Nutrient removal and biofuel potential of MaB-floc biomass from an integrated algal pond system treating domestic sewage

  • Authors: Sibelo, Linda
  • Date: 2020
  • Subjects: Biomass energy , Waste products as fuel , Algal biofuels , Sewage -- Purification -- Nutrient removal
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/144955 , vital:38395
  • Description: Integrated algal pond systems (IAPS) are a passive water treatment technology derived from the Oswald designed advanced integrated wastewater pond systems (AIWPS®) and effect wastewater treatment based on biological activity of microorganisms within the system, solar energy and gravity. The technology consists of an advanced facultative pond (AFP), a series of interconnected high rate algal oxidation ponds (HRAOP) and algal settling ponds. The symbiotic relationship between microalgae and bacteria facilitated by paddlewheel mixing of HRAOP results in the formation of biomass aggregates known as MaB-flocs. MaB-floc formation enhances nutrient abstraction, gravitational sedimentation and separation from water hence forming two product streams; recyclable water and biomass, both with valorisation potential. This work aimed to determine the suitability of MaB-floc biomass generated in the HRAOP of an IAPS treating domestic sewage as feedstock for biofuel production based on the content of carbohydrate and lipid. Nutrient removal efficiency, biomass productivity and bulk lipid and carbohydrate concentration were monitored for two consecutive three-month periods in the winter and summer seasons of 2018/19. Maximum removal efficiencies of nitrogen and phosphorus were determined as 71% and 75% respectively, demonstrating the efficiency of IAPS as a wastewater treatment technology. MaB-floc biomass productivity in winter and summer was 9.4 g/m2/d and 16.5 g/m2/d respectively indicating the heavy influence of seasonal temperature, possibly day length, and solar irradiation on biomass productivity in the HRAOP. Summer productivity was lower than the maximum theoretical productivity of 25 g/m2/d possibly due to photoinhibition of photosynthesis as well as grazing pressures caused by the proliferation of rotifers mainly of the Brachionus genus. MaB-floc biomass consistently contained higher amounts of carbohydrate than lipid despite the changes in species dominance from Scenedesmus sp. and Desmodesmus sp. in winter to Pediastrum sp. in summer. Variations in MaB-floc biomass carbohydrate content were linked to changes in nitrogen concentration, mainly in the form of nitrates. Lower nitrogen concentration significantly increased the carbohydrate content of MaB-floc biomass from 17.5 ± 0.15% to 33.5 ± 0.3 % recorded in summer. In winter, biomass carbohydrate increased from 18.3 ± 1.2% to 35.8 ± 0.3%.To induce accumulation of carbohydrates through nitrogen starvation, isolated microalgal species native to the HRAOPs of the IAPS at Institute for Environmental Biotechnology Rhodes University(EBRU) were used. The outcome from the laboratory studies showed that carbon partitioning within isolated strains could be altered from carbohydrate to lipid which is more energy-rich. Hence, exploring the biodiesel production option using HRAOP MaB-floc biomass, which had a lipid content ranging between 12.1 ± 0.64 % and 13.9 ± 0.5 %, would require a preconditioning step in the form of nitrogen starvation to enhance its lipid content. Overall, the outcome of outdoor monitoring studies on biomass biochemical composition indicated that HRAOPs operating under natural environmental conditions preferentially generated a biomass rich in carbohydrate. Therefore, anaerobic digestion may be a more viable option for HRAOP MaB-floc biomass because of the high carbohydrate levels ranging between 24.9 ± 0.6 % and 25.6 ± 1.3 % of the dry MaB-floc biomass weight. Despite the low biomass C/N ratio (7.1 to 7.8), the MaB-floc biomass can be anaerobically co-digested with a higher C/N ratio (24) substrate such as in-pond digester sludge, to improve methane yields calculated to be between 0.31 m3 CH4/ kg MaB-floc biomass and 0.33 m3 CH4/ kg MaB-floc biomass. Anaerobic digestion of biomass also produces CO2 which can be recovered and added to HRAOPs to enhance MaB-floc biomass productivity while lowering greenhouse gas emissions from a wastewater treatment plant. The digestate from the anaerobic process, which is rich in nitrogen and phosphorus can be used as a biofertiliser. Thus, a potential MaB-floc biomass biorefinery consisting of biogas and bio-fertiliser pathways can be established using IAPS treating sewage as the platform technology. IAPS is a system designed to operate in a way that is passive and without substantial environmental impact but technological innovations and a reduction in the size of the system are required to make the technology more acceptable.
  • Full Text:
  • Date Issued: 2020

