Removal of hazardous metals through biological means has received considerable attention in the last few decades. Nevertheless, only a fraction of these studies employed growing microbial cells that harbor multiple mechanisms of metal sequestration and thus may hold greater metal uptake capacities. The authors summarize the studies concerning response of growing cells to metals toxicity in terms of growth rate, biomass production, and morphological/structural adaptations along with latest reports involving genomics and proteomics approach. The studies indicate bright potential of metal resistant strains or strains with hormesis phenomenon for field application. In the second part of the review they focuses on the effect of nutritional conditions and process parameters on metal removal capacities and the performance in simultaneous removal of multiple pollutants. Reports demonstrating effective treatment of actual industrial effluents using growing cells have been summarized. With ample evidence available ...

Recent Advances in Microbial Metal Bioaccumulation

Remediation of Cu, Pb, Zn and Cd-contaminated agricultural soil using a combined red mud and compost amendment

Trace metals contamination of rivers and sediments remains a global threat to biodiversity and humans. This study was carried out to assess the variation pattern in trace metals contamination in Mvudi River water and sediments for the period of January–June 2014. Metal concentrations were analyzed using an inductively-coupled plasma optical emission spectrometer after nitric acid digestion. A compliance study for the water samples was performed using the guidelines of the Department of Water Affairs and Forestry (DWAF) of South Africa and the World Health Organization (WHO). The National Oceanic and Atmospheric Administration (NOAA) sediment quality guidelines for marine and estuarine sediments and the Canadian Council of Ministers of the Environment sediment guidelines (CCME) for freshwater sediments were used to determine the possible toxic effects of the metals on aquatic organisms. pH (7.2–7.7) and conductivity (10.5–16.1 mS/m) values complied with DWAF and WHO standards for domestic water use. Turbidity values in nephelometric turbidity units (NTU) were in the range of 1.9–429 and exceeded the guideline values. The monthly average levels of trace metals in the water and sediments of Mvudi River were in the range of: Al (1.01–9.644 mg/L and 4296–5557 mg/kg), Cd (0.0003–0.002 mg/L and from below the detection limit to 2.19 mg/kg), Cr (0.015–0.357 mg/L and 44.23–149.52 mg/kg), Cu (0.024–0.185 mg/L and 13.22–1027 mg/kg), Fe (0.702–2.645 mg/L and 3840–6982 mg/kg), Mn (0.081–0.521 mg/L and 279–1638 mg/kg), Pb (0.002–0.042 mg/L and 1.775-4.157 mg/kg) and Zn (0.031–0.261 mg/L and 14.481–39.88 mg/kg). The average concentrations of Al, Cr, Fe, Mn and Pb in the water samples exceeded the recommended guidelines of DWAF and WHO for domestic water use. High concentrations of Al and Fe were determined in the sediment samples. Generally, the concentrations of Cd, Cr and Cu in the sediments exceeded the corresponding effect range low (ERL) values in the sediment quality guidelines and could have adverse effects on aquatic organisms in Mvudi River.

Assessment of Trace Metals Contamination of Surface Water and Sediment: A Case Study of Mvudi River, South Africa

Manganese removal during bench-scale biofiltration.

The harvesting of rainwater is gaining acceptance among many governmental authorities in countries such as Australia, Germany, and South Africa, among others. However, conflicting reports on the microbial quality of harvested rainwater have been published. To monitor the presence of potential pathogenic bacteria during high-rainfall periods, rainwater from 29 rainwater tanks was sampled on four occasions (during June and August 2012) in a sustainable housing project in Kleinmond, South Africa. This resulted in the collection of 116 harvested rainwater samples in total throughout the sampling period. The identities of the dominant, indigenous, presumptive pathogenic isolates obtained from the rainwater samples throughout the sampling period were confirmed through universal 16S rRNA PCR, and the results revealed that Pseudomonas (19% of samples) was the dominant genus isolated, followed by Aeromonas (16%), Klebsiella (11%), and Enterobacter (9%). PCR assays employing genus-specific primers also confirmed the presence of Aeromonas spp. (16%), Klebsiella spp. (47%), Legionella spp. (73%), Pseudomonas spp. (13%), Salmonella spp. (6%), Shigella spp. (27%), and Yersinia spp. (28%) in the harvested rainwater samples. In addition, on one sampling occasion, Giardia spp. were detected in 25% of the eight tank water samples analyzed. This study highlights the diverse array of pathogenic bacteria that persist in harvested rainwater during high-rainfall periods. The consumption of untreated harvested rainwater could thus pose a potential significant health threat to consumers, especially children and immunocompromised individuals, and it is recommended that harvested rainwater be treated for safe usage as an alternative water source.

