Research Publications (Water and Wastewater Technology)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/841
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Item A review on conventional and novel adsorbents to boost the sorption capacity of heavy metals : current status, challenges and future outlook(Informa UK Limited, 2024-12-31) Kumar, Arvind; Indhur, Riona; Sheik, Abdul Gaffar; Krishna, Suresh Babu Naidu; Kumari, Sheena; Bux, FaizalABSTRACT Heavy metal contamination in aquatic environments has attracted global concern due to its detrimental impact on living organisms, including toxicity and carcinogenicity. Therefore, initiatives to remove these contaminants from wastewater to protect both the environment and the well-being of humans is imperative. Materials utilized for wastewater treatment in the developing world needs to satisfy the main criterion of being locally available, inexpensive and that do not require additional energy input or modifications. Adsorption is the foremost used technique to eliminate heavy metals due to its attractive features including flexible design, operation, and cost-effectiveness. This review article potentially focusses on the use of novel and conventional adsorbents such as g-C3N4, graphene, cellulosic aerogel, natural occurring soil and minerals, aquatic and terrestrial biomass-based adsorbents for heavy metal adsorption, whilst focusing the discussion on the context of the developing world. This heightened interest in g-C3N4, and graphene-based adsorbents owes their unique properties such as great surface area, impressive chemical and thermal stability, three-dimensional structure, and functionalized derivatives which have shown great adsorption capabilities for heavy metals elimination. Additionally, cellulosic aerogel, natural occurring soil and minerals, aquatic and terrestrial biomass is low cost, easily available and effectively removes heavy metals. Finally, current progress, major challenges and future outlook of novel and conventional adsorbent materials for heavy metal removal are discussed. Herein a roadmap is presented together with recommendations for future research to enhance the successful utilization of bio-sorbents in water purification systems such as wastewater treatment plants.Item Digitalization of phosphorous removal process in biological wastewater treatment systems : challenges, and way forward(Elsevier BV, 2024-05-10) Sheik, Abdul Gaffar; Krishna, Suresh Babu Naidu; Patnaik, Reeza; Ambati, Seshagiri Rao; Bux, Faizal; Kumari, Sheena K.Phosphorus in wastewater poses a significant environmental threat, leading to water pollution and eutrophication. However, it plays a crucial role in the water-energy-resource recovery-environment (WERE) nexus. Recovering Phosphorus from wastewater can close the phosphorus loop, supporting circular economy principles by reusing it as fertilizer or in industrial applications. Despite the recognized importance of phosphorus recovery, there is a lack of analysis of the cyber-physical framework concerning the WERE nexus. Advanced methods like automatic control, optimal process technologies, artificial intelligence (AI), and life cycle assessment (LCA) have emerged to enhance wastewater treatment plants (WWTPs) operations focusing on improving effluent quality, energy efficiency, resource recovery, and reducing greenhouse gas (GHG) emissions. Providing insights into implementing modeling and simulation platforms, control, and optimization systems for Phosphorus recovery in WERE (P-WERE) in WWTPs is extremely important in WWTPs. This review highlights the valuable applications of AI algorithms, such as machine learning, deep learning, and explainable AI, for predicting phosphorus (P) dynamics in WWTPs. It emphasizes the importance of using AI to analyze microbial communities and optimize WWTPs for different various objectives. Additionally, it discusses the benefits of integrating mechanistic and data-driven models into plant-wide frameworks, which can enhance GHG simulation and enable simultaneous nitrogen (N) and Phosphorus (P) removal. The review underscores the significance of prioritizing recovery actions to redirect Phosphorus from effluent to reusable products for future considerations.Item Nanoclay-based conductive and electromagnetic interference shielding properties of silver-decorated polyaniline and its nanocomposites(Royal Society of Chemistry (RSC), 2023-01-01) Moolemane, Revanasiddappa; Nayak, Haridasa; Marudhachalam, Naveen; Coimbatore Venkatasubramanian, Anantha Krishnan; Arunachalam Chandra, Anirudh Raj; Murugappan Iyyappan, Arun; Krishna, Suresh Babu NaiduPolymer composite materials have seen rapid growth in popularity over the past two decades due to their ability to successfully combine the benefits of several different polymer composites into a single product. Conducting polymers (CPs) are more promising materials than other polymers due to their diverse electronic applications, including electromagnetic interference (EMI) shielding, light-emitting diodes, energy storage devices, and the most sophisticated forms of sensors. In this study, the effect of nanoclay on the electrical conductivity, humidity, and EMI shielding properties of silver-decorated polyaniline and its nanocomposites has been investigated. Silver-decorated polyaniline was prepared by using an in situ polymerization technique at 0–5 1C in the presence of ammonium persulphate, which acts as an oxidizing agent. Varied weight% amounts of nano clay were mixed in the conducting silver decorated polyaniline to obtain their nanocomposite. The synthesized silver-decorated polyaniline and its composites were characterized by using several physical methods, viz., Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). All these spectral data reveal the structural characteristics, morphology, and uniform distribution of silver and nano clay particles in the conducting polymer composites. The AC electrical conductivity data show that increasing the nanocrystal weight percentage increases its electrical conductivity. The electromagnetic interference shielding effectiveness of silver-decorated polyaniline nano clay composites shows 90% attenuation between 5 and 8.5 dB. Humidity sensitivity showed a linear relationship with increasing nano clay weight in the decorated polyaniline due to the porosity of the nanoclays and specific adsorption of moisture content. Hence, these composites can be used as a promising material for humid sensors, EMI shielding, battery capacitors, and other technological