生物沥滤污泥土地利用适用性分析

研究了污泥生物沥滤对重金属(Cu、Pb和Zn)形态、营养物质和SO42-存在形式的影响,分析生物沥滤污泥土地利用的适用性。结果表明:生物沥滤后,污泥上清液中重金属通过固液分离而去除,污泥中Cu、Pb和Zn的去除率分别为84.1%、34.8%和80.0%,残存于污泥中的重金属含量大幅降低,且生物有效性低,提高了污泥土地利用的安全性。污泥经生物沥滤后氮、磷和钾的流失分别为38.2%、52.1%和42.8%,但仍能保持较好的肥效。采用X-射线衍射光谱分析发现,残留于污泥中的SO24-主要与Ca2 相结合,较为稳定,生物沥滤后的污泥施用于土地后对环境影响较小。     

New protocol for the rapid quantification of exopolysaccharides in continuous culture systems of acidophilic bioleaching bacteria

In this study, we investigate exopolysaccharide production by a bacterial consortium during the bioleaching of a cobaltiferrous pyrite. Whereas comparable studies have looked at exopolysaccharide production in batch systems, this study focuses on a continuous system comprising a series of four stirred bioreactors and reveals the difficulties in quantifying biomolecules in complex media such as bioleached samples. We also adapted the phenol/sulphuric acid method to take into account iron interference, thus establishing a new protocol for sugar quantification in bioleached samples characterised by low pH (1.4) and high iron concentration (2 g l⁻¹). This allows sugar analysis without any prior sample preparation step; only a small amount of sample is needed (0.5 ml) and sample preparation is limited to a single filtration step. We found that free exopolysaccharides represented more than 80% of the total sugars in the bioreactors, probably because stirring creates abrasive conditions and detaches sugars bound to pyrite or bacteria and that they were produced mainly in the first two reactors where bioleaching activity was greatest. However, we could not establish any direct link between the measured exopolysaccharide concentration and bioleaching activity. Exopolysaccharides could have another role (protection against stress) in addition to that in bacterial attachment.     

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。     

Bioleaching of Heavy Metals from Textile Sludge by Indigenous Sulfur-and-Iron-Oxidizing Microorganisms Using Elemental Sulfur and Ferrous Sulfate as Energy Sources: A Comparative Study

The present study was undertaken to investigate the potential of enriched indigenous sulfur-and-iron-oxidizing microorganisms in the bioleaching of Cu, Ni, Zn and Fe from textile sludges by using elemental sulfur and ferrous sulfate (FS), respectively, as an energy source under batch conditions. The experiments were performed with three different textile sludges (S1, S2 and S3) at initial neutral pH of the sludges procured from different parts of the country i.e., UP, Haryana and Punjab. The three sludges used were not only procured from different parts of the country but also differ in physiochemical characteristics. The extent of heavy metals solubilization in each sludge was found to be different using sulfur- and iron-oxidizing microorganisms. The results of the study indicate that sulfur-oxidizing microorganisms were found more efficient in the bioleaching process, irrespective of any sludge. The use of sulfur-oxidizing microorganisms led to higher solubilization of heavy metals and after 7 days of bioleaching about 84–96% Cu, 64–78% Ni, 81–92% Zn and 74–88% Fe were removed compared to 62–73% Cu, 62–66% Ni, 74–78% Zn and 70–78% Fe using iron-oxidizing microorganisms. This study had shown the feasibility of applying the bioleaching process to textile sludge contaminated with heavy metals. The results of the present study indicate that the bioleached sludge would be safer for land application.     

Role of Iron-Oxidizing Microorganism in Bioleaching of Heavy Metals From Sewage Sludge Contaminated with Textile Dyes

This article reports the role of indigenous iron-oxidizing microorganisms in bioleaching of heavy metals from anaerobically digested sewage sludge in presence of toxic dyes namely, methylene blue (MB), Remazol black B (RBB) and mixture of both the dyes (DM). To achieve this goal, different concentrations of dyes (0, 500, 10,000, 15,000 and 25,000 mg/L) were added to the sewage sludge (initial pH ～ 7) and subsequently, the solubilization of heavy metals (Cu, Ni, Zn and Cr) was measured at time intervals of 48 h for 16 days. The results showed that an increase in dye concentration adversely affected the population of indigenous iron-oxidizing microorganisms, thereby decreased the bioleaching of metals. The metal solubilization from sludge is more adversely affected in presence of RBB and DM than MB. In majority of cases, the maximum metal solubilization was recorded at dye concentration of 5,000 mg/L. Two factor analyses (ANOVA) suggests the impact of both factors: dye concentration and dye type on metal leaching rate in sludge system.     

