Microbial diversity of Emalahleni mine water in South Africa and tolerance ability of the predominant organism to vanadium and nickel.

The present study aims firstly at determining the microbial diversity of mine-water collected in Emalahleni, South Africa and secondly isolating and characterizing the most dominant bacterial species found in the mine water in terms of its resistance to both V(5+) and Ni(2+) in a modified wastewater liquid media. The results revealed a microbial diversity of 17 orders, 27 families and 33 genera were found in the mine-water samples with Marinobacteria (47.02%) and Anabaena (17.66%) being the most abundant genera. Considering their abundance in the mine-water samples, a species of the Marinobacter genera was isolated, identified, and characterised for metal tolerance and removal ability. The MWI-1 isolate (Marinobacter sp. MWI-1 [AB793286]) was found to be closely related to Marinobacter goseongensis at 97% of similarity. The isolate was exposed to various concentrations of Ni(2+) and V(5+) in wastewater liquid media and its tolerance to metals was also assessed. The MWI-1 isolate could tolerate V(5+) and Ni(2+) separately at concentrations (in terms of MIC) up to 13.41 ± 0.56 mM and 5.39 ± 0.5 mM at pH 7, whereas at pH 3, the tolerance limit decrease to 11.45 ± 0.57 mM and 2.67 ± 0.1 mM, respectively. The removal of V(5+) and Ni(2+) in liquid media was noted to gradually decrease with a gradual increase of the test metals. A significant difference (p<0.05) between V(5+) and Ni(2+) removal was noted. Marinobacter sp. MWI-1 achieved the maximum permissible limit of 0.1 mg-V(5+)/L prescribed by UN-FAO at 100 mg/L, while at 200 mg/L only V(5+) was removed at approximately 95% and Ni(2+) at 47%. This study suggests that mine-water indigenous microorganisms are the best solution for the remediation of polluted mine water

Growth performance of MWI-1 in a medium containing either V⁵⁺ (A) or Ni²⁺ (B) or both (B) at 100 mg/L and 200 mg/L, 30°C, pH 7.2±0.2.

<p>Growth performance of MWI-1 in a medium containing either V⁵⁺ (A) or Ni²⁺ (B) or both (B) at 100 mg/L and 200 mg/L, 30°C, pH 7.2±0.2.</p

Phylogenetic tree using the neighbour-joining method, constructed and based on the bacterial 16S rRNA gene sequence detected in the present study along with similar sequences detected from the NCBI and RDP databases.

<p>Phylogenetic tree using the neighbour-joining method, constructed and based on the bacterial 16S rRNA gene sequence detected in the present study along with similar sequences detected from the NCBI and RDP databases.</p

Profile of mine water samples collected from the vanadium mine, South Africa (n = 3).

<p>Profile of mine water samples collected from the vanadium mine, South Africa (n = 3).</p

Summary of pyrosequencing data from mine water samples.

<p>Summary of pyrosequencing data from mine water samples.</p

MWI-1 isolate tolerance limits (MIC and 24 h LC₅₀) to V⁵⁺ and Ni²⁺, and removal ability in the modified liquid media (n = 5).

<p>MWI-1 isolate tolerance limits (MIC and 24 h LC₅₀) to V⁵⁺ and Ni²⁺, and removal ability in the modified liquid media (n = 5).</p

Relative abundance and diversity of bacterial phylum and classes in South African mine water.

<p>Relative abundance and diversity of bacterial phylum and classes in South African mine water.</p

Growth curve of MWI-1 in a metal-free medium (HMC broth) inoculated at different temperatures (25°C, 30°C, 35°C) at pH 7.2±0.2 for 24 h.

<p>Growth curve of MWI-1 in a metal-free medium (HMC broth) inoculated at different temperatures (25°C, 30°C, 35°C) at pH 7.2±0.2 for 24 h.</p

Composition of the bacterial orders, family and genera detected in the mine water with sequences of the variable region V1–3 of the 16S rRNA genes.

<p>Composition of the bacterial orders, family and genera detected in the mine water with sequences of the variable region V1–3 of the 16S rRNA genes.</p

Non-Metropolitan Drinking Water Suppliers’ Response to the Diagnostic Tool for Non-Technical Compliance in Limpopo, South Africa

Without the planning of non-technical issues, water treatment plants may face challenges in sustaining safe drinking water. Parameters such as the planning of financial resources, human resources, a lack of professional process controllers, poor working conditions, staff shortages and a lack of appropriate training of process controllers contribute to the underperformance of drinking water treatment plants. This study aimed at applying the Diagnostic Tool for Non-Technical Compliance to assess the compliance of small drinking water plants with management norms. Six water treatments (Vondo water scheme, Malamulele, Mutshedzi, Mutale regional water treatment plant, Tshedza and Tshedza package plant) were selected from the Vhembe district municipality of the Limpopo province in South Africa. From the abovementioned non-technical parameters, the results showed that during the first assessment period (August 2008 and June 2009) selected water treatment plants scored between 53% and 68% and fell under Class 2, indicating serious challenges requiring attention and improvement. During the second assessment period (November and December 2010), a slight improvement was observed as all plants scored between 72% and 80%, falling under the Class 2 category. Even after corrective actions and remeasurement, none of the plants met the compliance standards, which range from 90% to 100% to obtain the Class 1 compliance standard. The study recommended that tactical and strategic plans that clearly define the operational procedures, process controlling, financial planning, maintenance culture, emergency preparedness and regular monitoring and evaluation should be entrenched for the smooth running of the small water treatment plants. Furthermore, all water services providers and water services authorities should apply the diagnostic tools as developed, which provides guidance on a stepwise procedure on plant operations and management on a daily basis