Investigation of brewery waste grains and microbial fuel cells as value-additive technologies improving solvent production yields in Clostridium acetobutylicum (ATCC 824) fermentation
- Authors: Du Toit, Ryan Guillaume
- Date: 2023-10-13
- Subjects: Biomass energy , Butanol , Fermentation , Microbial fuel cells , Brewery waste , Clostridium acetobutylicum
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424643 , vital:72171
- Description: The production of the solvent compounds acetone, ethanol and butanol through fermentation of organic feedstocks using Clostridia species could be a promising route for biofuel production. However, the cost of raw materials, low yields and the complexity of anaerobic fermentation continue to hinder this means of generating these compounds. The research presented in this Thesis investigated low-cost interventions that could decrease the costs of production and to direct the synthesis of fuel compounds using microbial fuel cells. Low-cost anaerobic chambers were designed and constructed for the propagation and manipulation of Clostridium acetobutylicum, selected as a low-risk microbial catalyst. Fermentation was monitored using in situ pH measurements and a combination of turbidity measurements, nutrient assays (especially total carbohydrates) and HPLC-RI detection as a means of monitoring the consumption of nutrients (glucose), production of precursor compounds (butyric acid) and the formation of solvent molecules (acetone/ethanol and butanol) during fermentation by this organism. Brewer’s spent grains were tested as a sustainable and low-cost feedstock for solvent production, comparing the effects of sterilising before fermentation, or allowing resident microflora to remain during Clostridium-catalysed solvent production. Sterilised spent grains significantly improved the production of solvent molecules (e.g. 12.97 ± 0.38 g/L of butanol yielded, compared to 0.40 ± 0.33 g/L for defined media sampled during the solventogenic phase); compared to these, the use of non-sterilised brewer’s grain decreased both the reproducibility and yields of fermentation (8.66 ± 1.6 g/L of butanol). Microbial fuel cells were studied as a possible means of altering electron transfer to/from electrode-attached Clostridia to control the metabolic shift in bacteria from acidogenesis to solventogenesis. The base line MFC (11.00 ± 4.69 g/L) fermentation experiment did produce higher acetone/ethanol than the baseline batch experiment MB (5.47 ± 4.48 g/L), indicating an improvement to solvent production in C. acetobutylicum (ATCC 824) in a MFC fermentation. In this study, MFC-1 demonstrated remarkable superiority over MB in terms of butyric acid production, yielding significantly higher concentrations while also improving acetone and ethanol production. However, the enhanced butyric acid production did not correspond to significantly increased butanol yields when compared to batch fermentation of chemically defined media. These findings highlight the potential of MFC-1 as an efficient approach for enhancing the fermentative production of valuable compounds, with a particular focus on butyric acid and acetone/ethanol. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2023
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- Date Issued: 2023-10-13
Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
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- Date Issued: 2020
The integration of effluent treatment using constructed wetlands, with crop production and aquaculture
- Authors: de Jong, Martyn
- Date: 2019
- Subjects: Recycling (Waste, etc.) , Brewery waste , Sewage -- Purification , Beets , Mozambique tilapia
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95767 , vital:31197