Growth and biocatalytic activities of aerobic thermophilic populations in sewage sludge

Summary Enzymatic activities of aerobic thermophilic microorganisms are described and investigated for the development and control of sewage sludge treatment processes in batch and fed-batch cultures. Proteolytic activity is the main enzymatic activity in an aerobic thermophilic sewage sludge treatment process. It has an optimum at 80°C and can be found also during growth on synthetic media. The activity is correlated with the increase in ammonium in the particle-free fraction and the values of the respiratory quotients during cultivation either in sewage sludge or in a syntheticc medium. No other extracellular activities (lipase, amylase, pectinase and cellulase) were detected in the investigated sludge samples. Carbohydrates, lipids and other polymers were either not present in significant amounts or passed with only minor modifications through the treatment. Cultivations in sewage sludge were either oxygen or carbon limited. One strain able to excrete lysozyme was isolated. It might have a synergistic effect on the heat inactivation of pathogenic microorganisms (cryptic growth) although lytic activity remained very low. Two-thirds of the entire metabolic activity is due to degradation of insoluble matter. The utilization of particulate matter also has a positive influence on the efficiency of the process by reduction in dry matter and increase in water-removal properties. Even at extremely low aeration rates, the acidification effect was small. Only small amounts of isobutyrate, isovaleriate and 2-methylbutyrate were formed at extremely low aeration rates and caused an increase in the total volatile fatty acid content after 12 and 36 h cultivation time.     

Influence of bulking agent on sewage sludge composting process

Four types of compost, consisting of mixtures of Acacia dealbata (A) with sewage sludge (SS) were studied in a laboratory reactor. Composting time was 80 days and parameters monitored over this period included temperature, organic matter, pH, CO₂, O₂, C/N ratio, Kjeldahl-N, as well as maturity indexes. All the studied parameters were influenced by the bulking amount used. The highest profile temperature measured was for the A/SS 1/2 (w/w) mixture that reached a maxima temperature of 67 °C and lower maximum temperatures of 52, 48 and 46 °C were observed for A/SS 1/3, 1/1 and 1/0 composts, respectively. The kinetic model used showed that a descent of sewage sludge in the composting mixtures favored the enzyme–substrate affinity. However, an increase in depending on the parameters of the process factors was observed when the sewage sludge ratio was increased in mixtures. The optimal amounts of sewage sludge for co-composting with Acacia indicate that moderate amounts of sludge (1/1) would be the best compromise.     

Impact of application of organic waste materials on microbial and enzyme activities of mine soils in the Lusatian coal mining region

The objective of the present work was to study the short-term stimulation of microbial and enzyme activity in mine soils by application of organic waste materials in lysimeter and mesocosm studies. The mine soils derived from tertiary and quaternary deposits were ameliorated with brown coal filter ash (tertiary deposits) and lime (quaternary deposits). At the beginning of recultivation the soils were treated with varying amounts of sewage sludge, coal sludge, composted sewage sludge and compost to a depth of 30 cm. In the first 2 years after application of organic waste materials we found a very low level of microbial properties especially in the sandy materials from quaternary deposits but a significant increase in microbial respiration, substrate induced respiration and enzyme activities like invertase and alkaline phosphatase with increasing application rates of sewage sludge, compost and sewage sludge mixed with coal sludge. This can be explained by an increase in organic matter and nutrient content of the soils and an improvement of soil physical properties such as water and nutrient retention capacity. Additionally it can be assumed, that constituents of the coal admixtures of tertiary deposits can be mineralised or converted by the soil microorganisms. In the tertiary materials ameliorated with brown coal ash the highest amounts of microbial and enzyme activities were measured after application of nitrogen-rich sewage sludge or very high amounts of mature compost mainly consisting of green waste. Compared with sewage sludge the stimulating effects of composted sewage sludge were quite lower because of organic matter fragmentation and a reduced energy and nutrient supply to soil microorganisms. This revised version was published online in June 2006 with corrections to the Cover Date.     

