured every four weeks. Isolated microorganisms were characterized by molecular techniques. The pH in all experiments remained between 8 and 6.4. CO₂ evolution reached 5503 µg/dwt/day by the twenty-fourth week. The dominant bacterial species were Acinectobacter, Rodococcus, mycobacterium, Pseudomonas, Bacillus, Arthrobacter, and Staphylococcus species and fungi were Pleurotus, Penicillium, and Aspergillus sp. TPH was reduced by 92% in the sewage sludge and surfactant treatment, 75 and 81% in other treatments, and 44.2% in the control. PAH concentrations were reduced by between 75 and 100%. The results indicate that a careful application of surfactant and sewage sludge could enhance oil sludge degradation in a compost system.     

Effects of Sewage Sludge on Plant Community Composition in Restored Limestone Quarries

The effects of sewage sludge, used to improve fertility of replaced soil, on vegetation were studied in limestone quarry restoration. Plant community growing in the first stages after sludge application was surveyed in six quarries of NE Spain. Areas with a mixture of sewage sludge and residual soil were compared to areas where the application consisted only of residual soil (a mixture of previous top soil and mine spoils). Sewage sludge was hypothesized to increase total biomass and cover, modifying species composition and delaying the early successional recover of the community. The results showed that both biomass and plant cover increased because of sewage sludge addition. The floristic composition was dominated by ruderal species that did not show any dependence on sewage sludge application. Convergence on similarity between sludge and control plots was not detected along a 5‐year period. Although species richness was significantly lower in sludge plots, diversity and equitability indexes did not show differences between treatments. The results did not show differences in the proportion of non‐native species. The proportion of legumes was lower in sludge plots. These results show that the plant communities resulting from the addition of sewage sludge to the soil used in limestone quarry restoration have more biomass and cover, but less number of species, and they do not show a clear trend to converge to those areas restored only with non‐amended soil.     

Impact of Anaerobic and Aerobic Processes on PolyChloroBiphenyl Removal in Contaminated Sewage Sludge

Aerobic and anaerobic biodegradation of six priority PCBs was investigated in continuous stirred tank reactors fed with naturally contaminated sewage sludge. Anaerobic and aerobic abiotic losses were higher for the lightly chlorinated PCBs but remained for all PCBs below 20%. Under strict methanogenic conditions, PCB removals were about 40% whatever PCB molecular weight or their degree of chlorination. However, considering abiotic losses, the heaviest PCBs were more efficiently anaerobically biodegraded probably because of higher dechlorination rates. The aerating sludge process enhanced removal of the lightest chlorinated PCBs from 40% up to 100%, while removal rates of the heaviest PCBs remained around 40%. Although the mesophilic aerobic process exhibits better removal efficiencies because of operating conditions, the results suggest that PCB biodegradation was strongly limited by their bioavailability in naturally contaminated sludge, under both redox conditions. Indeed, since PCB removal was closely linked to the solid reduction rates, PCB bioavailability was likely the limiting factor for biodegradation. As a consequence, the raw PCB concentrations (in mg kg^–1_{dry weight}) which are concerned by legislative procedures did not decrease sufficiently in both processes to reach a limit value fulfilling the current French/European regulation about PCB contents in sewage sludge before spreading on agricultural land.     

The Effects of Bacterial Leaching on Metal Partitioning in Sewage Sludge

The partitioning of Mn, Al, Zn, Cu and Ti ions in municipal sewage sludge was investigated before and after bioleaching processes effectuated by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Oxidation–reduction potential increase and pH decrease were obtained as a result of bacterial activity. A less pronounced and constant decrease was obtained with A. ferrooxidans, whereas A. thiooxidans presented a lag phase before a steep pH decrease. Metal solubilization was accomplished in experimental systems supplemented with energy source, Fe²⁺ for A. ferrooxidans and S⁰ for A. thiooxidans. Solubilization efficiency differed for each metal except for Al, and was relatively similar for either organism. Metal partitioning was conducted using a five-step sequential extraction procedure before and after the bioleaching. The results indicated that Zn and Mn ions were mostly associated with the organic fraction, whereas Cu, Al and Ti ions with the sulphide/residue fraction. The bioleaching process caused prompt solubilization of metals mostly associated with the more labile fractions (exchangeable, adsorbed and organically bound metals), whereas those associated to the less labile ones (EDTA and sulphide/residue fractions) were exchanged towards more labile fractions.     

Effects of Municipal Sewage Sludge Doses on the Chlorophyll Contents and Heavy Metal Concentration of Sugar Beet (Beta vulgaris var. saccharifera)

The present study was conducted to assess the suitability of sewage sludge amendment (SSA) in soil for Beta vulgaris var. saccharifera (sugar beet) by evaluating the heavy metal accumulation and physiological responses of plants grown at a 10%, 25%, and 50% sewage sludge amendment rate. The sewage sludge amendment was modified by the physicochemical properties of soil, thus increasing the availability of heavy metals in the soil and consequently increasing accumulation in plant parts. Cd, Pb, Ni, and Cu concentrations in roots were significantly higher in plants grown at 25% as compared to 50% SSA; however, Cr and Zn concentration was higher at 50% than 25% SSA. The concentrations of heavy metal showed a trend of Zn > Ni > Cu > Cr > Pb > Cd in roots and Zn > Cu > Ni > Cr > Pb > Cd in leaves. The only instance in which the chlorophyll content did not increase after the sewage sludge treatments was 50%. There were approximately 1.12-fold differences between the control and 50% sewage sludge application for chlorophyll content. The sewage sludge amendment led to a significant increase in Pb, Cr, Cd, Cu, Zn, and Ni concentrations of the soil. The heavy metal accumulation in the soil after the treatments did not exceed the limits for the land application of sewage sludge recommended by the US Environmental Protection Agency (US EPA). The increased concentration of heavy metals in the soil due to the sewage sludge amendment led to increases in heavy metal uptake and the leaf and root concentrations of Ni, Zn, Cd, Cu, Cr, Pb, and Zn in plants as compared to those grown on unamended soil. More accumulation occurred in roots and leaves than in shoots for most of the heavy metals. The concentrations of Cd, Cr, and Pb were more than the permissible limits of national standards in the edible portion of sugar beet grown on different sewage sludge amendment ratios. The study concludes that the sewage sludge amendment in the soil for growing sugar beet may not be a good option due to risk of contamination of Cr, Pb, and Cd.     

