Biosolids accumulation and biodegradation of domestic wastewater treatment plant sludge by developed liquid state bioconversion process using a batch fermenter

The biosolids accumulation and biodegradation of domestic wastewater treatment plant (DWTP) sludge by filamentous fungi have been investigated in a batch fermenter. The filamentous fungi Aspergillus niger and Penicillium corylophilum isolated from wastewater and DWTP sludge was used to evaluate the treatment performance. The optimized mixed inoculum (A. niger and P. corylophilum) and developed process conditions (co-substrate and its concentration, temperature, initial pH, inoculum size, and aeration and agitation rate) were incorporated to accelerate the DWTP sludge treatment process. The results showed that microbial treatment of higher strength of DWTP sludge (4% w/w of TSS) was highly influenced by the liquid state bioconversion (LSB) process. In developed bioconversion processes, 93.8 g/kg of biosolids was enriched with fungal biomass protein of 30 g/kg. Enrichment of nutrients such as nitrogen (N), phosphorous (P), potassium (K) in biosolids was recorded in 6.2% (w/w), 3.1% (w/w) and 0.15% (w/w) from its initial values of 4.8% (w/w), 2.0% (w/w) and 0.08% (w/w) respectively after 10 days of fungal treatment. The biodegradation results revealed that 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of COD in treated DWTP sludge supernatant were removed after 8 days of microbial treatment. The specific resistance to filtration (SRF) in treated sludge (1.4x10(12) m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation compared to untreated sample (85x10(12) m/kg).     

筒状单室不锈钢电极微生物燃料电池回收重金属铅可行性分析

以筒状单室不锈钢电极微生物燃料电池(MFC)为对象,研究了去除其其中铅的可行性. 结果表明,在批式条件下,当初始Pb2+浓度为40 mg/L、pH为4.0时,Pb2+去除速度和效率分别达0.53±0.06 mg/(L?h)和96.71%±1.35%,最终以碱式碳酸铅的形式回收Pb2+. Pb2+去除过程中首先在MFC作用下还原成单质铅,再因暴露在空气中转化为碱式碳酸铅,但该MFC的电化学性能相对较低,输出电压、功率密度和库仑效率只有30.62±1.04 mV, 8.20±0.24 mW/m2和5.92%±0.21%.     

Activated Chemical Defense in Aplysina Sponges Revisited

Sponges of the genus Aplysina accumulate brominated isoxazoline alkaloids in concentrations that sometimes exceed 10% of their dry weight. We previously reported a decrease in concentrations of these compounds and a concomitant increase in concentrations of the monocyclic nitrogenous compounds aeroplysinin-1 and dienone in Aplysina aerophoba following injury of the sponge tissue. Further investigations indicated a wound-induced enzymatic cleavage of the former compounds into the latter, and demonstrated that these reactions also occur in other Aplysina sponges. A recent study on Caribbean Aplysina species, however, introduced doubt regarding the presence of a wound-induced bioconversion in sponges of this genus. This discrepancy motivated us to reinvestigate carefully the fate of brominated alkaloids in A. aerophoba and in other Aplysina sponges following mechanical injury. As a result of this study we conclude that (1) tissue damage induces a bioconversion of isoxazoline alkaloids into aeroplysinin-1 and dienone in Aplysina sponges, (2) this reaction is likely catalyzed by enzymes, and (3) it may be ecologically relevant as the bioconversion products possibly protect the wounded sponge tissue from invasion of bacterial pathogens.     

The significance of chemical markers in the bioprocessing of fossil fuels

Biochemical conversion of crude oils is a multi-step process proceeding through a series of biochemical reactions. These reactions can be characterized by a set of chemical markers which are associated with the chemical composition of crude oils. Reactions with heavy crude oils indicate that there is an overall decrease in the concentration and chemical speciation of organic sulfur compounds, and a redistribution of hydrocarbons and organometallic species. The contents of trace metals in the crude oils, such as nickel and vanadium, also decrease. Further, heavy ends of crudes, containing the asphaltenes and the polar nitrogen, sulfur, and oxygen containing fractions, as well as the organometallic compounds and complexes, are biochemically converted to lower molecular weight chemical species. In the studies reported in this paper, microorganisms used to mediate such reactions were thermophilic ( > 60°C) and pressure tolerant (up to 2500 psi). These organisms are also capable of biochemical conversion of bituminous and lignite coals in an analogous manner to their action on crude oils and follow similar trends characterized by chemical markers. For example, X-ray absorption near-edge structural (XANES) analyses of biotreated crude oils and low grade coals show that biochemical reactions lead to decreases in organic sulfides and thiophenes with a concurrent increase in sulfoxide contents. Chemically related constituents present in heavy crude oil fractions and low grade coals are the asphaltenes. Asphaltenes are complex structures containing heteroatoms and metals involved in inter- and intra-molecular bridges and stereochemical configurations. The chemical markers associated with the biochemical conversion of oils and coals indicate multiple biochemical processes involving chemical reactions at sites containing heteroatoms and metals leading to a breakdown of the structure(s) to smaller molecular weight units. Thus, using chemical markers as diagnostic tools, the extent and the efficiency of fossil fuel bioconversion may be predicted and monitored, allowing for better cost-efficient field trials. Recent results in this area will be presented and discussed in this paper.     

