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3 Polish Journal of Environmental Studies

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Physicochemical properties of wastewater in three typical South African sewage works

100%

Agoro M. A. , Okoh O. O. , Adefisoye M. A. , Okoh A. I.

nr 2

The physicochemical qualities of the effluent samples of three municipal sewage treatment plants in the Eastern Cape of South Africa were evaluated from September 2015 to February 2016 using standard methods. The physicochemical parameters assessed include pH, temperature, total dissolved solid (TDS), turbidity, chemical oxygen demand (COD), alkalinity, dissolved oxygen (DO), free chlorine, chloride, sulphate, phosphate, ammonium, and electrical conductivity (EC). The results of the evaluation were as follows: temperature (19-36ºC), EC (60-1,095 mS/m), alkalinity (2.6-20.9 mg/L), nitrate (0.24-26.5 mg/L), nitrite (0.01-90 mg/L), phosphate (0.02-5.12 mg/L), ammonium (0.06-112 mg/L), sulphate (3-72 mg/L), chloride (3.25-224 mg/L), COD (17-394 mg/L), and turbidity (1.96-715 NTU). Free chlorine concentrations and DO were within the recommended limits for most of the sampling period and ranged between 0.17-0.48 mg/L and 0.19-21.9 mg/L, respectively. Also, the pH, phosphate, sulphate, and free chlorine concentrations were within acceptable limits, while EC, temperature, TDS, turbidity, COD, chloride, ammonium, nitrate, and nitrite did not conform to recommended limits. We conclude that these municipal sewage plants are sources of pollution to their respective receiving watersheds and threats to public and environmental health.

Molecular detection of metallo-beta-lactamase and putative virulence genes in environmental isolates of Pseudomonas species

100%

Igbinosa I. H. , Igbinosa E. O. , Okoh A. I.

nr 6

The aim of this study was to investigate the presence of metallo-β-lactamase (Imp-1, Vim-1, Vim-2) -resistant genes and putative virulence genes (ExoS, Apr, LasB, PhzM) in some environmental isolates of Pseudomonas species recovered from freshwater, wastewater, cultivated soil, plant root, and plant rhizosphere samples. Polymerase chain reaction (PCR) was employed to evaluate the presence and established metallo-β- lactamase and virulence genes using specific primer sets. About 6.7% of the Pseudomonas isolates from wastewater treatment plant were found to harbour the cytotoxin gene, while 20%, 20.6%, and 6.7% of the isolates were positive for alkaline protease, phenazine and Vim-2 genes, respectively. For the Pseudomonas species isolated from plant rhizosphere, 14.3% were positive for phenazine gene, while 10.7% were positive for Vim-2 gene. Dissemination of the target genes were in the following pattern: all isolates that harboured ExoS, Apr, and Vim-2 genes from wastewater sample were found to be Pseudomonas putida, while phenazine gene was found in 75% of Pseudomonas putida isolates and 25% of other Pseudomonas species. All plant rhizosphere isolates harbouring phenazine and Vim-2 genes were observed to be Pseudomonas putida species. The incidence of Vim-2 and virulence genes in some environmental isolates of Pseudomonas species suggest that these isolates are reservoirs of metallo-β-lactamase-resistant genes and are potential pathogens that may be of serious public health significance.

Studies on bioflocculant production by Bacillus sp. AEMREG7

88%

Okaiyeto K. , Nwodo U. U. , Okoli A. S. , Mabinya L. V. , Okoh A. I.

nr 1

The detrimental effects of inorganic and organic synthetic flocculants on humans and their recalcitrance in the environment have necessitated the search for safe, eco-friendly alternatives, including microbial flocculants. A bioflocculant-producing bacteria was isolated from sediment samples of Algoa Bay in the Eastern Cape Province of South Africa. The bacteria was identified through partial 16S ribosomal ribonucleic acids (rRNA), nucleotide sequencing, and BLAST analysis of the gene sequence that showed the bacteria to have 98% similarity to Bacillus algicola strain QD43 and deposited in GenBank as Bacillus sp. AEMREG7 with accession number KF933697.1. The effect of culture conditions on MBF-UFH production revealed optimally at inoculum size of 3% (v/v), glucose, a mixed nitrogen source [NH4 (SO4)2 + urea + yeast extract], and pH 6 for inoculums size, carbon and nitrogen sources, and initial medium pH for the fermentation process, respectively. The spent culture broth-rich bioflocculant attained the highest flocculating activity of 88.5% after 72 h of fermentation during the exponential phase of bacterial growth. It showed a high flocculating activity for kaolin clay suspension over a wide pH range of 4-10 with maximum flocculating activity observed at pH 6; and also retained 70.5% flocculating activity after heating at 100ºC for 60 min. These findings suggest that MBF-UFH has a great potential to substitute hazardous chemical flocculants commonly used in water treatment, hence reducing deformities among individuals in society.