Intensive bioconversion of sewage sludge and food waste by Bacillus thermoamylovorans

The main aim of this work was to intensify conventional composting of a mixture of sewage sludge and solid food wastes by a one-stage thermophilic bioconversion of these wastes into an organic fertilizer. An intensive process was carried out in a closed system, with or without addition of a starter culture of Bacillus thermoamylovorans. The most effective thermophilic bioconversion of the mixture of food waste and sewage sludge, with addition of starter culture, was when the pH was buffered with calcium carbonate, or the pH drop in the material was prevented by preliminary removal of sulphides from sewage sludge by hydrogen peroxide.     

Codigestion of olive oil mill wastewaters with manure, household waste or sewage sludge

Combined anaerobic digestion of oil mill effluent(OME) together with manure, household waste (HHW) orsewage sludge was investigated. In batch experimentsit was shown that OME could be degraded into biogaswhen codigested with manure. In codigestion with HHWor sewage sludge, OME dilution with water (1:5) wasrequired in order to degrade it. Using continuouslystirred lab-scale reactors it was shown thatcodigestion of OME with manure (50:50 and 75:25 OMEto manure ratios) was successful with a theoreticalOME utilization of 75% and with approx. 87%reduction of the lipids content in OME. An OMEutilization of approx. 55%, and lipid reduction of73% was reached in codigestion with HHW (50:50 and75:25 OME to HHW ratios). The results showed thatthe high buffering capacity contained in manure,together with the content of several essentialnutrients, make it possible to degrade OME withoutprevious dilution, without addition of externalalkalinity and without addition of external nitrogensource.     

Microbial population dynamics during start-up and overload conditions of anaerobic digesters treating municipal solid waste and sewage sludge

Microbial population dynamics were investigated during start-up and during periods of overload conditions in anaerobic co-digesters treating municipal solid waste and sewage sludge. Changes in community structure were monitored using ribosomal RNA-based oligonucleotide probe hybridization to measure the abundance of syntrophic propionate-oxidizing bacteria (SPOB), saturated fatty acid-beta-oxidizing syntrophs (SFAS), and methanogens. These changes were linked to traditional performance parameters such as biogas production and volatile fatty acid (VFA) concentrations. Digesters with high levels of Archaea started up successfully. Methanosaeta concilii was the dominant aceticlastic methanogen in these systems. In contrast, digesters that experienced a difficult start-up period had lower levels of Archaea with proportionally more abundant Methanosarcina spp. Syntrophic propionate-oxidizing bacteria and saturated fatty acid-beta-oxidizing syntrophs were present at low levels in all digesters, and SPOB appeared to play a role in stabilizing propionate levels during start-up of one digester. Digesters with a history of poor performance tolerated a severe organic overload event better than digesters that had previously performed well. It is hypothesized that higher levels of SPOB and SFAS and their methanogenic partners in previously unstable digesters are responsible for this behavior.     

A comparison study on the high-rate co-digestion of sewage sludge and food waste using a temperature-phased anaerobic sequencing batch reactor system

Assessing contemporary anaerobic biotechnologies requires proofs on reliable performance in terms of renewable bioenergy recovery such as methane (CH₄) production rate, CH₄ yield while removing volatile solid (VS) effectively. This study, therefore, aims to evaluate temperature-phased anaerobic sequencing batch reactor (TPASBR) system that is a promising approach for the sustainable treatment of organic fraction of municipal solid wastes (OFMSW). TPASBR system is compared with a conventional system, mesophilic two-stage anaerobic sequencing batch reactor system, which differs in operating temperature of 1st-stage. Results demonstrate that TPASBR system can obtain 44% VS removal from co-substrate of sewage sludge and food waste while producing 1.2 m³CH₄/m³_system/d (0.2 m³CH₄/kgVS_added) at organic loading rate of 6.1 gVS/L/d through the synergy of sequencing-batch operation, co-digestion, and temperature-phasing. Consequently, the rapid and balanced anaerobic metabolism at thermophilic stage makes TPASBR system to afford high organic loading rate showing superior performance on OFMSW stabilization.     