Performance of an integrated algal pond for treatment of domestic sewage: a process audit

  • Authors: Dube, Anele
  • Date: 2020
  • Subjects: Water -- Purification , Sewage -- Purification -- Anaerobic treatment , Algae -- Biotechnology , Waste disposal -- South Africa , Integrated algae pond systems (IAPS)
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/167043 , vital:41432
  • Description: Integrated algae pond systems (IAPS) are energy efficient, robust, passive systems that use the principles of fermentation, photosynthesis and microbial metabolism to remediate wastewater, producing a good quality effluent with reuse potential. In addition to the treatment of wastewater, IAPS have the ability to generate two additional product streams viz. biogas and biomass. The latter adds to the attractiveness of the system. However, the implementation of this technology, like many passive systems, has remained limited at a commercial scale, and the inclination is still towards grey technologies. The aim of this research was to investigate the capabilities and potential of a demonstration-scale IAPS and use results obtained to establish a process audit framework. The aspects considered for the audit included performance efficiency, effluent water quality, biomass composition, quantity and productivity within the ponds, and cost analysis of operation and maintenance over a 9-year period. Plant performance was closely monitored during the course of the study and this led to a review of previously adopted plant management strategies. Troubleshooting exercises were also carried out when plant performance declined. Results showed that IAPS efficiently reduced standard water parameters with the exception of pH, dissolved oxygen, and nitrate whose values increased from raw influent to final effluent. The following water quality parameters were established for the final effluent: total suspended solids 55 ± 7.1 mg. L-1 (n = 28); chemical oxygen demand 94.1 ± 10.6 mg. L-1 (n = 28) (after removal of algae); pH 9.9 ± 0.01 (n = 26); ammonium nitrogen 1.7 ± 0.3 mg. L-1 (n = 25); nitrate 3.3 ± 0.6 mg. L-1 (n = 25); ortho-phosphate 1.6 ± 0.2 mg. L-1 (n = 25); electrical conductivity 98.7 ± 2.0 mS m-1 (n = 26) and faecal coliforms (per 100 mL) 1482.6 ± 636.0 (n = 24). The final effluent measured consistently high chemical oxygen demand and total suspended solids, however close analysis showed that total suspended solids could be controlled by increasing the frequency of removal of settled biomass within the settling ponds. Biomass produced contained microalgae, bacteria, metazoa, and protozoa. The biomass productivity achieved was as high as 130.6 kg ha-1 d-1; however, about 33% was lost to the final effluent due to inadequate settling. Results obtained during the course of this study and outcomes of earlier work on IAPS are taken as the baseline to determine parameters needed for the development of the process audit framework. Techniques utilised to derive the blue print process audit protocol for IAPS included a turtle diagram, a flow diagram and a checklist. Attention to plant management proved vital in determining overall performance. Cost, including operating and maintenance, of treating water using the demonstration scale system on a per person equivalent per year basis was determined as ZAR 123.87 (where, ZAR to USD = 0.07).
  • Full Text:
  • Date Issued: 2020

Towards the development of a bio-fertiliser using mixed liquor from high rate algal oxidation ponds

