Article
Agriculture, Multidisciplinary
A. Brai, C. Vagaggini, C. Pasqualini, F. Poggialini, F. Tarchi, V. Francardi, E. Dreassi
Summary: This study demonstrates that distillery by-products contain abundant antioxidant compounds and beneficial fatty acids even after processing. Using them as feed for Tenebrio molitor larvae not only increases the average weight gain of the larvae but also has no effect on their survival rate. Furthermore, the use of these by-products can enhance the total antioxidant activity and improve the nutraceutical properties of the larvae.
JOURNAL OF INSECTS AS FOOD AND FEED
(2023)
Article
Energy & Fuels
Haixia Du, Zongping Shao
Summary: Microbial fuel cells (MFCs) are an attractive technology for converting organic waste into electrical power. This study investigated the impact of mixing solid potato waste (SPW) and waste activated sludge (WAS) to enhance waste-to-power conversion in MFCs. The results showed that a mixing ratio of 6:1 between SPW and WAS produced the highest current and power densities. Mixing smaller ratios of WAS significantly increased the coulombic efficiency. The study provides a promising strategy for enhancing energy recovery from SPW in MFCs.
Article
Agricultural Engineering
Zhetai Hu, Weiwei Li, Haoran Duan, Xin Huang, Jia Meng, Liangzhen Yang, Min Zheng
Summary: This study proposed an integrated approach to efficiently recover phosphorus (P) as vivianite from waste activated sludge (WAS) and simultaneously enhance sludge dewaterability. Acidification and Fe3+ reduction were conducted to convert Fe and P from solid phase to liquid phase. Acid-elutriation technology was then introduced to enhance liquor-solid separation. Finally, vivianite was obtained via sludge eluate neutralization. The enhanced sludge dewaterability not only increases the recovery efficiency of Fe and P but also decreases the cost of sludge disposal.
BIORESOURCE TECHNOLOGY
(2023)
Article
Energy & Fuels
Uday Jhunjhunwala, Susant Kumar Padhi, Lopa Pattanaik, Dhruv Sharma, Abhishek Kumar, Pallavi Chaudhary, Vikalp Saxena
Summary: This study evaluated the anaerobic co-digestion of food waste and waste activated sludge in batch reactors and determined the optimal ratio using the biochemical methane potential test. The ratio of food waste to microorganism was maintained at 2, and the result showed that a 50:50% ratio in one reactor yielded the highest methane production. The digestate sludge from this reactor showed potential as a biofertilizer, and the liquid digestate generated served as a valuable source of liquid fertilizer.
BIOMASS CONVERSION AND BIOREFINERY
(2023)
Article
Engineering, Environmental
Seth Apollo, Manana Seretlo, John Kabuba
Summary: This study presents the performance of a modified AS system, known as the SPRAS process, which achieved significant sludge reduction through in situ cell lysis. The SPRAS plant had a sludge yield of 0.0823 kg TSS/kg COD, much lower than the conventional activated sludge process. The process demonstrated adequate sludge settling ability and achieved high reductions in ammonia and COD.
JOURNAL OF WATER PROCESS ENGINEERING
(2023)
Article
Engineering, Chemical
Xiawen Yi, Huihui Zhong, Ming Xie, Pin Zhao, Weilong Song, Xinhua Wang
Summary: The fouling behaviors and mechanisms of forward osmosis (FO) membrane in sludge thickening (FO-MST) process were investigated. Results showed that sludge concentration had a significant impact on FO membrane fouling, which could be divided into three stages.