Keratinolytic fungi in sewage sludge

Sewage sludge from the Upper Silesia Region of Poland were surveyed for keratinolytic fungi. Out of 100 Petri dishes examined, 89 were positive for these micro-organisms. Altogether, 185 fungal appearances belonging to 10 species were observed. Trichophyton terrestre with its teleomorph Arthroderma quadrifidum, T. ajelloi with A. uncinatum, Microsporum gypseum with Arthroderma sp., and Chrysosporium keratinophilum with Aphanoascus keratinophilus prevailed in the sludges. The sewage treatment technologies together with the sludge structure, humidity and pH were found to be critical factors determining the occurrence of keratinolytic fungi in the sludge environment. The qualitative and quantitative composition of keratinolytic fungi could be a useful tool in evaluation of sludge treatment processes.     

城市污泥添加厨余垃圾厌氧发酵产挥发性脂肪酸的研究

为了考察污泥产酸工业化的可行性和添加食品废弃物对污泥产酸的影响,本实验在实验室的基础上进行扩大研究,考察了不同的底物总固体浓度对产挥发性脂肪酸的影响.结果显示添加厨余垃圾之后挥发性脂肪酸的累积量可达到17.62g/L.综合产挥发性脂肪酸效果、底物降解效果和产率等情况建议在较大规模的生产过程中选择130g/L的底物浓度为...     

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.     

Eliminating methanogenic activity in hydrogen reactor to improve biogas production in a two-stage anaerobic digestion process co-digesting municipal food waste and sewage sludge

Laboratory scale two-stage anaerobic digestion process model was operated for 280 days to investigate the feasibility to produce both hydrogen and methane from a mixture feedstock (1:1 (v/v)) of municipal food waste and sewage sludge. The maximum hydrogen and methane yields obtained in the two stages were 0.93 and 9.5 mL/mL feedstock. To eliminate methanogenic activity and obtain substantial hydrogen production in the hydrogen reactor, both feedstock and mixed liquor required treatment. The heat treatment (100 °C, 10 min) for feedstock and a periodical treatment (every 2-5 weeks, either heating, removal of biomass particles or flushing with air) for mixed liquor were effective in different extent. The methane production in the second stage was significantly improved by the hydrogen production in the first stage. The maximum methane production obtained in the period of high hydrogen production was more than 2-fold of that observed in the low hydrogen production period.     

Distribution of heavy metals in a sewage oxidation pond and their adsorption in residual solid (sewage sludge ash)

Abstract

Electrometric studies were carried out on the interaction of heavy metal ions such as manganese, chromium, nickel, copper, zinc, cadmium and lead with the extracted organic matter, humic and fulvic acid from the sludge in a sewage oxidation pond. The distribution of heavy metals was between 60 and 97%, which is associated with the solid waste (sludge) of the oxidation pond. The adsorption/removal efficiency of metal ions onto the sludge ash was more than 90% and 97%, respectively, in the pure system. To obtain the ash, the sludge was burnt at 500°C, treated with nitric acid (1+1) to leach out all the metals and then filtered; the residue left on the filter paper was the pure ash. Both this and that coated with organic matter were studied. The adsorption isotherm for metals, humic/fulvic acids and metal-humic/fulvic acid complexes in the metal-free sludge ash and in the organic matter in the pure system were studied using the Freundlich relationship. Good agreement was found suggesting that sediment and humic/fulvic acids have an important role in the mobility, dispersion and sedimentation of metal ions in an aquatic environment. More of these heavy metals are removed in the pure system than in the natural system. This may be due to the lesser availability of humic and fulvic acids in the lagoons during the short detention time of sewage in suspension in the oxidation pond, whereas the sludge which has settled to the bottom of the pond for several years contains rich decomposed organic matter in the form of humic and fulvic acids containing heavy metals. Such pure systems could be useful for the effective removal of heavy metals.     