  • Authors: Masudi, Wiya Léon
  • Date: 2020
  • Subjects: Biofertilizers , Microalgae - Biotechnology , Algae -- Culture
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/142969 , vital:38181
  • Description: Mixed liquor includes consortia of microalgae and bacteria produced in high rate algal oxidation ponds (HRAOPs). The consortia of microalgae and bacteria occur as flocs called microalgae-bacterial flocs (MaB-flocs). This study aimed to source bacteria from MaB-flocs generated in HRAOPs and, after isolation and identification, evaluate their potential as plant growth promoting (PGP) microorganisms. Twelve bacterial strains namely ECCN 1b, ECCN 2b, ECCN 3b, ECCN 4b, ECCN 5b, ECCN 6b, ECCN 7b, ECCN 8b, ECCN 9b, ECCN 10b, ECCN 11b, and ECCN 12b were successfully isolated and their molecular identity established using amplified 16S rRNA gene sequence analysis that was compared to sequences deposited in the NCBI gene database. Blast analysis identified these isolates at the genus level as Bacillus strain ECCN 1b, Fictibacillus strain ECCN 2b, Bacillus strain ECCN 3b, Aeromonas strain ECCN 4b, Exiguobacterium strain ECCN 5b, Arthrobacter strain ECCN 6b, Enterobacter strain ECCN 7b, Exiguobacterium strain ECCN 8b, Microbacterium strain ECCN 9b, Pseudomonas ECCN strain 10b, Ancylobacter strain ECCN 11b and Microbacterium strain ECCN 12b. These isolates were able to grow in nutrient broth in a pH range between 6 and 10, with the best growth achieved at pH 8 to 9. The results on the use of carbon substrate revealed that 5 strains including Arthrobacter strain ECCN 6b, Aeromonas strain ECCN 4b, Pseudomonas strain ECCN 10b, Enterobacter strain ECCN 7b and Bacillus strain ECCN 3b were capable of using glucose, sucrose and mannitol. No faecal coliforms were found. However, of the 12 isolates screened for bio-fertilisation potential, Bacillus strain ECCN 1b, Fictibacillus strain ECCN 2b, Bacillus strain ECCN 3b, Aeromonas strain ECCN 4b, Exiguobacterium strain ECCN 5b, Arthrobacter strain ECCN 6b, Enterobacter ECCN strain 7b, Exiguobacterium strain ECCN 8b and Pseudomonas strain ECCN 10b showed multifunctional plant growth promoting (PGP) potential. The potential for PGP included the production of ammonium-N, solubilisation of phosphate-P and potassium-K, oxidation of Mn and production of auxin, indole-3-acetic acid (IAA). Results are discussed in terms of the amount or concentration (mg L-1) of plant essential nutrient and growth regulator produced by these isolated bacteria. Even so, further studies are needed to test and confirm the bio-fertiliser and plant growth promoting activity of these strains in pot trials and field experiments, or both.
  • Full Text:
  • Date Issued: 2020

Bacterial colonisation and degradation of geologically weathered and discard coal

  • Authors: Olawale, Jacob Taiwo
  • Date: 2018
  • Subjects: Coal mine waste , Coal -- Biodegradation , Coal mines and mining -- Environmental aspects , Land degradation , Electron microscopy , Extracellular polymeric substances , Flagella (Microbiology) , Fourier transform infrared spectroscopy , Microbiologically influenced corrosion
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/61625 , vital:28043
  • Description: Bacterial beneficiation of low-grade coal, coal discard, and waste has the potential to mitigate land degradation, water and soil pollution and, be a strategy for mining companies to responsibly extract and process coal with environmental sustainability. This study investigated the colonisation and biodegradation or depolymerisation of coal discard and geologically weathered coal by selected strains of bacteria, and an attempt has been made to describe the mechanisms associated with colonisation and biodegradation of this carbonaceous material. Ten bacterial strains, Bacillus strain ECCN 18b, Citrobacter strain ECCN 19b, Proteus strain ECCN 20b, Exiguobacterium strain ECCN 21b, Microbacterium strain ECCN 22b, Proteus strain ECCN 23b, Serratia strain ECCN 24b, Escherichia strain ECCN 25b, Bacillus strain ECCN 26b and Bacillus strain ECCN 41b, isolated from diesel-contaminated soil and coal slurry and identified using DNA sequencing, were rescreened and their coal biodegradation potential ranked. The ranking of the bacterial strains was undertaken using several indicators including; formation of brown halos on the plate culture (solid), change in colour intensity of the medium in liquid culture, change in culture media pH, and an increase in absorbance at 280nm and 450nm. Although, all the ten strains showed evidence of biodegradation of coal discard and geologically weathered coal based on the ranking employed, and the three strains considered the best candidates were Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. The actions of the three bacterial strains were further studied and characterised in relation to coal degradation. Electron microscopy revealed that Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b attached to the surface of coal discard and geologically weathered coal by a process that appeared to involve extracellular polymeric substances (EPS), and flagella. The presence of flagella for Citrobacter strain ECCN 19b and Serratia strain ECCN 24b was confirmed by transmission electron microscopy. Bacterial degradation of coal discard and geologically weathered coal by these selected strains resulted in the release of soluble and insoluble products. Ultraviolet/ visible spectrophotometric (UV/VIS) analysis revealed that the soluble products resembled humic acid-like substances, which was confirmed following Fourier Transform Infrared (FTIR) spectroscopy. Analysis revealed that the coal-derived humic acid-like substances were similar to commercial humic acid extracted from bituminous coal. Elemental analysis of the insoluble product residue after bacterial biodegradation revealed the modification of the chemical compositions of the coal discard and geologically weathered coal substrates. Characterisation of the functional groups of the insoluble product using FTIR spectroscopy indicated changes, with the appearance of new peaks at 1737cm-1, 1366cm-1, 1228cm-1, and 1216cm-1 characteristic of aldehyde, ketones, carboxylic acids, esters, amines, and alkanes. Broad spectra regions of 3500 -3200cm-1, characteristic of alcohol and phenol, were also observed. Together, these results were taken as evidence for increased oxidation of the coal substrates, presumably as a consequence of bacterial catalysed biodegradation of coal discard and geologically weathered coal. During bacterial degradation of coal discard and geologically weathered coal, strains produced extracellular protein, which was detected and further investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE). At least three protein bands with molecular mass 53 kDa, 72 kDa, and 82 kDa were common to the three bacterial strains. Following ammonium sulphate precipitation and gel filtration chromatography, additional bands with molecular mass 16 kDa, 33 kDa, 37 kDa, and 43 kDa were detected. An extracellular laccase activity was detected in cultures of Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. Cytochrome P450 activity was detected in all the bacterial strains in the presence of both coal discard and geologically weathered coal. This is the first time that cytochrome P450 activity has been reported following exposure of these three bacterial strains to a coal substrate. Overall, this research has successfully demonstrated the partial degradation of coal discard and geologically weathered coal by Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b and the release of humic acid-like substances. Thus, the biodegradation process involved adherence to and growth of the bacteria on the surface of coal substrate and appeared to require the formation of alkaline substances and the combined activities of extracellular LAC and cytochrome P450. Since bacterial degradation of low-grade coal and discard appears to be viable, the bacteria isolated in this study can potentially be used either for conversion of discard into valuable chemicals or to mitigate the deleterious effects of stockpiled coal discard on the environment.
  • Full Text:
  • Date Issued: 2018

