Environmental Technology Reviews

Anang, Emmanuella; Hong, Liu; Fan, Xianyuan; Asamoah, Ebenezer Nestle

doi: 10.1080/21622515.2021.2010131pmid: N/A

Polluted water continues to be a major problem globally since it deteriorates human health after consumption and impedes sustainable development. Nanoscale zero-valent iron (nZVI) has been used to tackle the problem, but certain significant disadvantages of the nZVI limit its efficiency. Owing to the demerits of nZVI, various materials have been employed to support the nZVI to ensure efficient decontamination. There is rising interest in using attapulgite as a support for nZVI. The use of attapulgite supported nanoscale zero-valent iron (A-nZVI) to decontaminate wastewater/groundwater has proven to be highly efficient as compared to unsupported nZVI. This paper presents an overview of the syntheses, performance, application and limitations of using A-nZVI to treat wastewater/remediate groundwater. A-nZVI has been extensively employed on laboratory scale, thus making it difficult to simulate its removal efficiency on a large scale. However, its high removal efficiency under the appropriate operational conditions make it ideal to be used on an industrial level. This review is important because it identifies gaps in literature with respect to A-nZVI that need to be filled to improve ZVI-based technology.

Misra, Modhurima; Chattopadhyay, Soham; Sachan, Ashish; Sachan, Shashwati Ghosh

doi: 10.1080/21622515.2021.2011431pmid: N/A

Rapid urbanization and development of industries have led to the continuous addition of various wastes and hazardous chemicals into the environment, thus polluting it beyond limits. It is an issue of global concern as coming up with effective methods for remediation has become a challenge. The traditional methods for pollutant removal face serious drawbacks in terms of cost and generation of secondary pollutants, thus innovating simple and environment-friendly approaches becomes a priority. New technologies are being explored for the eradication of different contaminants, of which nanotechnology has shown immense potential. Biogenic nanoparticles are synthesized using different microbes and are further employed for the remediation of environmental pollutants. Complete degradation of Methylene Blue within 11 min and 98% degradation of Congo Red after 20 min were accomplished using gold nanoparticles, synthesized using cell-free extracts of Bacillus marisflavi in a recent study. Palladium nanoparticles, synthesized using Shewanella loihica PV-4 and Enterococcus faecalis, facilitated the complete reduction of toxic hexavalent chromium. This review focuses on microbe-mediated synthesis of nanomaterials and their prospect in the field of environmental remediation.

Devahi, P.; Rathod, Deendayal; Muthukkumaran, K.

doi: 10.1080/21622515.2021.2024890pmid: N/A

The practice of manufacturing building materials using solid waste incineration ash provides an excellent avenue for reducing the drastic amount of volume entering the waste stream. Further, it curtails the replenishment of naturally available resources, thereby guaranteeing the management of carbon footprint in the construction industry. This paper reviews the broad spectrum of building material applications made possible from municipal solid waste incineration ash. Attention was given to the minerals responsible for their beneficial outputs and their chemical composition, followed by analyzing their strength performance. This manuscript will also act as a guideline for utilizing incineration ash by highlighting its engineering application at a definite proportion. It also highlights the influence of thermal treatment and geopolymer incorporation for strength enhancement in building elements. Furthermore, a brief conclusion elaborates the crucial need in identifying future research and development, focusing mainly on the advancement of material usage in the building industry.

García-Ávila, Fernando; Zhindón-Arévalo, César; Valdiviezo-Gonzales, Lorgio; Cadme-Galabay, Manuel; Gutiérrez-Ortega, Horacio; del Pino, Lisveth Flores