JOURNAL OF MEMBRANE SCIENCE
(2022)
Article
Environmental Sciences
Yun Wang, Wei Wei, Xiaohu Dai, Bing-Jie Ni
Summary: The study proposed a green method using corncob ash to enhance hydrogen production during anaerobic fermentation of waste activated sludge. Corncob ash dosage positively correlated with hydrogen production, reaching up to 46.8 +/- 1.0 mL/g VS. Mechanistic studies showed benefits in solubilization, hydrolysis, and acetogenesis processes.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Environmental Sciences
Mojca Zupanc, Barbara Brajer Humar, Matevz Dular, Jurij Gostis, Marko Hocevar, Sabina Kolbl Repinc, Mario Krzyk, Lovrenc Novak, Jernej Ortar, Ziga Pandur, Blaz Stres, Martin Petkovsek
Summary: Anaerobic digestion in wastewater treatment plants can convert waste activated sludge into biogas. Pre-treatment of the sludge can further improve the efficiency and increase methane production. Different cavitation regimes have different effects on the physical and chemical properties of the sludge samples. While methane production increased, the energy consumption efficiency was not particularly high.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2023)
Article
Engineering, Environmental
Shuaishuai Li, Yuling Liu, Chuanchuan Dou, Ruihao Sun
Summary: This study explores the pretreatment of sludge using thermally activated sodium persulfate-biochar skeleton to improve its dewaterability. It demonstrates that under optimal conditions, the water content of waste activated sludge can be significantly reduced while capillary suction time and specific resistance to filtration are improved. The study proposes a relationship between organic matter migration and sludge physical structure and elucidates the mechanism behind the improvement in dewaterability.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Multidisciplinary Sciences
Yi Rong, Hongjun Tang, Yang Zhang, Yingying Sun, Zhe Liu
Summary: With rapid economic development and urbanization in China, rural wastewater treatment has become a pressing issue. This study investigated the quality and discharge characteristics of rural sewage in Shaanxi, China, and found that the biodegradability of rural wastewater is adequate for biological treatment. However, the intermittent flow cut-off characteristics of sewage in treatment stations lead to poor pollutant removal efficiency. The study proposed a biologically enhanced internal circulation treatment system, which showed stable removal effects on nitrogen and phosphorus.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Environmental
Xiawen Yi, Huihui Zhong, Ming Xie, Xinhua Wang
Summary: The MF-FO reactor achieved a thickening of MLSS concentration to 50 g/L after 10 days, with superior effluent quality.
Article
Environmental Sciences
Lindsey Woolley, Md Reaz Chaklader, Luke Pilmer, Frances Stephens, Catherine Wingate, Michael Salini, Gavin Partridge
Summary: Methanotrophic bacteria can convert methane into highly nutritious single-cell protein (SCP), which can replace fishmeal and improve the growth and feed conversion efficiency of barramundi. The inclusion of SCP in the diet supports gut health and shows potential for sustainable aquaculture.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Green & Sustainable Science & Technology
Phuong Linh Ngo, Brent R. Young, Kevan Brian, Saeid Baroutian
Summary: In this study, the pre-treatment of mixed sludge using thermal hydrolysis was investigated. It was found that the condition of thermal hydrolysis at 145 degrees C for 30 min provided the highest biogas production, without increasing the concentration of free ammonia. This condition also resulted in the highest amount of acetic acid and the lowest level of propionic acid, making it the most suitable condition for anaerobic digestion.
JOURNAL OF CLEANER PRODUCTION
(2023)
Article
Engineering, Environmental
Wenlong Hui, Jiti Zhou, Ruofei Jin
Summary: This study used thermal alkaline treatment (TAH) to extract proteins from waste activated sludge (WAS) and optimized the extraction conditions. It was found that during the TAH process, macromolecular proteins were broken down into low molecular proteins and produced less melanoid. XRD and XPS analysis suggested the formation of calcium carbonate (CaCO3) at pH 13 and temperature of 70 degrees C. The extracted sludge proteins had a relative molecular weight between 6.5 kDa and 16 kDa. Further research is needed for complete purification of the proteins.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2022)
Article
Agricultural Engineering
Xiaodi Li, Bo Wang, Yuqing Ma, Tan Jiang, Yongzhen Peng
Summary: This study investigated the reduction of nitrate in waste activated sludge fermentation and found that nitrate promoted the release of organic matter in sludge and enhanced its biodegradability. The destruction of volatile suspended solids was increased significantly in the presence of nitrate. Nitrate reduction also promoted sludge hydrolysis and acetogenesis, but slightly inhibited acidogenesis. This study provides a feasible method to address the overabundance of waste activated sludge and the lack of carbon sources in the denitrification process.