Distribution of Indigenous Bacterial Pathogens and Potential Pathogens Associated with Roof-Harvested Rainwater

This study was aimed at investigating and comparing the microbial contamination levels at various sites in the Plankenburg and Diep Rivers in the Western Cape, South Africa. Sampling of sites along the Plankenburg River started in June 2004 and continued for a period of 1 year until June 2005. Sampling of the Diep River sites started in March 2005 and continued for a period of 9 months until November 2005. Faecal coliform (FC) and E. coli (EC) counts were determined by means of the most probable number (MPN) technique, the number of culturable cells were determined using the heterotrophic plate count (HPC) technique and total microbial counts were evaluated by Flow cytometric analysis (FCM). The highest microbial counts for the Plankenburg River were observed at Site B where the highest MPN, FC, E. coli and total FCM counts of 9.2 x 106 (Week 14), 3.5 x 106 (Week 39) and 3.5 x 106 micro-organisms/100 m. (Week 39) and 2.1 x 108 micro-organisms/m. (Weeks 1 and 39) respectively, were recorded. The highest HPC recorded for the Plankenburg River was 7.9 x 106 micro-organisms/100 m. (Week 44, Site A). Site B is situated close to an informal settlement where waste effluents from stormwater drainage pipes enter the river system. In addition, other possible contamination sources included agricultural (Site A) and industrial (Site C) areas bordering the Plankenburg River. The highest total MPN, FC and E. coli counts in the Diep River were 5.4 x 106 (Week 23) and 1.6 x 106 micro-organisms/100 m. (FC and E. coli, respectively (both in Week 23)), recorded at Site B. The highest HPC and total FCM counts of 1.7 x 107 micro-organisms/100 m. (Week 14) and 2.5 x 109 micro-organisms/m. (Week 23), respectively, were also recorded at Site B. This site was identified as the most contaminated site along the Diep River and served as an accumulation point for waste effluents from the residential and industrial areas, which included paint and machine manufacturers. Other sources situated along the Diep River included storage and maintenance facilities for steel containers, a wastewater treatment plant and an oil-refinery. Most of the bacterial counts obtained for the Plankenburg and Diep Rivers exceeded the accepted maximum limit for river water for most of the sampling period.

/pdf/comparison-of-microbial-contamination-at-various-sites-along-mcq3rpc28e.pdf

Comparison of microbial contamination at various sites along the Plankenburg: and Diep Rivers, Western Cape , South Africa

Metal contamination in the Plankenburg and Diep Rivers (Western Cape) was investigated over a 12 and 9 month period, respectively. Aluminium (Al), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn) concentrations were determined using the nitric acid digestion method and analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES). For both rivers the Al and Fe concentrations were higher than that for all the other metals analysed for in sediment and water samples. The highest concentrations recorded in the Plankenburg River were 13.6 mgE.-1 (water . Week 18, Site B) and 15 018 mgEkg-1 (sediment . Week 1, Site C) for Al, and 48 mgE.-1 (water . Week 43, Site A) and 14 363.8 mgEkg-1 (sediment . Week 1, Site A) for Fe. The highest concentrations recorded in the Diep River were 4 mgE.-1 (water . Week 1, Site A) and 19 179 mgEkg-1 (sediment . Week 1, Site C) for Al, and 513 mgE.-1 (water . Week 27, Site A) and 106 379.5 mgEkg-1 (sediment . Week 9, Site C) for Fe. For most of the metals analysed the concentrations were higher than the recommended water quality guidelines as stipulated by the Department of Water Affairs and Forestry, the Canadian Council for the Ministers of the Environment and the accepted eworld averagef. Point sources of pollution could not be conclusively identified, but runoff from both industrial and residential areas could have contributed to the increased concentrations. Metal concentrations should be routinely monitored and the guidelines should be updated and revised based on the current state of the rivers and pollution sources.