Performance evaluation and cost analysis of subsurface flow constructed wetlands designed for ammonium-nitrogen removal

  • Authors: Tebitendwa, Sylvie Muwanga
  • Date: 2018
  • Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/61808 , vital:28062
  • Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
  • Full Text:
  • Date Issued: 2018

Water quality, biomass and extracellular polymeric substances in an integrated algae pond system

  • Authors: Jimoh, Taobat Adekilekun
  • Date: 2018
  • Subjects: Water -- Purification , Sewage -- Purification -- Anaerobic treatment , Sewage lagoons , Sewage disposal plants , ASPAM model (Acid mine drainage) , Integrated algae pond systems (IAPS)
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/57307 , vital:26871
  • Description: Integrated algae pond systems (IAPS) combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Although, IAPS as a technology process offers many advantages including efficient and simultaneous N and P removal, no requirement for additional chemicals, O2 generation, CO2 mitigation, and a biomass with potential for valorization, a lack of technological advancement and the need for large land area, has limited the reach of this technology at industrial scale. In mitigation, peroxonation was introduced as a tertiary treatment unit and its effect on COD and TSS of IAPS treated water investigated. An effort was made to characterize the soluble but persistent COD in IAPS treated water and, productivity of the HRAOP mixed liquor was investigated to gain insight into the potential use of this biomass. Results show that peroxone treatment effectively reduced COD, TSS, and nutrient load of IAPS water without any significant impact on land area requirement. Indeed, summary data describing the effect of peroxone on quality of IAPS-treated water confirmed that it complies with the general limit values for either irrigation or discharge into a water resource that is not a listed water resource for volumes up to 2 ML of treated wastewater on any given day. Extraction followed by FT-IR spectroscopy was used to confirm albeit tentatively, the identity of the soluble but persistent COD in IAPS treated water as MaB-floc EPS. Results show that MaB-flocs from HRAOPs are assemblages of microorganisms produced as discrete aggregates as a result of microbial EPS production. A relationship between photosynthesis and EPS production was established by quantification of the EPS following exposure of MaB-flocs to either continuous light or darkness. Several novel strains of bacteria were isolated from HRAOP mixed liquor and 16S ribosomal genomic sequence analysis resulted in the molecular characterization of Planococcus maitriensis strain ECCN 45b. This is the first report of Planococcus maitriensis from a wastewater treatment process. Productivity and change in MaB-flocs concentration, measured as mixed liquor suspended solids (MLSS) between morning and evening were monitored and revealed that MLSS is composed of microalgae and bacteria but not fungi. Concentration varied from 77 mg L-1 in September (winter) to 285 mg L-1 in November (spring); pond productivity increased from 5.8 g m-2 d-1 (winter) to 21.5 g m-2 d-1 (spring); and, irrespective of MLSS concentration in late afternoon, approximately 39% was lost overnight, which presumably occurred due to passive removal by the algae settling pond. The outcomes of this research are discussed in terms of the quality of treated water, and the further development of IAPS as a platform technology for establishing a biorefinery within the wastewater treatment sector.
  • Full Text:
  • Date Issued: 2018

