Microbial Bioremediation and Different Bioreactors Designs Applied

Microbial remediation of pollutants involves the use of microorganisms to degrade pollutants either completely to water and carbon dioxide (for organic pollutants) or into less toxic forms. In the case of nonbiodegradable inorganic compounds, bioremediation takes the form of bioaccumulation or conversion of one toxic species to a less toxic form for example Cr(VI) is converted to less toxic (III). Bioremediation is considered an environmentally friendly way for pollution clean-up. Microbial clean up can be applied in situ (in place of contamination) or ex situ (off the site of contamination). In situ remediation in the natural environment is deemed slow and often times difficult to control and optimize the different parameters affecting the bioremediation. To this end, use of engineered bioreactors is preferred. Engineered bioreactors providing for optimum conditions for microbial growth and biodegradation have been developed for use in bioremediation processes to achieve the different desired remediation goals. Bioreactors in use range in mode of operation from batch, continuous, and fed batch bioreactors and are designed to optimize microbial processes in relationship to contaminated media and nature of pollutant. Designed bioreactors for bioremediation range from packed, stirred tanks, airlift, slurry phase, and partitioning phase reactors amongst others

Screening and evaluation of some green algal strains (Chlorophyceae) isolated from freshwater and soda lakes for biofuel production

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An assessment of the physicochemical properties and toxicity potential of carwash effluents from professional carwash outlets in Gauteng Province, South Africa

The assessment of the quality of carwash effluents has received scant attention as a potential source of public and environmental health hazard in South Africa as demonstrated by the lack of literature in this subject. The physicochemical quality and potential ramifications of carwash effluents on receiving waterbodies were investigated in this study. Grab effluent samples were collected from six carwash outlets in Gauteng Province of South Africa and analysed for selected physicochemical qualities including biological oxygen demand (BOD), oil and grease, total petroleum hydrocarbons-gasoline range organics (TPH-GRO), pH, dissolved oxygen (DO), total solids (TS) and total dissolved solids (TDS), electrical conductivity (EC), nutrients (nitrates, nitrites and phosphates), anionic surfactants and heavy metals (zinc [Zn], copper [Cu], lead [Pb] and chromium [Cr]). Further, the toxicity potential of the effluent samples was assessed using organisms from four trophic levels ranging from Selenastrum capricornutum (primary producer), Daphnia magna (primary consumer), Poecilia reticulata (secondary-tertiary consumer) and Vibrio fischeri (decomposer). High pollutant levels were observed in all effluents with BOD ranging from 27±2.1 to 650±4.9 mg/l, TDS from 362±8.5 to 686±8.5 mg/l, GRO-TPH from 0.01±0.0 to 7.6±0.2 mg/l, DO from 0.0 to 0.1 mg/l, Zn from 0.79±0.08 to 20±2.12 mg/l, Cu from 0.77±0.03 to 13±0.71 mg/l and oil and grease from 12±2.8 to 43±2.1 mg/l. Ammonium concentrations ranged from 0.4±0.1 to 75±6.4 mg/l; turbidity from 109±0.7 to 4000±29.7 mg/l, anionic surfactants from 1.4±0.1 to 5.8±0.3 mg/l and TPH from < 0.01 to 7.6 mg/l. Toxicity assessment assays resulted in 100% mortality for fish and Daphnia after 96 and 24 h respectively and significant bioluminescence and growth reduction in Vibrio fischeri and algae after 15 min and 72 h respectively. Most of the measured physicochemical parameters were in concentrations above the Environmental Management Agency (EPA) stipulated guidelines. Additionally, the effluents demonstrated acute toxicity against all four test species.UNISA-WiREnvironmental Science

Challenges and avenues for acid mine drainage treatment, beneficiation, and valorisation in circular economy: A review