BIORESOURCE TECHNOLOGY
(2023)
Article
Electrochemistry
Mpumelelo T. Matsena, Shepherd M. Tichapondwa, Evans M. N. Chirwa
Summary: In this study, an environmentally friendly process for the treatment of Cr(VI) was explored using a microbial fuel cell with zero-valent palladium co-deposited on the anode electrode. By optimizing temperature, pH, initial Cr(VI) concentration, and the particle size of granular activated carbon (GAC), the performance of Cr(VI)-reducing MFC was significantly improved.
ELECTROCHIMICA ACTA
(2021)
Article
Chemistry, Physical
Buyisile Kholisa, Mpumelelo Matsena, Evans M. N. Chirwa
Summary: This study isolated and identified a microbial consortium culture from sludge in a wastewater treatment plant, showing strong reduction capability for Cr(VI) and high removal efficiency under various operational conditions. The results demonstrated the potential of using bacteria for hexavalent chromium remediation in contaminated sites.
Article
Chemistry, Physical
Job T. Tendenedzai, Evans M. N. Chirwa, Hendrik G. Brink
Summary: The study focused on the aerobic batch reduction of different selenite concentrations using Enterococcus spp. The results showed that Enterococcus species have high adaptability for rapid selenium reduction and biosynthesis of elemental selenium. The experimental data highlighted the potential of Enterococcus spp. for their ability to reduce selenite under extreme conditions.
Article
Environmental Sciences
Mpumelelo T. Matsena, Mziwenene Mabuse, Shepherd M. Tichapondwa, Evans M. N. Chirwa
Summary: The study demonstrates that optimizing the particle size of granular activated carbon (GAC) can enhance the performance and power output of microbial fuel cells (MFC), while different particle sizes have varying effects on MFC performance.
Article
Engineering, Chemical
Boitumelo F. Mashangoane, Evans N. Chirwa
Summary: Platinum group metals (PGMs) are elements that are concentrated in the earth's core and mantle, with low natural abundances. Due to their limited supply, there is economic value in recovering and reusing PGMs from waste solutions. Conventional methods for removing PGMs from wastewater have drawbacks, leading to a search for new technologies such as biosorption. This research project successfully developed a genetically modified strain of Saccharomyces cerevisiae EBY100 for biosorption of Pd (II) in aqueous solutions, with a maximum adsorption capacity of 125 mg/g.
MINERALS ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Job T. Tendenedzai, Evans M. N. Chirwa, Hendrik G. Brink
Summary: Research has shown that selenium oxyanions can be indirectly catalyzed to selenium nanoparticles by bacteria secreting metal-reducing metabolites. Using Enterococcus spp. cell-free extract, selenium nanoparticles were synthesized abiotically, exhibiting antimicrobial properties.
Article
Biochemistry & Molecular Biology
Olga Neveling, Thato M. C. Ncube, Ziyanda P. Ngxongo, Evans M. N. Chirwa, Hendrik G. Brink
Summary: This study aimed to determine the precipitation abilities of bacterial strains isolated from an industrially obtained Pb(II)-resistant microbial consortium. The results showed that Paraclostridium bifermentans and Klebsiella pneumoniae had different abilities to remove Pb(II) from solution, and they formed different precipitates.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Green & Sustainable Science & Technology
Englatina I. N. C. Assis, Brian Gidudu, Evans M. N. Chirwa, Jiri Jaromir Klemes
Summary: This study investigates the potential of hydrothermal carbonisation treatment for producing solid fuel from paper mill sludge. The results show that the properties of the hydrochar fuel can be influenced by process parameters such as temperature and reaction time. The produced hydrochars have low sulfur, nitrogen, and ash content and high calorific value. However, the substantial water demand is a drawback that needs to be addressed for industrial-scale application.
JOURNAL OF CLEANER PRODUCTION
(2022)
Review
Biochemistry & Molecular Biology
Brian Gidudu, Evans M. N. Chirwa
Summary: Electrokinetic remediation is a promising technology for remediating polluted environments. It utilizes five fundamental processes - electrolysis, electroosmosis, electrophoresis, diffusion, and electromigration - to achieve decontamination. To ensure sustainability, effective processes with low environmental impact and cleaner alternative solutions need to be pursued.