Adaptive changes of chemolithoautotrophic acidophilic sulfur-oxidizing bacteria during growth in sewage sludge

A chemolithoauthotrophic, acidophilic, sulfur-oxidizing strain was isolated from sewage sludge and identified as Acidithiobacillus thiooxidans. The morphology and physiology of the isolate grown in mineral medium or sterilized sewage sludge were investigated. Morphological and ultrastructural differences between cells grown in mineral medium and sewage sludge were clearly visible. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed some changes in the protein expression profiles in the periplasmic fraction as well as a lower level of cytochromes. Adaptation of A. thiooxidans to sewage sludge was not only a physiological process but also included genetic changes. Restriction fragment length polymorphism analysis using pulsed field gel electrophoresis showed structural changes in chromosomal DNA of such bacteria. Most of the restriction fragments were highly conserved and shared by strains grown under different conditions. Cultivation in mineral medium did, however, lead to the appearance of an additional restriction fragment. In combination, the obtained results provide evidence of adaptive responses by A. thioxidans during growth in sewage sludge and confirm that this bacteria can be useful in biotechnologies of heavy metal bioleaching from different environments polluted with hazardous compounds.     

Tolerance to copper and zinc of Acidithiobacillus thiooxidans isolated from sewage sludge

The effect of copper and zinc ions on sulphur oxidation by Acidithiobacillus thiooxidans, strain SFR01, isolated from anaerobic sewage sludge was assessed, resulting in tolerance levels up to 20 and 200 mmol l^–1 for copper and zinc, respectively. The tolerance levels obtained were higher than the concentration of copper and zinc usually found in the collected sewage sludge. The tolerance levels obtained indicate no constraints for sludge bioleaching of those metals due to their toxicities to the indigenous A. thiooxidans.     

Acidification of methanol-fed anaerobic granular sludge bioreactors by cobalt deprivation: Induction and microbial community dynamics

The acidification of mesophilic (30 degrees C) methanol-fed upflow anaerobic sludge bed (UASB) reactors induced by cobalt deprivation from the influent was investigated by coupling the reactor performance (pH 7.0; organic loading rate 4.5 g COD . L(-1) . d(-1)) to the microbial ecology of the bioreactor sludge. The latter was investigated by specific methanogenic activity (SMA) measurements and fluorescence in situ hybridization (FISH) to quantify the abundance of key organisms over time. This study hypothesized that under cobalt limiting conditions, the SMA on methanol of the sludge gradually decreases, which ultimately results in methanol accumulation in the reactor effluent. Once the methanol accumulation surpasses a threshold value (about 8.5 mM for the sludge investigated), reactor acidification occurs because acetogens outcompete methylothrophic methanogens at these elevated methanol concentrations. Methanogens present in granular sludge at the time of the acidification do not use methanol as the direct substrate and are unable to degrade acetate. Methylotrophic/acetoclastic methanogenic activity was found to be lost within 10 days of reactor operation, coinciding with the disappearance of the Methanosarcina population. The loss of SMA on methanol can thus be used as an accurate parameter to predict reactor acidification of methanol-fed UASB reactors operating under cobalt limiting conditions.     

Effects of L-cysteine on Ni-Cu sulfide and marmatite bioleaching by Acidithiobacillus caldus

The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide and marmatite were studied with a moderately thermophilic, sulfur-oxidizing bacterium, strain of Acidithiobacillus caldus. X-ray diffraction (XRD) observations showed the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. It was found that adding certain amounts of L-cysteine to the leaching system of Ni-Cu sulfide largely enhanced the leaching rate, while L-cysteine inhibited the bioleaching of marmatite by A. caldus. The mechanism of L-cysteine interaction with mineral surfaces was studied by means of zeta potential determination and IR spectra.     

