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Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215

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Author: search.filters.author.Chollom, Martha Noro

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    Prospects of synthesized magnetic TiO2-based membranes for wastewater treatment : a review
    (MDPI AG, 2021-06) Tetteh, E. Kweinor; Rathilal, S.; Asante-Sackey, D.; Chollom, Martha Noro
    Global accessibility to clean water has stressed the need to develop advanced technologies for the removal of toxic organic and inorganic pollutants and pathogens from wastewater to meet stringent discharge water quality limits. Conventionally, the high separation efficiencies, relative low costs, small footprint, and ease of operation associated with integrated photocatalytic-membrane (IPM) technologies are gaining an all-inclusive attention. Conversely, photocatalysis and membrane technologies face some degree of setbacks, which limit their worldwide application in wastewater settings for the treatment of emerging contaminants. Therefore, this review elucidated titanium dioxide (TiO2), based on its unique properties (low cost, non-toxicity, biocompatibility, and high chemical stability), to have great potential in engineering photocatalytic-based membranes for reclamation of wastewater for re-use. The environmental pathway of TiO2 nanoparticles, membranes and configuration types, modification process, characteristics, and applications of IPMs in water settings are discussed. Future research and prospects of magnetized TiO2-based membrane technology is highlighted as a viable water purification technology to mitigate fouling in the membrane process and photocatalyst recoverability. In addition, exploring life cycle assessment research would also aid in utilizing the concept and pressing for large-scale application of this technology.
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    Fouling control in a woven fibre microfiltration membrane for water treatment
    (Korean Society of Environmental Engineering, 2019-10-11) Chollom, Martha Noro; Rathilal, Sudesh; Pikwa, Kumnandi; May, Lingham
    Korean Society of Environmental Engineers. Current available commercial membranes are not robust and are therefore destroyed if left to dry out or handled roughly. Woven fibre microfiltration (WFMF) membranes have advantages over its competitors with respect to durability, thus, favourable for the developing economies and operation during rough conditions. Evaluation of the effects of aeration and brushing as a flux enhancement strategies for WFMF membrane was the purpose of this study. The WFMF membrane was found to be susceptible to pore plugging by colloidal material and adsorption/attachment by microbiological contaminants. This led to a 50% loss in flux. Aeration as a single flux enhancement strategy proved insufficient to maintain high flux successfully. Therefore combined flux enhancement strategies yielded the best results.
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    Anaerobic treatment of slaugterhouse wastewater: evaluating operating conditions
    (WIT Press, 2019-12-11) Chollom, Martha Noro; Rathilal, Sudesh; Swalaha, Feroz Mahomed; Bakare, Babatunde F.; Tetteh, Emmanuel K.
    The aim of the study was to elucidate the effect of process parameters on the performance of an upflow anaerobic sludge blanket reactor (UASB) that was treating slaughterhouse wastewater. The UASB reactor was operated continuously under mesophilic conditions to evaluate its performance with respect to the removal of organics and, at the same time, monitor biogas production. Organic loading rate (OLR) was varied while keeping the hydraulic retention time (HRT) constant. Chemical oxygen demand (COD) removal efficiency higher than 75% was achieved at an OLR of 9 kg.COD.m-3.d-1, with a HRT of 12 h. Bulking sludge problems were not observed during the reactor operation period. Stability of the treatment process was achieved by the natural buffering of the system due to the produced alkalinity and also due to the characteristics of the wastewaters which was found to be rich in proteins and fatty acids.
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    Fouling and cleaning in osmotically driven membranes
    (InTechOpen, 2018-03-06) Chollom, Martha Noro; Rathilal, Sudesh
    Fouling is a phenomenon that occurs in all membrane processes. It is a complex problem, which limits the full operation of this technology. Fouling in pressure-driven membranes (PDMs) has been studied extensively, and the occurrence is well understood in that methods of mitigation have been proposed; however, limitations still occur for their full implementation. The use of osmotically driven membranes (ODMs) for water treatment is an emerging technology, which has shown some advantages such as low hydraulic pressure operation, high solute rejection and high recovery over PDMs. However, like in PDMs, fouling still presents a challenge. This chapter is aimed at evaluating the impact of fouling on the ODM performance, exploring the factors and mechanisms governing the fouling behaviour, developing approaches for mitigating fouling, elucidating the effect of membrane fouling and providing mitigation strategies as well as the causes of fouling in ODMs.
