The use of filter-feeding fish (Clarias gariepinus and Oreochromis mossambicus) to remove microalgae from brewery effluent treatment ponds
- Authors: Nombembe, Lwazi
- Date: 2019
- Subjects: Clarias gariepinus -- Food , Mozambique tilapia -- Food , Water -- Purification -- South Africa , Algae -- Biotechnology -- South Africa , Microalgae -- Biotechnology-- South Africa , Brewery waste -- South Africa , Fish culture -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95745 , vital:31194
- Description: The removal of microalgae from high rate algal ponds (HRAP) in waste-water treatment systems remains a constraint to their use in effluent treatment systems. Conventional algae harvesting methods often have high energy demands, take up lots of space, are expensive to operate or are time consuming. The aim of the study was to determine if fish such as Clarias gariepinus and Oreochromis mossambicus, could be used to remove microalgae from waste-water treatment ponds (in the absence/presence of a flocculent in the former and in the absence or presence of pH moderation in the latter), and to investigate the subsequent influence of algae concentration on several water quality parameters. The age of Clarias gariepinus (3-12 months) had a positive relationship with the distance between gill rakers (98.27 to 163.34 μm; y=90.576+4.823*x: R²=0.549; F(1,18)=21.867; p<0.001) and these data suggested that these fish might be efficient at removing algae from HRAP effluent. However, this was not the case, even with flocculent application (but this result might have been confounded by very high pH readings, at which flocculation is less likely to occur). Oreochromis mossambicus removed some of this algae, but the pH was too high for tilapia culture. It was not possible to moderate the increase in pH by keeping tanks in the dark and thus preventing photosynthesis; but pH fluctuation in HRAP effluent could be moderated using CO2 sparging in an attempt to make the environment more hospitable for tilapia (the average pH that was moderated with CO2 was 8.43±0.06, whereas the unmoderated average was 10.65±0.06). However, pH moderation using CO2 sparging did not increase the rate at which algae were removed by O. mossambicus; rather, it compromised O2 concentration which dropped to 4.17±1.26 mg/l after five hours of CO2 sparging, whereas it increased to 20.50±1.41 mg/l in treatments with unadjusted pH over the same period. Fish can be used to remove algae from treated effluent, and Oreochromis mossambicus remains a recommended species. Future work needs to investigate moderating fluctuations in pH and O2 concentration to further facilitate this method of algae removal.
- Full Text:
- Date Issued: 2019
- Authors: Nombembe, Lwazi
- Date: 2019
- Subjects: Clarias gariepinus -- Food , Mozambique tilapia -- Food , Water -- Purification -- South Africa , Algae -- Biotechnology -- South Africa , Microalgae -- Biotechnology-- South Africa , Brewery waste -- South Africa , Fish culture -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95745 , vital:31194
- Description: The removal of microalgae from high rate algal ponds (HRAP) in waste-water treatment systems remains a constraint to their use in effluent treatment systems. Conventional algae harvesting methods often have high energy demands, take up lots of space, are expensive to operate or are time consuming. The aim of the study was to determine if fish such as Clarias gariepinus and Oreochromis mossambicus, could be used to remove microalgae from waste-water treatment ponds (in the absence/presence of a flocculent in the former and in the absence or presence of pH moderation in the latter), and to investigate the subsequent influence of algae concentration on several water quality parameters. The age of Clarias gariepinus (3-12 months) had a positive relationship with the distance between gill rakers (98.27 to 163.34 μm; y=90.576+4.823*x: R²=0.549; F(1,18)=21.867; p<0.001) and these data suggested that these fish might be efficient at removing algae from HRAP effluent. However, this was not the case, even with flocculent application (but this result might have been confounded by very high pH readings, at which flocculation is less likely to occur). Oreochromis mossambicus removed some of this algae, but the pH was too high for tilapia culture. It was not possible to moderate the increase in pH by keeping tanks in the dark and thus preventing photosynthesis; but pH fluctuation in HRAP effluent could be moderated using CO2 sparging in an attempt to make the environment more hospitable for tilapia (the average pH that was moderated with CO2 was 8.43±0.06, whereas the unmoderated average was 10.65±0.06). However, pH moderation using CO2 sparging did not increase the rate at which algae were removed by O. mossambicus; rather, it compromised O2 concentration which dropped to 4.17±1.26 mg/l after five hours of CO2 sparging, whereas it increased to 20.50±1.41 mg/l in treatments with unadjusted pH over the same period. Fish can be used to remove algae from treated effluent, and Oreochromis mossambicus remains a recommended species. Future work needs to investigate moderating fluctuations in pH and O2 concentration to further facilitate this method of algae removal.
