Va Jackson

Biodegradation of Free Cyanide Using Bacillus Sp. Consortium Dominated by Bacillus Safensis, Lichenformis and Tequilensis Strains: A Bioprocess Supported Solely with Whey

Several bacterial species (n=13) were isolated from electroplating wastewater to assess their ability to biodegrade free cyanide (F-CN). A mixed culture mainly dominated by Bacillus sp (Bacillus safensis, Bacillus lichenformis and Bacillus tequilensis) was cultured in nutrient broth for 48 hours at 37°C, to which F-CN as KCN (200 to 400 mg CN-/L) was added in order to evaluate the species ability to tolerate and biodegrade the cyanide. In nutrient broth, the microorganisms were able to degrade 131(65.5%) and 177 (44.3%) mg CN-/L in cultures containing 200 and 400 mg CN-/L over a period of 8 days, respectively. Subsequently, cultures were supplemented solely with agrowaste extracts, i.e. Ananas comosus extract (1% v/v), Beta vulgaris extract (1% v/v), Ipomea batatas extract (1% v/v), spent brewer’s yeast (1% v/v) and whey (0.5% w/v), as the primary carbon sources in 200 and 400 mg CN-/L cultures. The bacterial species were able to degrade F-CN in cultures that were supplemented with whey, whereby 179 (89.5%) and 239 (59.75%) mg CN-/L was biodegraded from 200 and 400 mg CN-/L cultures, respectively.

Bioremediation of polycyclic aromatic hydrocarbon (PAH) compounds: (acenaphthene and fluorene) in water using indigenous bacterial species isolated from the Diep and Plankenburg rivers, Western Cape, South Africa

This study was conducted to investigate the occurrence of PAH degrading microorganisms in two river systems in the Western Cape, South Africa and their ability to degrade two PAH compounds: acenaphthene and fluorene. A total of 19 bacterial isolates were obtained from the Diep and Plankenburg rivers among which four were identified as acenaphthene and fluorene degrading isolates. In simulated batch scale experiments, the optimum temperature for efficient degradation of both compounds was determined in a shaking incubator after 14 days, testing at 25 °C, 30 °C, 35 °C, 37 °C, 38 °C, 40 °C and 45 °C followed by experiments in a Stirred Tank Bioreactor using optimum temperature profiles from the batch experiment results. All experiments were run without the addition of supplements, bulking agents, biosurfactants or any other form of biostimulants. Results showed that Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila efficiently degraded both compounds at 37 °C, 37 °C, 30 °C and 35 °C respectively. The degradation of fluorene was more efficient and rapid compared to that of acenaphthene and degradation at Stirred Tank Bioreactor scale was more efficient for all treatments. Raoultella ornithinolytica, Serratia marcescens, Bacillus megaterium and Aeromonas hydrophila degraded a mean total of 98.60%, 95.70%, 90.20% and 99.90% acenaphthene, respectively and 99.90%, 97.90%, 98.40% and 99.50% fluorene, respectively. The PAH degrading microorganisms isolated during this study significantly reduced the concentrations of acenaphthene and fluorene and may be used on a larger, commercial scale to bioremediate PAH contaminated river systems.

Polycyclic Aromatic Hydrocarbons: A Critical Review of Environmental Occurrence and Bioremediation

The degree of polycyclic aromatic hydrocarbon contamination of environmental matrices has increased over the last several years due to increase in industrial activities. Interest has surrounded the occurrence and distribution of polycyclic aromatic hydrocarbons for many decades because they pose a serious threat to the health of humans and ecosystems. The importance of the need for sustainable abatement strategies to alleviate contamination therefore cannot be overemphasised, as daily human activities continue to create pollution from polycyclic aromatic hydrocarbons and impact the natural environment. Globally, attempts have been made to design treatment schemes for the remediation and restoration of contaminated sites. Several techniques and technologies have been proposed and tested over time, the majority of which have significant limitations. This has necessitated research into environmentally friendly and cost-effective clean-up techniques. Bioremediation is an appealing option that has been extensively researched and adopted as it has been proven to be relatively cost-effective, environmentally friendly and is publicly accepted. In this review, the physicochemical properties of some priority polycyclic aromatic hydrocarbons, as well as the pathways and mechanisms through which they enter the soil, river systems, drinking water, groundwater and food are succinctly examined. Their effects on human health, other living organisms, the aquatic ecosystem, as well as soil microbiota are also elucidated. The persistence and bioavailability of polycyclic aromatic hydrocarbons are discussed as well, as they are important factors that influence the rate, efficiency and overall success of remediation. Bioremediation (aerobic and anaerobic), use of biosurfactants and bioreactors, as well as the roles of biofilms in the biological treatment of polycyclic aromatic hydrocarbons are also explored.

Identification of point sources of metal pollution in the Berg River, Western Cape, South Africa

The aim of this study was to statistically compare sampling sites identified along the Berg River system to identify the major point sources of metal pollution from June 2004 to May 2005. Three sites were selected [site A—agricultural farming area, site B—Plot 8000 (close to the informal settlement), and site C—the Newton pumping station] representing different sectors which the river services. Aluminium (Al), iron (Fe), manganese (Mn), and lead (Pb) concentrations were determined using Inductively Coupled Plasma Atomic Emission Spectrometry and were statistically compared and analysed with one-way ANOVAs. For all the metals analysed, site C (industrial area) proved to be the site where the highest average metal concentrations were recorded. Generally, the concentrations recorded at site A (site furthest from the industrial area) were significantly (p < 0.05) lower than the concentrations recorded at both sites B and C. While the Al and Fe concentrations were consistently higher than any of the other metals analysed for, site C was identified as the primary source of metal contamination in the Berg River, resulting from the runoff from industrial activities at this particular site.

Investigation into the bacterial pollution levels at various sites along the Diep and Plankenburg river systems, 3 Western Cape, South Africa

This study sought to investigate and compare bacterial contamination levels at six different sites along the Diep and Plankenburg river systems in the Western Cape, South Africa. Surface water and sediment samples were collected monthly from the six selected sampling sites along both river courses between January 2014 and December 2014 and were evaluated for bacterial contaminants. Microbial isolation, characterisation and identification were done using conventional techniques (serial dilution, Gram staining, and biochemical testing) and molecular identification techniques (polymerase chain reaction and DNA sequencing). A total of 19 bacterial isolates belonging to the genera Raoultella, Bacillus, Pseudomonas, Klebsiella, Escherichia, Enterobacter, Exiguobacterium, Acinetobacter, Serratia, Aeromonas, Staphylococcus and Citrobacter were isolated from the surface water and sediment samples at the end of the survey. Higher microbial load was obtained from sediment samples compared to surface water samples. Seasonal variation was also observed in terms of microbial counts. Higher microbial counts were obtained during summer sampling time compared to winter sampling time. The most contaminated site was located on Plankenburg River with average bacterial counts ranging between 3.1 × 10(5)-6.9 × 10(8) CFU/ml and 3.9 × 10(6)-2.88 × 10(9) CFU/ml from surface water and sediment, respectively, recorded at this site during winter and summer. Although lower microbial counts were recorded along the Diep River course, most of the bacterial counts recorded along both rivers exceeded the acceptable maximum limits for river water.