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    Fouling mitigation on a woven fibre microfiltration membrane for the treatment of raw water
    (Institution of Chemical Engineers, 2017-06) Chollom, Martha Noro; Pikwa, Kumnandi; Rathilal, Sudesh; Pillay, Visvanathan Lingamurti
    The main source of drinking water in rural areas of South Africa is surface water. Improving drinking water and sanitation facilities alone does not completely solve the problem of waterborne diseases. A novel simple gravity driven filtration unit incorporated with the woven fibre microfiltration (WFMF) membranes was developed for the treatment of raw water for drinking purposes. However, these membranes are susceptible to fouling which reduces flux permeation. This paper focused on evaluating the fouling mitigation strategies to improve on performance of the woven fibre membrane filtration unit with respect to fouling and flux recovery. The study found that the WFMF membrane fouled both internally by pore plugging and externally by adsorption and deposition on the membrane. As a result, a single flux enhancement strategy proved insufficient to maintain high flux successfully. A combination of strategies gave the best optimum conditions for flux production. Backwashing with a combination of brushing yielded the highest recovery of 187%. Soaking the membranes in 0.2% hypochlorite for an hour and thereafter by brushing them yielded 93% flux recovery. Mechanical cleaning however yielded the best result with 97% flux recovery. It was concluded that the selected strategies were the most successful strategies to prevent a sharp decline in flux due to fouling and giving high average flux for the filtration period.
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    Development and evaluation of a small scale water disinfection system
    (IWA Publishing, 2016-07-08) Alfa, Dorcas; Rathilal, Sudesh; Pikwa, Kumnandi; Chollom, Martha Noro; Pillay, Visvanathan Lingamurti
    Provision of microbiologically safe drinking water for people living in the rural areas of developing countries remains a major challenge to date. A simple gravity-driven membrane point of use system was developed based on woven fabric microfiltration (WFMF) membranes. The WFMF is a loose type of membrane (0.45 μm). However, complete disinfection is not achieved with the WFMF, hence it was incorporated with two disinfectants. This study aimed to combine the WFMF with two disinfectants (Water guard and bromochlor tablets) to bring the water to the accepted quality for drinking. Four different types of water were sourced, considering two factors; E. coli and turbidity content. The WFMF demonstrated excellent filtration performance by producing permeates with turbidity less than 1 NTU for feed turbidity ranging between 10 and 200 NTU. There was 95–99.8% E. coli removal for raw feeds with influent E. coli ranging between 500 and 44,500 CFU/100 mL. Total disinfection was achieved with both disinfectants, however, the effectiveness of the chemical disinfectants in E. coli removal was affected by the quality of water to be disinfected. The study showed that turbidity plays a major role in disinfection performances by increasing chlorine demand on water sources with high turbidity levels.
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    The applicability of nanofiltration for the treatment and reuse of textile reactive dye effluent
    (AJOL, 2015) Chollom, Martha Noro; Rathilal, Sudesh; Pillay, Visvanathan Lingamurti; Alfa, Dorcas
    The main aim of the study was to test the feasibility of using nanofiltration (NF) processes for the treatment of reactive dye-bath effluents from the textile industry, in order to recover the water and chemicals (salts) for reuse purposes. The study of the reusability of nanofiltered water for dyeing has been given little or no attention. About 30% of reactive dyes remain unfixed on fibres; the unfixed dyes are responsible for the colouration in effluents. Membrane processes were employed to treat reactive dye-bath effluents to recover the salts and water. Investigations were conducted firstly with ultrafiltration (UF) used as a pre-treatment for NF. Secondly, evaluations were performed for 2 types of NF membranes (SR90 and NF90), in terms of quality of permeate produced and fluxes achieved for 2 different samples of effluent. The effect of cleaning on membrane performance was assessed. A reusability test was carried out on both permeate samples for dyeing light and dark shade recipes. The use of UF as pre-treatment to NF resulted in rejection of colloidal substances > 90% and a 15% flux improvement. Permeate from NF90 had a conductivity of 76 µS/cm and total organic carbon (TOC) of 20 mg/ℓ, as compared to SR90 which had a conductivity of 8.3 mS/cm and a TOC of 58 mg/ℓ. Light shade from NF90 gave satisfactory results on dyeing, with no colour difference. However a variation in colour was noticed when the medium sample was used to dye the light shade. Both NF permeates gave satisfactory results when used to dye the dark shades. Permeate from NF90 was within the accepted range for reuse, while permeate from SR90 had a higher salt recovery. Chemical cleaning resulted in 80% flux recovery. From the reusability test it was concluded that permeate from NF90 met the reuse criteria for feed water to the dye bath.