applications.Item Green synthesis, characterization and biological activities of silver nanoparticles synthesized from Neolamarkia cadamba(International Association of Physical Chemists (IAPC), 2023-07-01) Maheswari, Juluri; Anjum, Mohammed Reshma; Sankari, Mohan; Narasimha, Golla; Krishna, Suresh Babu Naidu; Kishori, BattiniBackground and purpose: Metal nanoparticles are essential due to their unique catalytic, electrical, magnetic, and optical characteristics, as well as their prospective use in sensing, catalysis, and biological research. In recent years, researchers have focused on developing cost-effective and eco-friendly biogenic practices using the green synthesis of metal nanoparticles (AgNP). Experimental approach: In the present study, the aqueous extracts prepared from the leaf, stem, bark, and flower of Neolamarkia cadamba were used for the synthesis of silver nanoparticles. Synthesized silver nanoparticles were characterized using UV-Visible spectroscopy, zeta potential, dynamic light scattering, scanning electron microscope (SEM), and EDAX. Key results: The current study showed absorption of synthesized AgNPs at 425, 423, 410, and 400 nm. Dynamic light scattering of AgNPs Showed size distribution of AgNPs synthesized from leaf, stem, and flower aqueous extracts ranges from 80-200 nm and AgNPs prepared from bark extract ranges from 100-700 nm. Zeta-potential of the biosynthesized AgNPs was found as a sharp peak at -23.1 mV for the leaf, -27.0 mV for the stem, -34.1 mV for the bark, and -20.2 mV for the flower. Silver nanoparticles and crude extracts of Neolamarkia cadamba showed effective antibacterial, antifungal, and antioxidant activities. Conclusion: Silver nanoparticles have substantial antibacterial activity against Gram-positive bacteria and also exhibit the utmost antifungal activity against Aspergillus niger. The study concludes that the green synthesis of silver nanoparticles from N. cadamba leaf, stem, bark, and flower extract is a reliable and eco-friendly technique.Item Mechanistic insight into SO4•−/•OH radical for enhancing stability and activity of LaMO3 perovskite toward detoxification of bulk pharmaceutical wastewater: Stoichiometric efficiency and controlled leaching study(Elsevier BV, 2023-08) Kumar, Arvind; Prasad, Basheswar; Kumari, Sheena; Bux, FaizalThis study aims to investigate the detoxification of real pharmaceutical manufacturing wastewater by PMS activated with perovskite LaMO3 (M = Cu, Co, Fe), synthesized by citric sol–gel method. The textural properties of synthesized perovskite were monitored by BET, FESEM/EDS, TEM, XRD, FTIR, and XPS techniques. The effects of key parameters (PMS dose, catalyst, pH and reaction temperature) on ofloxacin degradation along with PMS utilization efficiency as well as PMS consumption were evaluated in detail. Catalyst LaCoO3 exhibited the excellent catalytic activity and stability towards the degradation of ofloxacin (97.11 %) and COD (79.41 %) at optimum operating conditions. Removal of ofloxacin and COD were suppressed by 7 % and 9 % over the fourth cycle, along with minor leaching of Co were observed. Quenching experiments and EPR results demonstrated that both ROS species (SO4•− and •OH) were dominant species for ofloxacin degradation in LaCoO3/PMS system. The treatment cost for ofloxacin degradation in LaCoO3/PMS system was estimated to be 40.78$/m3 of real pharmaceutical wastewater. Six plausible degradation pathways of ofloxacin were proposed based on intermediate compounds identified by GC-MS and reported literature.Item Water quality modelling to assess sources and transport of pathogens within uMsunduzi catchment, South Africa(2022-05) Ngubane, Zesizwe; Bergion, Viktor; Dzwairo, Bloodless; Troell, Karin; Amoah, Isaac; Stenström, Thor Axel; Sokolova, EkaterinaWater quality modelling is essential to integrated water resources management and decision-making, as it improves the understanding of the spatial and temporal dynamics of chemical and microbial pollution in a river system. Understanding of the spatio-temporal dynamics of pollution and accurate prediction of its pollution hotspots are vital to improving the microbial quality of surface water. South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among rivers with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Escherichia coli (E. coli) and Cryptosporidium, chosen to represent bacteria and protozoan parasites respectively, this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT) model. SWAT uses a combination of empirical and physically based equations that use readily available inputs and enables users to study long term impacts. Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R2 of 0.64 and 0.58, respectively. The SWAT module for predicting microorganism loads and concentrations in the river was used. The main faecal sources in the uMsunduzi catchment can be summarised as: wastewater treatment plant (WWTP), broken sewers in the urban area, and faecal droppings from grazing livestock. The microorganism loads from these sources were described in SWAT using data from different local water authorities and stakeholders. With respect to E. coli, the output from SWAT was compared to observed data from four points within the catchment representing upper rural, upper urban, lower urban, and lower rural parts. The output from the SWAT model showed slightly low variability, however, the trend in the SWAT model simulations followed the observed data patterns in most subbasins. The trend with Cryptosporidium was such that concentrations are higher downstream the WWTP than upstream, though insufficient data exists to compare the model Cryptosporidium output with observed data. Overall, the model microbial output showed that in rural areas, animals contribute more to pathogen loads than human sources. Human sources were more prominent in urban areas owing to the major contributions from wastewater infrastructure. The microbial output data from the SWAT model were used as input for quantitative microbial risk assessment (QMRA). Considering that not all E. coli are pathogenic, 8% of E. coli was assumed as pathogenic following various studies. The exposure routes investigated were direct ingestion of the uMsunduzi River water during recreational swimming, canoeing training, and drinking. The exposed population was categorised as children (<18 years old) and adults (>18 years old). The probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines and by the World Health Organisation (WHO).The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.