Evaluation of Fungcoal as a bioprocess technology for self-cladding of waste coal dumps

  • Authors: Sekhohola, Lerato M
  • Date: 2016
  • Subjects: Coal mine waste , Fungi -- Biotechnology , Coal -- Biodegradation , Bermuda grass -- Biotechnology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5959 , http://hdl.handle.net/10962/d1019992
  • Description: Low-grade coal, a poor source of energy, has long been regarded as waste material by the coal mining industry. Biological degradation of this coal material by ligninolytic fungal strains presents a viable strategy towards eliminating this unusable fossil fuel. To this end, a novel and patented bioprocess termed Fungcoal was developed. Fungcoal is a biological process utilised in the in situ treatment of waste coal and is based on the mutualistic relationship between the fungus Neosartorya fischeri and the graminaceous species Cynodon dactylon. The process facilitates the rapid conversion of waste coal into soil-like material that stimulates establishment of vegetation for eventual coal dump rehabilitation. While a number of in vitro studies have identified various fungal strains as efficient coal degraders, the mechanisms involved in the Fungcoal-stimulated degradation process have not been fully elucidated. Furthermore, implementation of Fungcoal at both pilot and commercial scale has not been achieved. Thus the objective of this work was to investigate Fungcoal as a bioprocess via examining the role of coal degrading fungi (CDF) and grasses as biocatalysts in coal biodegradation and for the self-cladding of waste coal dumps. Initially, waste coal degradation by N. fischeri, strain ECCN 84, was investigated, specifically focusing on the mechanisms underpinning the process. In vitro studies showed the addition of waste coal induced active fungal colonisation resulting in increased fungal biomass. Increased extracellular laccase (LAC) activity, occuring concomitantly with an increase in hyphal peroxisome proliferation, was also observed in the coal supplied fungal cultures. Analysis of the colonised waste coal revealed a time dependent reduction in the percentage weight of elemental carbon coupled with an increase in elemental oxygen. The results supported metabolism and degradation of waste coal by N. fischeri strain ECCN 84 and involvement of fungal extracellular laccase. The contribution of C. dactylon, a C4 grass species to in situ biodegradation of waste coal in the presence of coal degrading and mycorrhizal fungi (MF) was also investigated. Enhanced degradation of the waste coal into a humic soil-like material was observed within the rhizosphere. Analysis of the resultant substrate revealed an increased concentration of highly oxidised humic-like substances (HS). Fungi remained viable in the rhizosphere up to 47 weeks post-inoculation and cultivation of C. dactylon, indicating the resultant humic substance-rich rhizosphere provided an environment conducive for microbial proliferation and activity. Furthermore, humic substance enrichment of waste coal substrates supported germination and seedling emergence of several agronomic species including Zea mays (corn), Phaseolus vulgaris (bean), Pisum sativum (pea), and Spinacia oleracea (spinach). Use of various cladding materials to support coal biodegradation, by fungus-grass mutualism and rehabilitation of waste dumps was evaluated at commercial scale. While substantial physico-chemical changes were not evident in the absence of cladding or where waste coal was used as cladding material, successful establishment of grass cover and diversity was achieved within three hydrological cycles on dumps cladded with weathered coal. Work presented in this thesis successfully demonstrates the degradation of waste coal by N. fischeri. The biodegradation process included enhanced extracellular LAC activity coupled with increased 3 waste coal oxidation. Increased HS concentration of waste coal substrate supported germination and early seedling establishment of several agronomic species. At commercial scale a co-substrate in the form of carbon-rich weathered coal was essential to support fungus-grass mutualism and Fungcoal-induced rehabilitation. These findings support the developed Fungcoal concept and the underpinning rationale that the phyto-biodegradation of waste coal indeed depends on the mutualistic interactions between grass root exudates and the ligninolytic and mycorrhizal fungi. Taken together, these findings provide practical evidence of the contribution of fungi and grasses as mutualists in the biodegradation of waste coal and sustainable rehabilitation of waste coal dumps
  • Full Text:
  • Date Issued: 2016