Influences of Extracellular Polymeric Substances on the Dewaterability of Sewage Sludge during Bioleaching

Extracellular polymeric substances (EPS) play important roles in regulating the dewaterability of sludge. This study sought to elucidate the influence of EPS on the dewaterability of sludge during bioleaching process. Results showed that, in bioleaching system with the co-inoculation of Acidithiobacillus thiooxidans TS6 and Acidithiobacillus ferrooxidans LX5 (A. t+A. f system), the capillary suction time (CST) of sludge reduced from 255.9 s to 25.45 s within 48 h, which was obviously better than the controls. The correlation analysis between sludge CST and sludge EPS revealed that the sludge EPS significantly impacted the dewaterability of sludge. Sludge CST had correlation with protein content in slime and both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers, and the decrease of protein content in slime and decreases of both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers improved sludge dewaterability during sludge bioleaching process. Moreover, the low sludge pH (2.92) and the increasing distribution of Fe in the solid phase were another two factors responsible for the improvement of sludge dewaterability during bioleaching. This study suggested that during sludge bioleaching the growth of Acidithiobacillus species resulted in the decrease of sludge pH, the increasing distribution of Fe in the solid phase, and the decrease of EPS content (mainly including protein and/or polysaccharide) in the slime, TB-EPS, and Slime+LB+TB layers, all of which are helpful for sludge dewaterability enhancement.     

Reuse of waste materials as growing media for ornamental plants

The use of different waste materials: pine bark, coconut fibre and sewage sludge as substrates in the production of ornamental plants was studied, with an special interest on the suitability of coconut fibre as growing substrate for conifer plants. The plant species tested were Pinus pinea, Cupressus arizonica and C. sempervirens and the substrate mixtures were: (1) pine bark, (2) pine bark with 15% of sewage sludge compost, (3) pine bark with 30% of sewage sludge compost, (4) coconut fibre, (5) coconut fibre with 15% of sewage sludge compost and (6) coconut fibre with 30% of sewage sludge compost. Substrates were physically and chemically well characterized, and 75-cm plants were grown on them for one year. Plant and substrate status were periodically tested along the experiment. As biosolid recycling is the main objective of the present work, the mixtures with 30% of composted sewage sludge will be the most convenient substrate to use. For C. sempervirens and C. arizonica, a mixture between pine bark or coconut fibre and 30% of biosolid compost in volume gave the best results, but the lower cost of the pine bark than the coconut fibre substrate indicated the use of the PB+30% CSS. For P. pinea the research of new combinations between waste products is recommended to attain better results.     

The effect of sewage sludge flooding on growth and morphometric parameters of Phragmites australis (Cav.) Trin. ex Steudel

Phragmites australis is the most frequently used species in constructed wetlands (CW) for dewatering and mineralization of sludge. Such CW create a very hostile environment for plants because their roots are exposed to permanently anaerobic conditions. Our working hypothesis assumed a simple relationship between the success of reed in colonising sludge flood stands and maximalisation of shoot oxygen production and transport to rhizomes and roots. Morphometric parameters and density of common reed shoots growing in reed bed systems inundated with sewage sludge were investigated. It was proved that flooding with sewage sludge significantly influenced characteristics of common reed populations. In comparison with natural stands, on stands treated with sewage sludge, maximal density of shoots was higher, biomass was twice as high, shoot diameter was significantly greater, and leaf weight ratio of an individual shoot was also significantly higher. Tendency to shorten shoots was noted. Growing period was longer for reed shoots treated with sewage sludge than on natural stands.     

Solubilization profiles of metal ions from bioleaching of sewage sludge as a function of pH

Two patterns of solubilization of metal ions resulting from bioleaching of sewage sludge by sulphur-oxidizing Thiobacillus spp. were established as a function of pH. Chromium and copper ions required a pH of 2–3 to initiate their solubilization, whereas nickel and zinc ions had their solubilization initiated at pH 6–6.5. The patterns obtained were independent of the sludge solids concentrations investigated (10, 17, 25, 32.5 and 40 g l^–1).     