The influence of composting on the fertilizing value of an aerobic sewage sludge

The influence of composting on the fertilizing value of an aerobic sewage sludge and its action on ryegrass was studied. Soil P and K contents, cation-exchange capacity (CEC) and CEC/total organic carbon incresed with composting, while the percentage of phytotoxic substances diminished. The compost provided useful quantities of organic matter and macronutrients. The addition of uncomposted waste to the soil initially had a depressive effect on yield which disappeared after a period of incubation of this material in the soil, whereas the application of a mature compost produced yields superior to those in the control treatment.     

Sewage sludge addition to food waste synergistically enhances hydrogen fermentation performance

The effect of sewage sludge (SWS) addition on the H₂ fermentation of food waste (FW) was investigated. It was found that a slight addition of SWS (10:1 = FW:SWS on a COD basis) significantly enhanced the H₂ fermentation performance, not only increasing the total amount of H₂ produced but accelerating the whole reaction, shortening the lag period, and increasing the H₂ production rate. Substrate degradation and microbial germination were also facilitated by SWS addition. A simple calculation reveals that the increased amount of H₂ production derived mostly from FW, indicating that SWS addition synergistically enhanced H₂ fermentation performance. This was attributed to the existence of Fe and Ca at much higher concentrations in the SWS compared to the FW. The batch process treating a mixture of FW and SWS was repeated and showed an average H₂ yield of 2.11 ± 0.20 mol H₂/mol hexose_added, which was 13% higher than that of FW treated alone.     

利用餐厨垃圾循环半连续厌氧发酵产氢研究

利用餐厨垃圾采用半连续厌氧发酵进行产氢的研究。实验结果表明以高温(100℃)预处理15 min的厌氧活性污泥为种泥,在温度37℃,pH 6.0左右,较宽的稀释率(1.0~4.0 d-1)范围内,均能较好的实现厌氧发酵产氢。在稀释率D=2.4 d-1下,流出液中乙醇、乙酸、丙酸、丁酸和戊酸的质量分数分别为5.6%、29.6%、5.4%、58.5%和0.9%,产氢过程属于典型的丁酸型发酵,最终氢气的体积分数可达60%,氢气的产生速率为5.49 m3/(m3.d)。将厌氧发酵液相产物作为稀释液返回到反应器中,反应器的产氢能力大幅度的提高,当回流比R=0.8时,最大产氢速率可达10.9 m3/(m3.d),最终氢气的含量可达65%,厌氧发酵反应器的产氢能力提高了约130%。     

Isolation of a microbial consortium from activated sludge for the biological treatment of food waste

The bacterial community in the activated sludge of a local wastewater treatment plant was studied in an effort to understand and exploit the metabolic versatility of microorganisms for the efficient biological treatment of food waste. Microorganisms capable of and efficient in degrading domestic food waste were screened based on their ability to produce areas of clearing on selective media containing protein, fat, cellulose and starch. Nine microbial species belonging to the genera Flavobacterium, Pseudomonas, Micrococcus, Aeromonas, Xanthomonas, Vibrio and Sphingomonas were found to degrade all components of food waste. These bacteria were added to domestic wastewater and shown to cause a 60% reduction in the biochemical oxygen demand (BOD) level of wastewater compared to a control in which no microorganisms were added. The ability of the microbial consortium to degrade domestic wastewater as evidenced by the decrease in BOD levels suggests its potential for use in the biological treatment of food waste.     

Biomass adaptation over anaerobic co-digestion of sewage sludge and trapped grease waste

The feasibility of sewage sludge co-digestion using intermediate waste generated inside a wastewater treatment plant, i.e. trapped grease waste from the dissolved air flotation unit, has been assessed in a continuous stirred lab reactor operating at 35 °C with a hydraulic retention time of 20 days. Three different periods of co-digestion were carried out as the grease waste dose was increased. When the grease waste addition was 23% of the volatile solids fed (organic loading rate 3.0 kg_COD m⁻³ d⁻¹), an increase in methane yield of 138% was reported. Specific activity tests suggested that anaerobic biomass had adapted to the co-substrate. The adapted inoculum showed higher acetoclastic methanogenic and β-oxidation synthrophic acetogenic activities but lower hydrogenotrophic methanogenic activity. The results indicate that a slow increase in the grease waste dose could be a strategy that favours biomass acclimation to fat-rich co-substrate, increases long chain fatty acid degradation and reduces the latter’s inhibitory effect.     