Article
Chemistry, Analytical
George Andrews, Olga Neveling, Dirk Johannes De Beer, Evans M. N. Chirwa, Hendrik G. Brink, Trudi-Heleen Joubert
Summary: The presence of lead in wastewater streams has adverse health effects. Conventional methods of lead recovery and removal have disadvantages. Klebsiella pneumoniae and Paraclostridium bifermentans have been identified as potential lead-precipitating species for use in a lead recovery bioreactor. Electrical impedance spectroscopy (EIS) on a low-cost device is used to monitor cell growth in the bioreactor. The study found a direct correlation between supercapacitance and colony-forming unit count, as well as a qualitative correlation between reactance elements and growth phase. Pb(II) ions act as an anaerobic respiration co-substrate and changes in plated count are mirrored in Pb(II) concentration. Guidance on the implementation of EIS devices for continuous impedance monitoring is provided.
Article
Environmental Sciences
Lesedi Kgatla, Brian Gidudu, Evans M. Nkhalambayausi Chirwa
Summary: The feasibility of augmenting the water harvesting potential of atmospheric water generators (AWGs) through the implementation of an evaporative cooling system (ECS) at the point of air extraction was investigated in this study. The results suggest that ECS does not significantly impact water yield, and capacity utilisation of the AWGs remains below 50% even after augmentation.
Article
Chemistry, Physical
Seshibe Makgato, Evans Nkhalambayausi-Chirwa
Summary: This study created a model to simulate the degradation of hazardous organic compounds in a combined chemical and biological treatment system. The kinetic parameters were evaluated and optimized, and new kinetic models were provided, contributing to a better understanding and utilization of the complex phenolic compounds' biodegradation processes.
Article
Chemistry, Physical
Fisseha A. Bezza, Samuel A. Iwarere, Shepherd M. Tichapondwa, Evans M. N. Chirwa
Summary: The scarcity of fresh water is a major threat to the modern world, exacerbating by rapid economic development and population growth. In this study, a 3D solar evaporator was fabricated and evaluated for its solar absorption potential, photothermal performance, and desalination potential. The 3D evaporator demonstrated efficient solar absorption, high photothermal conversion efficiency, and the potential to generate freshwater. The study highlights the promising potential of the 3D evaporator for real-world interfacial desalination, contributing to sustainable solutions for water shortage.
Article
Chemistry, Physical
Rachel Mugumo, Emmanuel Ichipi, Shepherd M. Tichapondwa, Evans M. Nkhalambayausi Chirwa
Summary: The aim of this study was to investigate a new combustion synthesis technique for creating CuS/ZnS p-n heterojunction nanocomposite photocatalysts and evaluate their photocatalytic activity and reusability in removing RhB dye under visible-light irradiation. Various characterisation methods were used to determine the properties of the materials, and the optimal photodegradation conditions were established by varying catalyst loading, pH level, and initial pollutant concentration. The results showed that a CuS/ZnS catalyst with a 10 g L-1 loading, at pH 5, degraded 97% of 5 ppm RhB dye after 270 min of visible light irradiation, and achieved 83% dye removal after five recycling runs. Scavenger tests identified h(+) and center dot O-2 as the primary reactive species responsible for degradation. This study provides valuable insights into the design of highly efficient nanomaterials for wastewater treatment.
Article
Green & Sustainable Science & Technology
Brian Gidudu, Evans M. N. Chirwa
Summary: This study evaluated the combination of bioremediation, biosurfactants, and electrokinetic remediation for the enhancement of petrochemical hydrocarbon removal from contaminated soil. The results showed that the biosurfactant did not inhibit bacterial growth but had an effect on root elongation and germination of plants. The optimum conditions for electrokinetic remediation were a voltage of 30 V, electrode spacing of 185 mm, and biosurfactant concentration of 84 g/L.
CLEANER ENGINEERING AND TECHNOLOGY
(2022)