异养微生物在金属生物淋滤技术中的应用

生物淋滤技术主要应用于低品位矿石金属选矿、煤气脱硫、废弃物中金属回收和污染介质中金属离子毒性的去除等方面。作为生物淋滤技术中的主体微生物之一,异养微生物可通过其产生的酸性代谢物还原、酸化及络合,提取或者溶解非硫化矿、固体废弃物、污水污泥及土壤中的金属,有助于解决目前的资源短缺问题,还可对污染环境治理提供技术支持,具有重要的理论意义和实践价值。应用于异养微生物淋滤技术中的常见微生物包括细菌(以假单胞菌为主)和真菌(以曲霉菌和青霉菌应用最为广泛)。淋滤过程涉及酸解、络合、还原及碱化等。目前,异养微生物淋滤技术主要应用于生物冶金、固体废弃物处理、污水处理和污染土壤修复等。本文分析了异养微生物金属淋滤过程中的问题,并提出了未来研究的发展方向。     

Optimization of staged bioleaching of low-grade chalcopyrite ore in the presence and absence of chloride in the irrigating lixiviant: ANFIS simulation

In this investigation, copper was bioleached from a low-grade chalcopyrite ore using a chloride-containing lixiviant. In this regard, firstly, the composition of the bacterial culture media was designed to control the cost in commercial application. The bacterial culture used in this process was acclimated to the presence of chloride in the lixiviant. Practically speaking, the modified culture helped the bio-heap-leaching system operate in the chloridic media. Compared to the copper recovery from the low-grade chalcopyrite by bioleaching in the absence of chloride, bioleaching in the presence of chloride resulted in improved copper recovery. The composition of the lixiviant used in this study was a modification with respect to the basal salts in 9 K medium to optimize the leaching process. When leaching the ore in columns, 76.81 % Cu (based on solid residues of bioleaching operation) was recovered by staged leaching with lixiviant containing 34.22 mM NaCl. The quantitative findings were supported by SEM/EDS observations, X-ray elemental mapping, and mineralogical analysis of the ore before and after leaching. Finally, Adaptive neuro-fuzzy inference system (ANFIS) was used to simulate the operational parameters affecting the bioleaching operation in chloride–sulfate system.     

Direct and Indirect Bioleaching of Cobalt from Low Grade Laterite and Pyritic Ores by Aspergillus niger

Abstract

The bioleaching efficiency and mechanism of recovery of cobalt (Co) and nickel from laterites and pyritic ores by Aspergillus niger were investigated. Recoveries of Co from laterites and pyritic ores by direct bioleaching were 65.9?±?1.8% and 4.9?±?2.7%, respectively, while 30.9?±?0.6% and 10.9?±?6.2% recovery of Ni were obtained from laterites and pyritic ores, respectively. Recovery of Co via indirect bioleaching in the absence of the fungal biomass from laterite was significantly lower when compared with Co released by direct bioleaching. In the latter, hyphal penetration and colonization of the laterites were clearly observed by scanning electron microscopy (SEM). X-ray powder diffraction (XRPD) analysis of mineral phases before and after bioleaching indicated that cobalt-bearing goethite was the main phase bioleached in the laterites. No significant difference was found between Co recoveries from synthesized cobalt-bearing goethite by both direct and indirect bioleaching. Therefore, we propose that two processes are involved in bioleaching from laterites: (1) cobalt-bearing goethite was exposed via direct interactions between the fungus and the minerals and (2) cobalt-bearing goethite was dissolved by released metabolites of A. niger, such as organic acids. An incongruent pattern of Co and Fe bioleaching from the laterites was also a feature of the metal recovery process.     

Conversion of sewage sludge into lipids by Lipomyces starkeyi for biodiesel production

The potential of accumulation of lipids by Lipomyces starkeyi when grown on sewage sludge was assessed. On a synthetic medium, accumulation of lipids strongly depended on the C/N ratio. The highest content of lipids was measured at a C/N-ratio of 150 with 68% lipids of the dry matter while at a C/N-ratio of 60 only 40% were accumulated. Within a pH range from 5.0 to 7.5 the highest lipid accumulation was found at pH 5.0 while the highest yield per litre was pH 6.5. Although sewage sludge had no inhibitory effects on growth or accumulation on L. starkeyi when added to synthetic medium, there was no significant growth on untreated sewage sludge. However, pretreatment of sludge by alkaline or acid hydrolysis, thermal or ultrasonic treatment lead to accumulation of lipids by L. starkeyi with highest values of 1 g L(-1) obtained with ultrasound pre-treatment. Based on the content of free fatty acids and phosphorus, lipids accumulated from sewage sludge could serve as a substrate for the production of biodiesel.