Article
Engineering, Environmental
Hui Wang, Wenzong Liu, Muhammad Rizwan Haider, Feng Ju, Zhe Yu, Yingjun Shi, Weiwei Cai, Aijie Wang
Summary: The study proved the effectiveness of an integrated strategy combining pretreatment with microbial electrolysis-assisted anaerobic digestion system for sludge lysate treatment and resource recovery. The pretreatment enhanced the biodegradation and bio-transformation of organic compounds, while membrane separation improved methane yield and purity, as well as protein recovery. This strategy shows potential for widespread adoption in wastewater treatment plants for sludge lysate treatment and sustainable resource recovery.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
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)
Review
Engineering, Environmental
Qian Zeng, Hao Huang, Yunkai Tan, Guanghao Chen, Tianwei Hao
Summary: This paper critically reviews the versatile uses of electrochemical processes for sludge treatment and resource recovery, discusses the working mechanisms, and proposes future research directions.
Article
Engineering, Environmental
Zhihong Liu, Xiaoyun Yin, Bingjie Ni, Xi Chen, Fei Xie, Zhengtong Guo, Dengfei Li, Wenzong Liu, Xiuping Yue, Aijuan Zhou
Summary: This study investigates the impact of different iron sources on the recovery of hydrogen and vivianite from waste biomass. The results show that the Fe anode group achieves the highest hydrogen productivity and the highest efficiency of short-chain fatty acids utilization and phosphate removal. Additionally, electrochemically active bacteria play an important role in the recovery process.
CHEMICAL ENGINEERING JOURNAL
(2023)
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
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
Jie Liu, Zi Zhang, Weiqi Xue, Withanage B. Siriweera, Guanghao Chen, Di Wu
Summary: This study investigated a new bioresource technology for recovering raw chemicals of sulfated polysaccharides (SPs) from digested saline waste activated sludge. The extracted SPs were proven to be high purity (>80%) and had significant properties such as anti-inflammation, anti-oxidation, and anti-coagulation for potential pharmaceutical-like application.
BIORESOURCE TECHNOLOGY
(2021)
Article
Environmental Sciences
Mei Zou, Mengyu Yin, Yayi Yuan, Dongbo Wang, Weiping Xiong, Xiao Yang, Yaoyu Zhou, Hongbo Chen
Summary: Triclosan promotes volatile fatty acid accumulation in waste activated sludge anaerobic fermentation, accelerating acid production and enhancing key enzyme activity.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Environmental Sciences
Cong Zhang, Peng Hu, Qing Liu, Zeyu Lu, Benyi Cao, Yuxin Tang, Tianwei Hao
Summary: This study extracted alginate-like exopolysaccharides from activated sludge and used it as a novel biopolymer agent for crack self-healing in mortar. With 0.5 wt% addition of the exopolysaccharides, a high crack closure ratio of 86.5% was achieved within 28 days, with marginal reduction in flexural strength compared to commercial healing agents.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Green & Sustainable Science & Technology
Zheng Wu, Qi Zheng, Yibo Zhang, Yin Pang, Tao Huang, Daoping Peng
Summary: The recovery of phosphorus as vivianite from anaerobic digestion of waste-activated sludge has gained attention due to its high recovery efficiency and economic value. This study explores the use of magnetic biochar as an additive to enhance vivianite crystallization during the digestion process. The results show that the phosphorus recovery efficiency can reach 45% and methane yield can increase by 27% with the addition of magnetic biochar. The magnetic biochar also allows for easy separation of vivianite from the sludge.
JOURNAL OF CLEANER PRODUCTION
(2023)
Article
Agricultural Engineering
Najiaowa Yu, Huijuan Sun, Anqi Mou, Yang Liu
Summary: The study demonstrated that pretreatment of WAS with Ca(ClO)2 significantly improved anaerobic digestibility and methane production. Low doses of Ca(ClO)2 enhanced digestion efficiency, while high doses reduced microbial activities and prolonged methane production lag phase.
BIORESOURCE TECHNOLOGY
(2021)
Article
Engineering, Environmental
Suo Xiao, Bryen Woo, Ames Goldhardt, Lu-Kwang Ju
Summary: Phagotrophic algae can consume bacteria in waste activated sludge, and a combined ultrasonication-phagotrophic algal process can reduce sludge VS significantly. The process requires lower energy consumption and produces microalgae for other potential uses, making sludge management more sustainable.
WATER ENVIRONMENT RESEARCH
(2021)
Article
Green & Sustainable Science & Technology
Zicong Liao, Yongyou Hu, Yuancai Chen, Jianhua Cheng
Summary: This study combined TAP treatment with struvite precipitation technology to enhance sludge dewaterability and phosphorus recovery, achieving resource utilization of waste activated sludge. TAP treatment effectively released phosphorus and nitrogen from sludge, while the income obtained from struvite precipitation covered the corresponding costs, demonstrating good economic benefits.
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
Mengge Tang, Yanxin Wu, Xingning Zeng, Xiao Yang, Dongbo Wang, Hongbo Chen
Summary: This study clarifies the promoting effect of residual antibiotic chlortetracycline on the anaerobic fermentation of waste activated sludge to produce volatile fatty acids. Mechanistically, the study shows that the antibiotic enhances VFA production by prompting the secretion of extracellular polymeric substances and stimulating acidification, while inhibiting methanogenesis. These findings provide new insights for resource recovery from WAS containing chlortetracycline.
BIORESOURCE TECHNOLOGY
(2021)
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
Green & Sustainable Science & Technology
Evans M. Nkhalambayausi Chirwa, Tshilidzi B. Lutsinge-Nembudani, Oluwademilade M. Fayemiwo, Fisseha A. Bezza
Summary: The biomineralisation of PAHs to CO2 and H2O is an environmentally friendly and economically efficient option for treating deleterious organic pollutants in water and soil. Experimental results showed a significant improvement in the removal of PAHs in the biofilm reactor system, with the predominant microbial agents being Pseudomonas aeruginosa MS-1 and Acinetobacter species.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Environmental Sciences
Wan Azlina Ahmad, Chidambaran Kulandaisamy Venil, Evans M. Nkhalambayausi Chirwa, Yi-Tin Wang, Mohd Helmi Sani, Abdul Fatah A. Samad, Mohd Farizal Ahmad Kamaroddin, Edgardo R. Donati, Maria Sofia Urbieta, Zainul Akmar Zakaria
Summary: The review discusses the significance of hexavalent and trivalent chromium compounds, the challenges of current Cr(VI) treatment techniques, and the feasibility of biological processes for Cr(VI) reduction in industrial effluents. It also highlights the cytotoxicity and genotoxicity of Cr(VI), recent findings in bacterial reduction of Cr(VI), operational challenges, and examples of laboratory-scale and pilot-scale evaluations.
CURRENT POLLUTION REPORTS
(2021)
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)