Integrated Algae Pond Systems for the Treatment of Municipal Wastewater

  • Authors: Mambo, Mutsa Prudence
  • Date: 2016
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5960 , http://hdl.handle.net/10962/d1021258
  • Description: Integrated algae pond systems are a derivation of the Oswald designed advanced integrated wastewater ponding system, and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Integrated algae pond system technology was introduced to South Africa in 1996 and a pilot plant was designed and commissioned at the Belmont Valley wastewater treatment works in Grahamstown. Previous studies showed that this system delivered a final effluent superior to most pond systems deployed in South Africa but that it was unable to meet the general standard for nutrient removal and effluent discharge. This study was initiated to re-appraise integrated algae pond systems and to assess the potential of the technology as an effective municipal sewage treatment system. And more...
  • Full Text:
  • Date Issued: 2016

Post-treatment technologies for integrated algal pond systems

  • Authors: Westensee, Dirk Karl
  • Date: 2015
  • Subjects: Sewage disposal plants -- South Africa -- Grahamstown , Water -- Purification -- Filtration , Water -- Purification -- Slow sand filtration , Sewage -- Purification -- Anaerobic treatment , Sewage -- Purification -- Biological treatment , Algae -- Biotechnology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5958 , http://hdl.handle.net/10962/d1018180
  • Description: Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation and affords a secondarily treated water for reclamation according to its design specifications which most closely resemble those of the AIWPS® Advanced Secondary Process developed by Oswald. As a consequence, and as might be expected, while the technology performed well and delivered a final effluent superior to most pond systems deployed in South Africa it was unable to meet The Department of Water Affairs General Standard for nutrient removal and effluent discharge. The work described in this thesis involved the design, construction, and evaluation of several tertiary treatment units (TTU') for incorporation into the IAPS process design. Included were; Maturation Ponds (MP), Slow Sand Filter (SSF) and Rock Filters (RF). Three MP's were constructed in series with a 12 day retention time and operated in parallel with a two-layered SSF and a three-stage RF. Water quality of the effluent emerging from each of these TTU's was monitored over a 10 month period. Significant decreases in the chemical oxygen demand (COD), ammonium-N, phosphate-P, nitrate-N, faecal coliforms (FC) and total coliforms (TC) were achieved by these TTU's. On average, throughout the testing period, water quality was within the statutory limit for discharge to a water course that is not a listed water course, with the exception of the total suspended solids (TSS). The RF was determined as the most suitable TTU for commercial use due to production of a better quality water, smaller footprint, lower construction costs and less maintenance required. From the results of this investigation it is concluded that commercial deployment of IAPS for the treatment of municipal sewage requires the inclusion of a suitable TTU. Furthermore, and based on the findings presented, RF appears most appropriate to ensure that quality of the final effluent meets the standard for discharge.
  • Full Text:
  • Date Issued: 2015

Exploring the fertiliser potential of biosolids from algae integrated wastewater treatment systems

  • Authors: Mlambo, Patricia Zanele
  • Date: 2014
  • Subjects: Sewage disposal plants , Sewage sludge as fertilizer , Algae -- Biotechnology , Sewage -- Purification -- Anaerobic treatment , Plant regulators , Biofertilizers , Microalgae -- Biotechnology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5957 , http://hdl.handle.net/10962/d1013342
  • Description: High rate algae oxidation ponds (HRAOP) for domestic wastewater treatment generate biosolids that are predominantly microalgae. Consequently, HRAOP biosolids are enriched with minerals, amino acids, nutrients and possibly contain plant growth regulator (PGR)-like substances, which makes HRAOP biosolids attractive as fertiliser or PGR. This study investigated HRAOP biosolids as a starting material for a natural, cost-effective and readily-available eco-friendly organic fertiliser and/or PGRs. Various HRAOP extract formulations were prepared and their effect on plant growth and development was evaluated using selected bioassays. Initial screening included assessing the effect on change in specific leaf area, radish cotyledon expansion as an indicator of PGR-like activity, and seed germination index (GI). More detailed studies on fertiliser efficacy and PGR-like activity utilised bean (Phaseolus vulgaris) and tomato (Solanum lycopersicum) plants. Combined effects of sonicated (S) and 40% v/v methanol (M) extract (5:1 SM) had impressive plant responses, comparable to Hoagland solution (HS). Other potentially fertiliser formulations included 0.5% M, 1% M, 2.5% S and 5% S formulations. The 5:1 SM and 5% S showed greater PGR-like activity, promoting cotyledon expansion by 459 ± 0.02% and 362 ± 0.01%, respectively. GI data showed that none of the formulations negatively impacted germination. Further investigation showed that the 5% S formulation increased leaf length, width and area by 6.69 ± 0.24, 6.21 ± 0.2 mm and 41.55 ± 0.2 mm². All formulated fertiliser extracts had no adverse effect on chlorophyll content and plant nutrient balance as indicated by C:N (8-10:1) ratio. In addition, plants appeared to actively mobilise nutrients to regions where needed as evidenced by a shift in shoot: root ratio depending on C, N and water availability. Furthermore, 5% S caused a 75% increase in tomato productivity and had no effect on bean productivity. Whereas, 5:1 SM and 1% M formulation improved bean pod production by 33.3% and 11%, respectively but did not affect tomato production. Harvest index (HI) however indicated a 3% reduction in tomato productivity with 5:1 SM and little or no enhancement in bean productivity with both 5:1 SM and 5% S treatments. Bean plants treated with 5:1 SM and 5% S produced larger fruits, which could be an indication of the presence of a PGR effect. Overall, HRAOP biosolids extracts prepared and investigated in this study demonstrated both fertiliser characteristics and PGR-like activity with performances comparable and in some cases exceeding that of commercial products. However additional research is needed to confirm presence of PGR-like activities and fertiliser efficacy.
  • Full Text:
  • Date Issued: 2014