Mining activities are notorious for their environmental impact, with acid mine drainage (AMD) being among the most significant issues. Specifically, AMD has recently been a topical issue of prime concern, primarily due to the magnitude of its environmental, ecotoxicological, and socioeconomic impacts. AMD originates from both active and abandoned mines (primarily gold and coal) and is encountered in Canada, China, Russia, South Africa, USA, and other countries with strong mining industry. Owing to its acidity, AMD contains elevated levels of dissolved (toxic) metals, metalloids, rare-earth elements, radionuclides, and sulfates. Practical and cost-effective solutions to prevent its formation are still pending, while for its treatment active (driven by frequent input of chemicals and energy) or passive (based on oxidation/reduction) technologies are typically employed with the first being more efficient in contaminants removal, however, at the expense of process complexity, cost, and materials and energy consumption. More recently, and under the circular economy concept, hybrid (combination of active and passive technologies) and particularly integrated (sequential or stepwise treatment) systems have been explored for AMD beneficiation and valorisation. These systems are costly to install and operate but are cleaner production systems since they can effectively prevent pollution and can be used for closed-loop and sustainable AMD management (e.g., zero liquid discharge (ZLD) systems). Herein, the body of knowledge on AMD treatment, beneficiation (metals/minerals recovery), valorisation (water reclamation), and life cycle assessment (LCA) is comprehensively reviewed and discussed, with focus placed on circular economy. Future research directions to introduce reuse, recycle, and resource recovery paradigms in wastewater treatment and to inspire innovation in valorising this toxic and hazardous effluent are also provided. Overall, AMD beneficiation and valorisation appears promising since the reclaimed water and the recovered minerals/metals could offset treatment costs and environmental impacts. However, the main challenges include high-cost, complexity, co-contamination in the recovered minerals, and the generation of a higly heterogeneous and mineralised sludge.</p

Pathogenicity and virulence factors of Escherichia coli discovered using next generation sequencing technologies and proteomics

Escherichia coli is a gastrointestinal bacterium previously known for its commensal activities in the human digestive systems. Their occurrence in drinking water and natural water sources has been used as a faecal pollution footprint or marker to determine the extent of pollution. However, their ability to cause diseases as an opportunistic bacterium is a global concern. Hence, unveiling their diverse virulence factors and pathogenicity through diverse technologies becomes pertinent. The advent of next-generation sequencing technologies and proteomics have significantly propelled these studies forward. Utilizing next-generation sequencing and proteomics, scientists have unveiled a multitude of pathogenicity and virulence factors linked to E. coli. This review underscores the advancements made in uncovering E. coli’s pathogenicity, virulence factors, and specific attributes through next-generation sequencing and selected proteomics investigations. The review presents and describes discovered pathogenicity and virulence factors. It concludes that while significant progress has been made, there is still much work to be done that can utilize next-generation sequencing and proteomics in this area of research fully. The in-depth study of E. coli’s virulence factors and pathogenicity could provide preventive/curative insight into a pattern or technologies that could be adopted to minimize the outbreak of disease associated with the bacterium even at their opportunistic level

Whole genome sequence of Serratia marcescens 39_H1, a potential hydrolytic and acidogenic strain.

Here, we report a high quality annotated draft genome of Serratia marcescens 39_H1, a Gram-negative facultative anaerobe that was isolated from an anaerobic digester. The strain exhibited hydrolytic/acidogenic properties by significantly improving methane production when used as a single isolate inoculum during anaerobic digestion of water hyacinth and cow dung. The total genome size of the isolate was 5,106,712 bp which corresponds to an N50 of 267,528 and G + C content of 59.7 %. Genome annotation with the NCBI Prokaryotic Genome Annotation Pipeline (PGAP) predicted a total of 4,908 genes of which 4,755 were protein coding genes; there were no plasmids detected. A number of genes associated with hydrolytic/acidogenic activities as well as other metabolic activities were identified and discussed

An evaluation of the bacterial diversity at Tshipise, Mphephu and Sagole hot water springs, Limpopo Province, South Africa

Tshipise, Mphephu and Sagole are thermal hot water springs in the Limpopo Province of South Africa with temperatures of 58, 43 and 45°C; and pH of 8.85, 8.08 and 9.70, respectively. The bacterial diversity of the hot water springs was determined by pyrosequencing of the two 16S rRNA hypervariable regions V1-3 and V4-7. Analyses of the community DNA revealed that bacterial populations as detectable by the V1-3 or V4-7 region, respectively were dominated by the Bacteriodetes and Proteobacteria for Mphephu, and Proteobacteria and Cyanobacteria for both Tshipise and Sagole. The major differences in the bacterial diversity between the springs was that no Cyanobacteria were detected for Mphephu and the level of Bacteriodetes detected for both Tshipise and Sagole was much lower compared to the levels detected at Mphephu. The Firmicutes were detected at all the springs but at a much lower abundance compared to the other main phyla detected. Various other phyla were detected at the hot springs at levels below 0.20% of the total sequences obtained. It is interesting that very diverse bacterial genera exist in the three hot water springs studied.This research was supported through a grant from Water Research Commission (WRC, SA, Project K5/1959/1).http://www.academicjournals.org/AJM