Bioconversion of hydrocortisone to prednisolone by immobilized bacterial cells in a two-liquid-phase system

Bioconversion of hydrocortisone to prednisolone by free, immobilized and reused immobilized cells of three bacterial strains (Bacillus sphaericus ATCC 13805, Bacillus sphaericus SRP III and Arthrobacter simplex 6946) in an aqueous and a two-liquid-phase system using different organic solvents was investigated. The experiments were carried out in a 125 cm³ shake flask at 27±2°C, 220 rpm for 96 h. The contents of prednisolone and hydrocortisone in samples taken at 0, 3, 6, 24, 48, 72, 96 and 144 h were determined by HPLC analysis. The immobilized bacterial cells showed higher prednisolone yield than the free form in an aqueous system. In the two-phase systems, the butyl acetate to aqueous media ratio of 1: 30 for all three bacterial strains in immobilized forms gave the highest prednisolone yields, at an incubation time of 144 h, of 87·6, 70·6 and 88·3% respectively. For an n-decane to aqueous ratio of 1: 6, moderate prednisolone yields of 81·8, 47·9 and 71·4% were obtained with shorter incubation times of 72, 96 and 6 h respectively. For cyclohexane and other alcohols, the organisms produced low yields of prednisolone (0–30%). Single reuse of all three immobilized bacterial cells gave a 3–20% lower yield of prednisolone than the non-reused cells. The increase in hydrocortisone concentration decreased the prednisolone production whereas increasing the n-decane to aqueous ratio from 1: 6 to 1: 3 caused no significant change in the productivity. © 1998 Society of Chemical Industry     

Biotechnology for the conversion of lignocellulosics

During the last three years most of the research on bioconversion of lignocellulosics has focussed on a process scheme where the substrate is first pretreated, usually by high pressure steam, prior to fractionation into its cellulose, hemicellulose and lignin components. The cellulosic rich fraction is then hydrolyzed enzymatically, followed by fermentation of the liberated sugars to ethanol, while the lignin and pentose sugar rich streams are treated separately. The progress in each of these areas is discussed. Round robin activities between the participating labs were used to provide more uniform methods of quantifying cellulase and xylanase enzyme activities. The various technoeconomic models developed by network members were used to identify probable process schemes and determine technical “bottlenecks”. We could also identify which components of the process were the most cost-intensive and determine the levels at which further increases in yields and productivity would have little effect on the cost of the final product.     

Production of vitamins,coenzymes and related biochemicals by biotechnological processes

Vitamins and related biofactors belong to those few chemicals with a direct positive appeal to people. There is indeed a large need for extra vitamins, other than those derived from plant and animal food sources, due to unbalanced food habits or processing, food shortage or disease. Added vitamins are now either prepared chemically or biotechnologically via fermentation or bioconversion processes. Several vitamins and related biofactors are now only or mainly produced chemically (vitamin A, cholecalciferol (D₃), tocopherol (E), vitamin K₂, thiamine (B₁), niacin (PP or B₃), pantothenic acid (B₅), pyridoxine (B₆), biotin (H or B₈), folic acid (B₉) or via extraction processes (β-carotene or provitamin A, provitamin D₃, tocopherol, vitamin F-group). However, for several of these compounds microbiological or algal methods also exist or are rapidly emerging. Others are produced practically exclusively via fermentation (ergosterol or provitamin D₂, riboflavin (B₂), cyanocobalamin (B₁₂), orotic acid (B₁₃), vitamin F-group, ATP, nucleosides, coenzymes, etc. or via microalgal culture (β-carotene, E, F). Both chemical and microbial processes are run industrially for vitamin B₂ while vitamin C (ascorbic acid) is produced via a combination of chemical reactions and fermentation processes. A survey is given here of the current state of vitamin production, with emphasis on developments and strategies for improved biotechnological production and its significance, as compared to existing chemical processes. The screening or construction of vitamin hyperproducing microbial strains is a difficult task; pathway elucidation and metabolic (de)regulation need further study; r-DNA technology has only recently been introduced; improved fermentation processes and immobilised biocatalysts bioconversions for the synthesis of chiral vitamin compounds or intermediates or derivatives are gaining importance; the recovery and purification of these vitamin compounds from their fermentation broths remains equally complex.     

Biological conversion of coal and coal-derived synthesis gas

Recent research has resulted in a number of promising biological pathways to produce clean fuels from coal. These processes all involve two or more steps: either the biosolubilization of coal, followed by bioconversion to ethanol or methane; or conversion of coal to synthesis gas, followed by bioconversion into alcohols or methane. Sulfur may also be removed from the solubilized coal or synthesis gas in a separate, or concurrent, biological step. This paper presents research results from both the direct and indirect conversion of coal to liquid fuels using biological processes. A review of direct conversion techniques in producing liquid fuels from coal in a serial conversion process is presented. In addition, bioreactor design data for the conversion of CO, CO₂ and H₂ in synthesis gas by Clostridium ljungdahlii in both batch and continuous culture are reviewed and discussed.     

生物质能源转化技术与应用(Ⅷ)——生物质的生物转化技术原理与应用

生物质能源是惟一可再生、可替代化石资源转化成气态、液体和固态燃料以及其他化工原料或者产品的碳资源。随着化石资源的枯竭和人类对全球性环境问题的关注,生物质能源替代化石资源利用的研究和开发,已成为国内外众多学者研究和关注的热点。本系列讲座主要讲述以生物质资源为主要原料,通过不同途径转化为洁净的、高品位的气体、液体或固体燃料。本讲主要综述了木质纤维素的生物转化过程的关键技术,包括原料预处理、纤维素酶解、微生物发酵和产品的分离提纯,指出生物转化技术的发展趋势是非粮生物质的生物转化和利用,关键酶的改进和微生物代谢的调控以及生产过程的集成和产品的综合利用,并说明积极开展生物质产品的能效评价将有助于提高生物质能转换的经济效益。