Microalgae biomass as fermentation feedstock

  • Authors: Tijjani-Oshungboye, Kubura
  • Date: 2012
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5956 , http://hdl.handle.net/10962/d1006168
  • Description: The search for alternative energy is as a result of pollution generated by the utilization of fossil fuel. Bearing in mind the increase in demand which exceeds supply, alternative energy must reduce the carbon foot print in order to relieve use of fossil fuels. Biogas generation from wastes is an old technology that has been in existence for decades. This same concept was behind the development of the integrated algae ponding system (IAPS), where the use of microalgae biomass is adopted for waste water treatment and, anaerobic digestion which is a component of the IAPS, simultaneously generates biogas. The biogas from the IAPS was quantified in order to evaluate efficiency of the system and the anaerobic fermentation pit was also simulated in the laboratory to optimize biogas production using microalgae as co-fermentation feedstock. Microalgae biomass was evaluated as potential feedstock for ethanol fermentation and the use of biogas was investigated as an alternative transportation fuel. In an IAPS substantial biomass is produced on an annual basis. For effective treatment of waste water and efficient nutrient removal continuous harvest of the biomass is required. In the present study, water treatment efficiency of the EBRU IAPS was determined by carrying out a series of tests to investigate the decline in nutrient content from port of influent entry to effluent discharge. There was more than a 60% reduction in nutrient content with a concomitant increase in biomass and growth rate of 0.25 g/L . Biogas generated from the IAPS was quantified using a flow meter and the composition determined by gas chromatography. Methane which is the principal constituent of biogas was 75% (±SD, n=IO) and 2.34 m³.d⁻¹ was measured as biogas yield from the EBRU IAPS. The study also investigated the use of the excess microalgae biomass as a fermentation feedstock for ethanol production and as a co-substrate in order to increase biogas yield from the system. Positive results were achieved for ethanol production from microalgae although yield was generally low. About 385 mg.⁻¹ of ethanol was recovered when glucose was used as substrate, where as only 115 mg.⁻¹ of ethanol was recovered with microalgae as substrate. Suitability of microalgae as feedstock for ethanol generation and biogas generation was determined by characterisation which involved estimation of the carbohydrate, protein and lipid content, and analysis of the C, H, 0, Nand S content. Laboratory fed batch reactors simulated the anaerobic digestion process in order to study the effect of microalgae biomass as co-substrate for biogas generation. The fermenters were inoculated with an active consortium obtained from the Makana municipal waste water works and microbial studies were carried to confirm the presence of the anaerobic consortium. Different pre-treatments (concentrated, rupturing and freeze-drying) were used to disrupt the microalgae prior to introduction into fermenters in a ratio of 3: I. COD, TC, TOC, SO₄⁻² and TN analyses were carried out to monitor nutrient depletion in the system, and biogas generated by the system was quantified by volumetric analysis and the gas composition determined. Statistical analysis (ANOVA) was used to test for significant difference pre and post addition of microalgae. In the most effective fermenter, biogas production was at an average of 394 ml.d·' and CH₄ ratio in the biogas increased by over a 100%. Theoretical methane potential of the IAPS and the Makana municipal waste water works treating 5 ML.d⁻¹ of domestic waste was determined using the empirical formula of waste water and shown to yield 1,037,342.40 m³/yr. The projected biogas yield from this system was used to evaluate its potential use as transportation fuel. In total, 198,673 .55 m³ of biogas was estimated to be required to fuel the Rhodes University's fleet of vehicles, with a residual biogas stream of 838,668.85 m³. It was also demonstrated in the present study that renewable energy sourced from biomass has the potential of supplanting the use of fossil fuel resulting in less pollution leading to a cleaner and healthier environment.
  • Full Text:
  • Date Issued: 2012