- Description: Breweries are major consumers of water and produce nutrient rich wastewater. Therefore, it is important to research technologies that optimise the reuse and recycling of this waste. This study compared different constructed wetlands (CWs) in terms of their potential for cleaning brewery effluent and simultaneously producing crops Beta vulgaris and fish Oreochromis mossambicus. Filling and draining times (FDT; 15 min, 30 min and 60 min) in tidal CWs were compared in Experiment 1. The 15 min FDT (6.52 ± 0.09 mg/l) and 30 min FDT (5.74 ± 0.09 mg/l) had higher dissolved oxygen (DO) than the 60 min FDT (5.40 ± 0.09 mg/l; p<0.05). This resulted in the 15 and 30 min FDT treatments reaching ammonia effluent discharge standards sooner than the 60 min FDT. Total plant harvest increased with increasing FDT; therefore, 15 min FDT was used as the FDT in tidal treatments in the following experiments. The aerated CW (5.81 ± 0.07 mg/l) and tidal CW (5.67 ± 0.07 mg/l) treatments had higher DO concentrations than the unaerated CW treatment (3.76 ± 0.07 mg/l; p<0.05) in Experiment 2. This resulted in lower ammonia concentrations on day 5 in the aerated and tidal CWs compared with the unaerated treatment (p<0.05). The tidal CW (23.97 ± 2.57 kg) had a total harvest that was approximately four times higher than the unaerated CW (p<0.05), which had the highest frequency of chlorosis and plant mortality; and was unable to treat ammonia to discharge standards. In Experiment 3, the aerated and tidal CW were compared with municipal-water as water sources for aquaculture. There were no differences in fish growth (p > 0.05). However, there were differences in water quality; with the municipal treatment having the lowest pH, EC and nitrate concentration (p<0.05); but all water quality parameters remained in a range suitably for fish production. Due to the tidal CW having the highest plant harvest and lowest frequency of chlorosis and mortality; it was the most suitable CW technology to clean the brewery effluent, and to produce B. vulgaris and water that could be used downstream in aquaculture.
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- Date Issued: 2019
The water and nutrient potential of brewery effluent for hydroponic tomato production
- Authors: Power, Sean Duncan
- Date: 2014
- Subjects: Hydroponics , Tomatoes -- Breeding , Brewery waste , Water -- Purification , Algae culture , Algae -- Biotechnology , Nitric acid , Phosphoric acid
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5358 , http://hdl.handle.net/10962/d1011604 , Hydroponics , Tomatoes -- Breeding , Brewery waste , Water -- Purification , Algae culture , Algae -- Biotechnology , Nitric acid , Phosphoric acid
- Description: Brewery effluent that had undergone treatment in an anaerobic digester (AD) was used as an alternative water and nutrient source for hydroponic crop production. Brewery effluent was demonstrated to contain sufficient nutrients to support the growth, flowering and fruiting of Lycopersicum escolentum "Moneymaker" tomato crops. The adjustment of the effluent pH with phosphoric acid to between pH 6.0 and 6.5 increased the development of the crops by around 100% compared to crops grown in unaltered effluent. The pH adjusted effluent-grown plants grew to a mean height of 831.4 ± 21.1 mm and a dry biomass weight of 42.34 ± 2.76 g compared to the unaltered pH effluent plants which grew to a height of 410.6 ± 20.5 mm and a weight of 7.65 ± 0.68 g after 49 days. Effluent treatment in high-rate algal ponds (HRAP) was determined to have no positive effect on the nutritional potential of the effluent for Moneymaker production. The effluent-grown plants did not perform as well as plants grown in inorganic-fertilizer and municipal water. Plants grown in effluent grew taller but did not produce significantly more fruit when phosphoric acid (height: 1573.3 ± 50.4 mm, 19.4 ± 1.4 fruit per plant) was compared to nitric acid (height: 1254.1 ± 25.4 mm, 15.6 ± 1.5 fruit per plant) as the pH adjustment over 72 days. Direct and secondary plant stresses from effluent alkalinity, ammonium nutrition, nitrogen limitation, sodium concentrations and heat stress among other factors were probably confounding variables in these trials and require further investigation. Considering the raw effluent composition and manipulating the AD operation is a potential opportunity to improve overall AD performance, reduce chemical inputs in the effluent treatment process, reduce the final effluent alkalinity, and increase available nitrogen content in the final effluent. The anaerobic digester discharging >1000 m³ of nutrient enriched effluent every day is a resource with considerable potential. The benefits of developing this resource can contribute to cost-reduction at the brewery, more efficient water, nutrient and energy management at the brewery, and offer opportunities for job creation and potentially benefit local food security.
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- Date Issued: 2014