- Full Text:
- Date Issued: 2019
Treatment of anaerobically digested brewery effluent in high rate algal ponds: an understanding of the microbial community structure in the ponds and the underlying mechanisms responsible for nutrient removal from the effluent
- Authors: Mogane, Mmathabo Lucretia
- Date: 2017
- Subjects: Brewing industry -- Waste disposal -- South Africa , Breweries -- Waste displosal -- South Africa , Algae culture -- South Africa , Water -- Purification -- South Africa , Sewage lagoons -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5026 , vital:20754
- Full Text:
- Date Issued: 2017
- Authors: Mogane, Mmathabo Lucretia
- Date: 2017
- Subjects: Brewing industry -- Waste disposal -- South Africa , Breweries -- Waste displosal -- South Africa , Algae culture -- South Africa , Water -- Purification -- South Africa , Sewage lagoons -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5026 , vital:20754
- Full Text:
- Date Issued: 2017
The treatment of brewery effluent using an integrated high rate algal ponding system
- Authors: Cilliers, Anneke
- Date: 2012
- Subjects: Water -- Purification -- South Africa , Algae -- Biotechnology , Algae culture , Algae -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5331 , http://hdl.handle.net/10962/d1005177 , Water -- Purification -- South Africa , Algae -- Biotechnology , Algae culture , Algae -- Economic aspects
- Description: The application of high rate algal ponds (HRAP) in the treatment of brewery effluent that met the South African Department of Water Affairs and Forestry's (DWAF) general limits for discharge into a natural water resource of 1998 were tested during a lO-month baseline phase, followed by an 11-month optimization phase. The objective of the baseline phase was to monitor the seasonal performance of HRAPs. The hydraulic retention time (HRT) fluctuated between 11.16 d and 12.00 d in HRAPs. The chemical oxygen demand (COD) increased from 130.12 ± 6.94 mg/L (post-AD), to 171.21 ± 7.99 mg/L (post-HRAP) . The presence of algal cells and evaporation contributed towards an increase in post-HRAP COD. The ammonia (NH₄-N) concentration decreased from 46.59 ± 2.47 mg/L (post-AD), to 1.08 ± 0.12 mg/L (post-HRAP). The nitrite (NO₂- N) concentration remained below 1.00 mg/L in post-pilot plant AD, post-PFP and post-HRAP effluent. The phosphate (PO₄-P) concentration decreased from 29.81 ± 1.39 mg/L (post-AD) to 17.30 ± 1.16 mg/L PO₄-P. The objective of the optimization phase was to manipulate the HRT to achieve the maximum treatment rate that met the DWAF general limits for discharge into a natural water resource of 1998. Nitrogen (as NH₄-N, NO₃-N, NO₂-N) removal efficiency was used as an indicator of nutrient removal success. HRT was influenced by season. The optimal HRT for autumn was 4.30 d at a temperature of 20.53ºC in HRAP A2 (heated) and 18.96ºC in HRAP B2 (ambient). The optimal HRT for summer was 2.74 d at 29.90ºC in HRAP A2 (heated) and 26.36ºC in HRAP B2 (ambient). The COD decreased from 152.33 ± 4.85 mg/L (post-AD) to 95 .00 ± 3.75 mg/L (post-HRAP A2), and to 100.82 ± 5.93 mg/L (post-HRAP B2). The incoming NH₄-N concentration decreased from 42.53 ± 1.38 mg/ L (post-AD), to 1.70 ± 0.81 mg/ L (post-HRAP) . The nitrate (NO₃-N) concentration post-HRAP was 12 - 14 mg/L. The main methods for NH₄-N removal were probably NH₄-N volatilization through algal uptake. HRAPs were able to lower nitrogen and phosphorous concentrations to within the DWAF limits under normal operating conditions. It is recommended that HRAP treated brewery wastewater be used for irrigation after salt removal, or alternatively, for groundwater recharge . Regulatory exemptions would be required for higher than permitted COD and EC concentrations to enable these actions.