Enzyme treatment to reduce solids and improve settling of sewage sludge

The effect of microbial enzymes in reducing the disposable solid content of sludge was investigated. A mixture of industrial cellulase, protease, and lipase, in equal proportion by weight, reduced total suspended solids (TSS) by 30–50% and improved settling of solids. An increase in solid reduction was observed with increasing enzyme concentration. The effect of combinations of enzyme treatments indicated that two-enzyme combinations of protease and cellulase produced better solid reduction than individual enzymes and that lipase further augmented this effect. Among the individual enzymes, protease produced a more settleable sludge as compared to cellulase and lipase. Adjustment of the pH of the enzymatically treated sludge to the acidic range (pH 2–4) further improved solid reduction, and adjustment to the alkaline range (pH 10–12) improved settleability. Journal of Industrial Microbiology & Biotechnology (2001) 26, 383–386. Received 01 November 2000/ Accepted in revised form 29 April 2001     

污泥蚯蚓粪对万寿菊生长发育的影响

以赤子爱胜蚓（Eisenia foetida）处理混合比例为1∶1、2∶1、3∶1、4∶1、5∶1和1∶0的污泥和牛粪得到污泥蚯蚓粪,并以10%、20%和30%（干物质量）与黑土混合,研究其对万寿菊株高、茎粗、叶片数、分枝数、地上部生物量、地下部生物量、根冠比、花蕾数、产花量、花直径和花生物量等生长发育指标的影响.结果表明：蚯蚓粪明显促进了万寿菊的生长发育;污泥和牛粪比值越小,对植物生长发育越有利;蚯蚓粪含量超过一定量,万寿菊生长发育状况有所下降,20%配比处理对万寿菊生长发育最为有利.     

学生食堂餐厨垃圾中淀粉的生物利用菌株筛选

目的探索地衣芽胞杆菌、枯草芽胞杆菌和蜡样芽胞杆菌分解大学生食堂厨余中淀粉的能力,以筛选和研制餐厨垃圾生物降解的使用菌种。方法将各菌种接于淀粉酶试验培养基,培养后滴加碘溶液,观察透明圈,判定产淀粉酶能力;收集大学生食堂的厨余,观察三种细菌在不同接种量（5%、10%、15%、20%、25%）、不同接种时间（24 h、48 h、72 h）及不同菌株配伍方式下发酵淀粉的能力。结果地衣芽胞杆菌、枯草芽胞杆菌、蜡样芽胞杆菌都能产生淀粉酶,以地衣芽胞杆菌产生的淀粉酶较多,其次为枯草芽胞杆菌,蜡样芽胞杆菌较少,三种细菌分解厨余中淀粉的最佳接种量都为15%-20%,最佳发酵时间为48 h,枯草芽胞杆菌和地衣芽胞杆菌各7.5%的接种量混合配伍发酵效果最佳。结论可采用枯草芽胞杆菌和地衣芽胞杆菌各7.5%的接种量混合配伍发酵学生食堂的厨余中的淀粉。     

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。     

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。     

几种花卉植物对污泥中铅的富集特征

土地利用是资源化利用城市污水厂污泥的有效途径。为了解污泥中重金属污染物在土壤、植物之间的迁移富集规律,选用8种园林用植物进行污泥混配土种植实验。结果表明,植物对污泥混配土土壤中铅的富集能力,以及铅在植物中各器官的富集系数均不同,且不同种类植物差别较大。植物根部对铅有较强的富集能力,其次是叶和茎。菊花对铅的富集能力较强。植物对土壤中铅的富集能力也受土壤铅含量和赋存形态影响。