Towards a sustainable bioprocess for the remediation of acid mine drainage

  • Authors: Mambo, Mutsa Prudence
  • Date: 2011
  • Subjects: Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5955 , http://hdl.handle.net/10962/d1006167 , Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
  • Description: Acid mine drainage is of growing concern for both developing and developed economies. Thus there is increasing pressure to develop alternative remediation strategies. Biological sulphidogenic mechanisms have long since been studied but, very few have been implemented on a large scale. Limitations are due to the inability to acquire a suitable, low cost, environmentally friendly, renewable carbon source. The present study investigated the use of an algae biomass generated by the HRAOP of an IAPS as a carbon source for the EBRU 00AB/06 SRB consortium. The algae biomass and consortium were utilized together to remediate simulated AMD. Remediation involved decreasing the sulphate and metal concentrations in solution and decreasing the acidity of a simulated AMD. Experiments were carried out to investigate the capability of the EBRU 00AB/06 SRB consortium for sulphate reduction and sulphide generation. The consortium produced colonies when grown under anaerobic conditions in Petri dishes containing modified lactate SRB medium. The SRB consortium reduced the sulphate concentration of modified Postgates medium B and generated sulphide. Further analysis of the EBRU 00AB/06 SRB consortium revealed that the consortium was minimally impacted at pH 5 and by sulphate and iron at 3 g.L-1 and 0.5 g.L-1 respectively. The EBRU 00AB/06 SRB consortium was exposed to Actinomycin D and Ethidium Bromide to determine whether transcription and translation of proteins was required for sulphate reduction. Results indicated that sulphide generation and sulphate reduction were inducible. Analysis of the algae biomass used in this study revealed the empirical formula C1.0H1.91N0.084S0.003O0.36 indicating a carbon source rich in the nutrients required to sustain microbial development. Light microscopy revealed that algae cell walls and in particular those of Pediastrum were susceptible to acid hydrolysis. Dinitrosalicylic acid, Nile red, Bradford and Ninhydrin assays were used to determine the reducing sugar, lipid, protein and amino acid content respectively, of the mixed algae biomass. Results showed that upon exposure of the biomass to simulated AMD at pH 1 and pH 3, the concentration of reducing sugars and amino acids in solution increased. Whereas levels of lipids remained unchanged while the protein concentration decreased, indicating that, upon exposure of algae biomass to AMD, simulated or otherwise, cells ruptured, proteins were hydrolyzed and polysaccharides were broken down to sugars which are immediately available for SRB utilization. Exposure of biomass to simulated AMD revealed further that the presence of algae biomass increased the pH of simulated AMD (pH 3) to pH 7.67 after 4 d. Likewise, the pH of simulated AMD at 1 increased to 1.77 after 2 d while pH of the neutral control increased to 8.1 after 4 d. A direct comparison between lactate and algae biomass revealed 94 % sulphate removal after 23 d in the presence of algae biomass while 82 % sulphate removal was measured in the presence of lactate. Thus the EBRU 00AB/06 SRB consortium successfully utilized algae biomass for sulphate reduction and sulphide generation. In another experiment to establish if the consortium could remediate simulated AMD (pH 5) containing 0.5 g.L-1 iron and 3 g.L-1 sulphate while utilizing an algae biomass as the carbon source no residual iron was detected after 14 d and by day 23, an 89.07 % reduction in sulphate was measured. The results of this investigation are discussed in terms of utilizing a readily available and renewable biomass in the form of microalgae produced in HRAOPs as an effective carbon source in the SRB catalysed remediation of AMD.
  • Full Text:
  • Date Issued: 2011
  • 1
  • Disclaimer
  • Privacy
  • Copyright
  • Contact