Oghenerobor Benjamin Akpor

Nutrient removal from activated sludge mixed liquor by wastewater protozoa in a laboratory scale batch reactor

The aim of the study was to investigate the nutrient removal rate of three wastewater protozoan isolates. The study was carried out in a laboratory-scale batch reactor for a period of 120 h. in a four batch study. Aliquot samples were withdrawn from the reactor every 24 h. for the analysis of phosphate, nitrate, nitrite, ammonia, chemical oxygen demand, dissolved oxygen and pH, using standard methods. The results obtained in the different batches among the three isolates showed PO42− removal rate ranging from 0.04 to 0.52 mg-PO42−/L/h. while NO3− nitrate removal rates ranged from 0.08 to 0.16 mg-NO3−/L /h. Also NO2- and NH3 rates were observed to range between 0.022 and 0.087 mg-NO2−/L /h. 0.05 and 0.16 mg-NH3−/L /h, respectively. For the physicochemical parameters, there was no observed COD decrease; rather there was an increase and this was irrespective of isolates and experimental batches. However, dissolved oxygen concentration decreased drastically (below 1 mg/L) at the end of each batch while pH show a decrease after an initial 24 h. period and thereafter increased. This trend was also irrespective of isolates and experimental batches. Overall, the study has been able to show the effect of the test isolates on nutrient removal rates and other physicochemical parameters (COD, DO and pH) in activated sludge mixed liquor.

Relationship of protozoan biomass to phosphate and nitrate removal from activated sludge mixed liquor

The relationship between protozoan biomass concentration and phosphate and nitrate removal was investigated in mixed liquor using three different carbon sources as supplements. The study was carried out using three respective initial biomass concentrations in a shaking flask environment. Samples were taken every 24 h to determine phosphate, nitrate, dissolved oxygen and chemical oxygen demand. The results revealed a direct relationship between decreases in nutrient concentrations and increases in cell densities of the isolates. Between 24 and 96 h, the increases in the protozoan density corresponded to a phosphate decreases from initial ranges of 55.42–57.36 mg/L, 50.27–51.17 mg/L and 50.01–50.83 mg/L to final ranges of 2.46–11.90 mg/L, 0.61–11.80 mg/L and 1.29–13.89 mg/L, in the presence of Aspidisca, Trachelophyllum and Peranema, respectively. Nitrate concentrations were observed to decrease from initial ranges of 23.84–25.90 mg/L, 23.94–25.84 mg/L and 26.12–26.54 mg/L to final ranges of 0.11–6.32 mg/L, 0.16–5.60 mg/L and 0.24–9.04 mg/L, respectively. The study had revealed that an increase in cell density of the test isolates produces a corresponding increase in phosphate and nitrate removal.

Protozoan biomass relation to nutrient and chemical oxygen demand removal in activated sludge mixed liquor

The relationship between biomass concentration to nutrient and chemical oxygen demand (COD) removal in mixed liquor supplemented with sodium acetate was investigated, using three protozoan isolates and three different initial biomass concentrations (10(1), 10(2) and 10(3) cells/mL). The study was carried out in a shaking flask environment at a shaking speed of 100 rpm for 96 h at 25 degrees C. Aliquot samples were taken periodically for the determination of phosphate, nitrate, COD and dissolved oxygen, using standard methods. The results revealed remarkable phosphate removal of 82-95% at biomass concentration of 10(3)cells/mL. A high nitrate removal of over 87% was observed at all initial biomass concentration in mixed liquor. There was an observed COD increase of over 50% in mixed liquor in at the end of 96-h incubation and this was irrespective of initial biomass concentration used for inoculation. The study shows the trend in nutrient and COD removal at different biomass concentrations of the test isolates in mixed liquor.

Assessment of bacterial and fungal spoilage of some Nigerian fermented and unfermented foods

The study was aimed at evaluating the microbial spoilage of selected Nigerian fermented and unfermented foods. A total of four fermented and unfermented food samples were used for this investigation. Microbial and sensory evaluations of the food products during storage were carried out using standard procedures. During storage, the bacteria counts were observed to range from 2.2 × 105 to 4.8 × 105 CFU/mL and from 2.5 × 103 to 5.0 × 104 CFU/mL, for the unfermented and fermented food products, respectively. Similarly, the fungal counts ranged from 1.8 × 103 to 2.9 × 103 CFU/mL and from 0 to 5.70 × 103 CFU/mL for the unfermented and fermented food samples, respectively. Klebsiella aerogenes, Lactobacillus plantarum, Leuconostoc sp., Micrococcus varians, Proteus mirabilis, Streptococcus faecalis, Staphylococcus epidermidis, Aspergillus niger, Aspergillus flavus, Cladosporium herbarum, Geotrichum candidum, Mucor mucedo, Neurospora sitophilia and Penicillium sp. bacteria and fungi that were recovered from the food samples during storage. The sensory evaluation of the food products showed the fermented ones being more acceptable to panelists than the unfermented ones. This could indicate that the palatability of the fermented food samples only experienced slight or no changes during storage, when compared to the unfermented ones. n n Key words: Fermented food, unfermented food, microbial spoilage.