- Full Text:
- Date Issued: 2012
- Authors: Cilliers, Anneke
- Date: 2012
- Subjects: Water -- Purification -- South Africa , Algae -- Biotechnology , Algae culture , Algae -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5331 , http://hdl.handle.net/10962/d1005177 , Water -- Purification -- South Africa , Algae -- Biotechnology , Algae culture , Algae -- Economic aspects
- Description: The application of high rate algal ponds (HRAP) in the treatment of brewery effluent that met the South African Department of Water Affairs and Forestry's (DWAF) general limits for discharge into a natural water resource of 1998 were tested during a lO-month baseline phase, followed by an 11-month optimization phase. The objective of the baseline phase was to monitor the seasonal performance of HRAPs. The hydraulic retention time (HRT) fluctuated between 11.16 d and 12.00 d in HRAPs. The chemical oxygen demand (COD) increased from 130.12 ± 6.94 mg/L (post-AD), to 171.21 ± 7.99 mg/L (post-HRAP) . The presence of algal cells and evaporation contributed towards an increase in post-HRAP COD. The ammonia (NH₄-N) concentration decreased from 46.59 ± 2.47 mg/L (post-AD), to 1.08 ± 0.12 mg/L (post-HRAP). The nitrite (NO₂- N) concentration remained below 1.00 mg/L in post-pilot plant AD, post-PFP and post-HRAP effluent. The phosphate (PO₄-P) concentration decreased from 29.81 ± 1.39 mg/L (post-AD) to 17.30 ± 1.16 mg/L PO₄-P. The objective of the optimization phase was to manipulate the HRT to achieve the maximum treatment rate that met the DWAF general limits for discharge into a natural water resource of 1998. Nitrogen (as NH₄-N, NO₃-N, NO₂-N) removal efficiency was used as an indicator of nutrient removal success. HRT was influenced by season. The optimal HRT for autumn was 4.30 d at a temperature of 20.53ºC in HRAP A2 (heated) and 18.96ºC in HRAP B2 (ambient). The optimal HRT for summer was 2.74 d at 29.90ºC in HRAP A2 (heated) and 26.36ºC in HRAP B2 (ambient). The COD decreased from 152.33 ± 4.85 mg/L (post-AD) to 95 .00 ± 3.75 mg/L (post-HRAP A2), and to 100.82 ± 5.93 mg/L (post-HRAP B2). The incoming NH₄-N concentration decreased from 42.53 ± 1.38 mg/ L (post-AD), to 1.70 ± 0.81 mg/ L (post-HRAP) . The nitrate (NO₃-N) concentration post-HRAP was 12 - 14 mg/L. The main methods for NH₄-N removal were probably NH₄-N volatilization through algal uptake. HRAPs were able to lower nitrogen and phosphorous concentrations to within the DWAF limits under normal operating conditions. It is recommended that HRAP treated brewery wastewater be used for irrigation after salt removal, or alternatively, for groundwater recharge . Regulatory exemptions would be required for higher than permitted COD and EC concentrations to enable these actions.
- Full Text:
- Date Issued: 2012
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