http://digitalknowledge.cput.ac.za/bitstream/11189/2632/3/Jackson_VA_Paulse_AN_Odendaal_JP_Khan_W_AppSci_2009.pdf

Investigation into the metal contamination of the Plankenburg and Diep Rivers, Western Cape

The study was aimed at assessing techniques, which would provide an accurate indication of the planktonic bacterial pollution load in the Berg River, Western Cape, South Africa Sampling of sites started in June 2004 and continued for a period of 1 year until June 2005 The most probable number (MPN) technique was used to determine the level of faecal coliforms and E coli, while the heterotrophic plate count method was used to determine the amount of culturable micro-organisms in planktonic samples The flow cytometry (FCM) and direct acridine orange count (DAOC) (epifluorescence microscopy) techniques were employed to evaluate total bacterial counts in planktonic (water) samples The highest MPN and heterotrophic plate counts were recorded in Week 37 at site B2 at 17 x 107 micro-organisms/100 m and 104 x 106micro- organisms/m, respectively In comparison, the viable FCM counts, were significantly higher (p < 005) for that period at 17 x 107 micro-organisms/m The highest total FCM count of 37 x 107 micro-organisms/m was recorded in Week 41 at Site B2 In comparison the highest DAOC of 83 x 106 micro-organisms/m was obtained in Week 29 at Site B2 Results showed that on average the heterotrophic plate count represented a fraction (< 365%) of the total FCM counts The total DAOC count also represented a fraction (< 4308%) of the total FCM count for most of the sampling period Results therefore showed that the FCM proved to be more effective in evaluating microbial pollution in water samples

https://www.ajol.info/index.php/wsa/article/viewFile/49055/35402

Comparison of enumeration techniques for the investigation of bacterial pollution in the Berg River, Western Cape, South Africa

http://digitalknowledge.cput.ac.za/bitstream/11189/2641/3/Jackson_VA_Paulse_AN_Bester_AA_Neethling_JH_Khan_S_Khan_W_AppSci_2009.pdf

Bioremediation of metal contamination in the Plankenburg River, Western Cape, South Africa

A recent decline in water quality of the Berg River, Western Cape, South Africa, has led to the investigation into the degree of metal pollution in the river system. This study was conducted over a period of one year, from May 2004 to May 2005. The nitric acid digestion technique was used to extract metals from water, sediment and biofilm samples collected at various points (Site A . agricultural area, Site B . informal settlement and Site C . Newton pumping station) along the Berg River. Metal concentrations were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). The highest mean metal concentrations recorded were as follows; water samples, 6 mgE.-1 for Al, 14.6 mgE.-1 for Fe and 18.8 mg..-1 for Mn; sediment samples, 17 448.8 mgEkg-1 for Al and 26 473.3 mgEkg-1 for Fe; biofilm samples, 876.8 mgE.-1 for Al and 1 017.5 mgE.-1 for Fe. The increased availability, or noteworthy incidence of Al and Fe, could be due to the leaching of metals into the river water from waste and household products associated with the informal settlement and the subsequent settling on sediment. No guidelines were available for metals in biofilms. The highest recorded concentrations in water were for Site C (agricultural area). Recorded concentrations in water fluctuated throughout the study period for most of the metals analysed, but Al and Fe were consistently above the recommended guidelines as stipulated by the Department of Water Affairs and Forestry and the Canadian Council of Ministers of the Environment.

/pdf/investigation-into-metal-contamination-of-the-berg-river-12aodvkeuv.pdf

A.N. Paulse

Papers

Comparison of microbial contamination at various sites along the Plankenburg: and Diep Rivers, Western Cape , South Africa

Investigation into the metal contamination of the Plankenburg and Diep Rivers, Western Cape

Comparison of enumeration techniques for the investigation of bacterial pollution in the Berg River, Western Cape, South Africa

Bioremediation of metal contamination in the Plankenburg River, Western Cape, South Africa

Investigation into metal contamination of the Berg River, Western Cape, South Africa