Effects of Sewage Sludge on the Growth of Potted Salt Marsh Plants Exposed to Natural Tidal Inundation

Abstract A growth experiment with native plants in pots exposed to natural environmental conditions evaluates the use of sewage sludge as a soil amendment in restoration of a southern California salt marsh. Sludge containing desirable organic matter but also undesirable heavy metal contaminants was mixed with a readily available matrix soil to reduce metal concentrations to levels below legal limits for land applications of sludge. Soil nutrient analysis revealed expected increases in total nitrogen and total phosphorus content with increasing sludge concentration. Soil metals analysis, however, revealed decreases in metal content with increased sludge concentration, a trend evidently caused by higher than expected metal content in the matrix soil. Five artificial soil mixtures ranging from 0 to 70% sludge were accompanied by natural wetland soil controls. Pots containing these soils were placed into a natural salt marsh. The pots were then planted with two native salt marsh plant species, Salicornia virginica and Frankenia grandifolia. Aboveground biomass was harvested after 12 months. Plant growth displayed no obvious change with increasing sludge concentration. Over the concentration ranges used, increased nutrient content did not stimulate plant growth and increased metal content did not inhibit plant growth. Plants grew better in natural wetland soil than in artificial soil mixtures, a trend probably caused by the substantially finer texture and higher organic content of natural soil. All sludge treatments differed more from the natural soil than from each other, implying that within the ranges examined, soil texture and organic content exerted more influence on plant growth than did metal or nutrient concentration. These results suggest that incorporating this sewage sludge in the soil of the restored salt marsh will neither benefit nor harm the plants that will live there and that greatest plant growth will be achieved by mixing the sludge with a fine‐grained matrix soil.     

Mobility and Distribution of Zinc,Cadmium and Lead in Calcareous Soils Receiving Spiked Sewage Sludge

Leaching column experiments were conducted to determine the degree of mobility and the distribution of zinc (Zn), cadmium (Cd), and lead (Pb) because of an application of spiked sewage sludge in calcareous soils. A total of 20 leaching columns were set up for four calcareous soils. Each column was leached with one of these inflows: sewage sludge (only for two soils), spiked sewage sludge, or artificial well water (control). The columns were irrigated with spiked sewage sludge containing 8.5 mg Zn l^?1, 8.5 mg Cd l^?1, and 170 mg Pb l^?1 and then allowed to equilibrate for 30 days. At the end of leaching experiments, soil samples from each column were divided into 18 layers, each being 1 cm down to 6 cm and 2 cm below that, and analyzed for total and extractable Zn, Cd and Pb. The fractionation of the heavy metals in the top three layers of the surface soil samples was investigated by the sequential extraction method. Spiked sewage sludge had little effect on metal mobility. In all soils, the surface soil layers (0-1 cm) of the columns receiving spiked sewage sludge had significantly higher concentrations of total Zn, Cd and Pb than control soils. Concentration of the heavy metals declined significantly with depth. The mobility of Zn was usually greater than Cd and Pb. The proportion of exchangeable heavy metals in soils receiving spiked sewage sludge was significantly higher than that found in the control columns. Sequential extraction results showed that in native soils the major proportion of Zn and Pb was associated with residual (RES) and organic matter (OM) fractions and major proportion of Cd was associated with carbonate (CARB) fraction, whereas after leaching with spiked sewage sludge, the major proportion of Zn and Pb was associated with Fe-oxcide (FEO), RES, and CARB fractions and major proportion of Cd was associated with CARB, RES and exchangeable (EXCH) fractions. Based on relative percent, Cd in the EXCH fraction was higher than Zn and Pb in soils leached with spiked sewage sludge.     

Natural Estrogens in the Surface Water of Shenzhen and the Sewage Discharge of Hong Kong

Despite the fact that estrogens cause hormonal disturbances in aquatic organisms, few studies on the estrogen contamination in our surface waters have been conducted. This study was thus conducted (1) to investigate the level of estrogens in the surface waters in Shenzhen and (2) to examine the estrogen levels in the sewage discharges in Hong Kong. Total estrogens (estrone E1, estradiol E2, and estriol E3) in the samples taken from two reservoirs, five rivers, and thirty sampling locations of the seawater in Shenzhen were measured by using ELISA kits. The preliminary results have revealed that the level of estrogens in the surface waters of Shenzhen is generally higher than that in the similar water bodies in well-developed nations. Sewage could be the major source of the estrogen contamination in these waters. The total estrogens levels in the Xili and Shenzhen Reservoirs were in a range of 3–11 ng/L with a mean value of 7 ng/L, where that in four rivers in Shenzhen were found to be 47–90 ng/L and 60.25 ng/L, respectively. In the seawater near the sewage discharge points they were 260–300 ng/L and 287 ng/L, respectively. The estradiol levels in the influent and effluent of three sewage treatment works (STWs) in Hong Kong were also monitored. The activated sludge process used in these STWs removed more than 80% whereas the chemical coagulation processed used at the Stonecutters Island STW removed less estrogens. Biological treatment appears to play a significant role in removing estrogens from wastewater.