Investigation of the Role of Selected Fungal Strains in the Removal of Phosphate and Nitrate in Synthetic Wastewater

Aims: This study investigate the role of four fungi species in the removal of phosphate and nitrate in a low nutrient synthetic wastewater. Also investigated was the effect of initial inoculum size on the nutrient removal ability of the strains. nMaterials and Methods: The fungal strains used for the study were Aspergillus niger, Aspergillus flavus, Absidia spp and Fusarium spp Four different initial inoculum sizes of each of the respective isolates were used for the nutrient removal studies. After inoculation with the test strains, aliquot samples were taken from the media at time zero and every 24h, for the estimation of total phosphate, nitrate and pH in the medium, using standard methods. nResults: All the strains showed nitrate removal ability, irrespective of the initial inoculum size used for inoculation. After 96 h, the percent nitrate removed ranged from 25.25% to 77.52%, 26.12% to 39.80%, 8.88% to 44.23% and 29.50% to 87.34%, in the presence of Aspergillus niger, Aspergillus flavus, Absidia spp and Fusarium spp, respectively. None of the fungi exhibited phosphate removal ability, except Aspergillus niger which showed very slight potential for phosphate removal. Despite the observed differences in nitrate concentration removed by the different strains, these differences were not observed to ndiffer significantly between the initial inoculum sizes used for investigation (p≤ 0.05). Similarly, the phosphate concentrations in the presence of the test strains did not differ significantly between the different initial inoculum sizes (p≤ 0.05). The pH values of the wastewater inoculated with the fungal strains increased with time of incubation. This trend was also observed irrespective of the initial inoculum size used. nConclusion: The study was able to provide an insight into the phosphate and nitrate removal efficiency of the test strains under the experimental conditions. nKeywords: Phosphate; nitrate; fungi; nutrient removal; wastewater.

Effect of nitrogen source concentration on decolouration rates of laboratory dyes by immobilized cells of two bacterial species

The aim of this study was to assess the effect of sodium nitrate concentration on the decolouration of laboratory dyes (bromothymol blue, crystal violet, eosin blue, eosin yellow and methylene blue), by alginate immobilized cells of Pseudomonas aeruginosa and Bacillus subtilis. The sodium nitrate concentrations used in the study were 5, 10, 15 and 20xa0g/L. A control setup that contained no sodium nitrate was also studied. During incubation, aliquot samples were withdrawn from each flask every 24 for 144xa0h duration for the estimation of decolouration rate of the dyes, using standard procedures. The results revealed remarkable decolouration of the bromothymol blue and crystal violet in presence of the P. aeruginosa occurring at sodium nitrate concentrations of 10 and 15xa0g/L, respectively. In the case of media that was inoculated with the B. subtilis cells, although no remarkable decolouration of the bromothymol blue and crystal violet was observed throughout the period of incubation, highest decolouration were observed at sodium nitrate concentration of 5 and 10xa0g/L, respectively. For the eosin blue and methylene dyes, no remarkable decolouration were observed in presence of the test bacterial species at the respective sodium nitrate concentrations. Highest decolouration of the eosin yellow was however observed in media with sodium nitrate concentration of 5xa0g/L. The results of this study could be applied in scale up studies and continuous process, for implementation in biological decolouration of dye effluents.

Investigation of the Efficiency of Selected Bacterial and Fungal Species in the Removal of Phosphate and Sulphate from Wastewater

The aim of this study was to ascertain the efficiency of selected bacteria (Pseudomonas, Staphylococcus, Klebsiella and Lysinibacillus species) and fungi (Aspergillus niger, Aspergillus flavus, Fusarium and Absidia species) in the removal of phosphate and sulphate compounds from wastewater. The study was carried out under shaking flasks conditions. The test wastewater was filtered, sterilised and inoculated with the respective test bacterial and fungal isolates. Just after inoculation with a test isolate and every 24 h for 96 h, aliquot wastewater sample was taken from each flask aseptically for the estimation of phosphate and sulphate concentration in the wastewater. The results revealed remarkable phosphate and sulphate removal within the first 24 h and 48 h, respectively of incubation in the presence of three of the bacterial (Pseudomonas, Staphylococcus and Klebsiella) isolates, after which increases were observed. In the presence of the fungal isolates, remarkable decreases in phosphate and sulphate levels in the wastewater were observed after the first 48 h of incubation in the presence of the Aspergillus niger and Aspergillus flavus. In the presence of the Fusarium spp., there were Review Article Dahunsi et al.; JSRR, Article no. JSRR.2014.14.004 1876 consistent decreases in phosphate and sulphate levels with time. No remarkable decreases in phosphate and sulphate levels were observed with time in the presence of the Lysinibacillus and Absidia species. The study was able to give an insight into the phosphate and sulphate removal ability of the test isolates under the experimental conditions.

Effects of External Carbon Source Concentration on Sulphate Removal by Selected Bacterial and Fungal species

The aim of this study was to investigate the role of initial external carbon source concentration on sulphate removal by four bacterial and four fungal isolates under shake flask conditions. The test wastewater was filtered and supplemented with sodium acetate as the external carbon source at respective concentrations of 5g/L, 10g/L, 15g/L and 20g/L, before dispensing in 200mL quantity in 250mL capacity conical flasks, sterilised and inoculated with the test microbial isolates. Prior inoculation and at 24h interval, for 96 h for the estimation of sulphate concentration in the wastewater using standard methods. The results revealed remarkable sulphate removal in the absence of the sodium acetate and on its 5g/L addition. An increase in the concentration of the sodium acetate caused a corresponding decrease in the level of sulphate removal. Percentage sulphate removals in presence of the test isolates were observed to range from 47.01 to 57.81%, 18.66 to 51.66%, -1.64 to 11.03%, 5,38 to 22.37% and -3.59 to 5.18%, at sodium acetate concentrations of 0g/L, 5g/L, 10g/L, 15g/L and 20g/L, respectively. This trend was