doi: 10.1080/21622515.2021.2013955pmid: N/A

This study compares the Canadian Council Water Quality Index (CCME WQI) and the Arithmetic Water Quality Index (WAWQI) methodologies for determining the quality of water in the city of Azogues (Ecuador). Additionally, a drinking water quality risk index (IRCA) was determined to evaluate the degree of risk of disease occurrence related to water consumption. The data generated came from the analyses of twelve physicochemical parameters (pH, turbidity, colour, total dissolved solids, electrical conductivity, total hardness, alkalinity, nitrates, phosphates, sulfates, chlorides, residual chlorine) from 172 samples of water over six months. The calculated average value of CCME WQI (97.59 ± 1.08) indicates that 100% of the drinking system was of ‘excellent’ quality. The WAWQI average value was calculated to be 26.36 ± 1.13 indicating that 16.67% of the distribution system was of ‘excellent’ quality and 83.33% of the distribution water was of ‘good’ quality. The IRCA calculated in all the distribution zones is between 0 and 5% and therefore, the distributed water is considered suitable for human consumption and is rated at the no-risk level. Furthermore, WAWQI is influenced by parameters with low maximum allowed concentration (for example, turbidity value 1 NTU in the Ecuadorian standard was used instead of 5 NTU recommended by the WHO); conversely, CCME-WQI is influenced by parameters with a high maximum allowed concentration (no parameter exceeded the norm in this study). The IRCA is a support instrument to guarantee that the water supplied by the provider companies complies with the characteristics established for drinking water.

Zhou, Quan; Le, Quyet Van; Meng, Lingbo; Yang, Han; Gu, Haiping; Yang, Yafeng; Chen, Xiangmeng; Lam, Su Shiung; Sonne, Christian; Peng, Wanxi

doi: 10.1080/21622515.2021.2017000pmid: N/A

The environmental concerns caused by textile waste require technological development to support recycling and re-utilization. Incineration and landfill of textile waste are still widely used, and they lead to soil and water pollution as well as emissions of greenhouse gases. Recently, various research studies on textile waste treatment try to find appropriate technical means to realize environmental protection and sustainable recycling. Here, we summarize and discuss new ways to improve the treatment of textile waste, including its utilization value and transformation ways, to help remediation and lower environmental impacts. This paper comprehensively expounds on the current situation of textile waste treatment and the recycling value of different types of textile waste. This includes recycling composite materials, fillers, energy materials and carbonized adsorption material, which support sustainable development with social and economic benefits. Overall, this shows that textile waste needs to be separated at large scales globally to reduce the carbon footprint, improve socio-economic benefits and mitigate environmental pollution. Otherwise, there is a risk that the global warming and ecosystem transformations, due to pollution and urbanization, could lead to severe adverse effects such as cancer and global pandemics.

Zafar, Hirra; Peleato, Nicolas; Roberts, Deborah

doi: 10.1080/21622515.2022.2058426pmid: N/A

Food waste is primarily managed by incineration or disposal in landfills. These current management methods can result in adverse environmental effects, are expensive, and do not necessarily take advantage of the remaining energy potential in food waste. Alternative treatment technologies such as microbial fuel cells (MFCs) are an attractive disposal method since overall organic concentrations can be reduced, and some of the chemical energy of the food waste can be transformed into electrical energy. MFC research has focused on the use of liquid waste due to advantages such as easy handling, low internal resistance, and efficiency of ion transfer in the liquid phase. While some researchers have shown the potential of using complex solid waste as a direct fuel in MFC, there remain significant challenges for optimizing complex solid food waste-fed MFCs. In particular, the biological degradation of the complex substrates in food waste is a slow process and requires additional pre-treatment (physical, thermal, chemical, or biological) to degrade complex biopolymers efficiently. As such, this article aims to review the impact and importance of various pre-treatment methods for optimizing performance of food waste fed MFCs. It is clear that direct use of solid waste in MFCs can be promising if several factors are optimized, including the pre-treatment used, substrate biodegradability, and operational cost. Although low power output is one of the main obstacles in the commercialization of MFC, MFC can still be considered a viable, self-sufficient treatment method to treat waste with minimum to zero emissions.

Nathan, Risha Jasmine; Jain, Arvind Kumar; Rosengren, Rhonda J.

doi: 10.1080/21622515.2022.2078232pmid: N/A

The presence of heavy metals in drinking water is a serious global issue. Sustainable methods for treating drinking water such as biosorption are gaining popularity. The maximum permissible limits of most metal ions in drinking water are in the range from 0.003 to 2 mgL−1, however, the elevated concentrations in the range 0.01–2.5 mgL−1 are reported in contaminated waters in various regions of the world. Therefore, selecting the initial metal ion concentration range, and an optimum pH suitable for treating drinking water (pH 6.5–8.5) for laboratory experiments is a challenge for multi-ion biosorption studies. For the quantification of metal ions, ICP-MS is often used owing to its many advantages, however, the high operational costs of this instrument limits its use in research laboratories. Surface characterisation techniques such as TEM, NMR, ESR and related techniques are often ignored in biosorption studies although, these give valuable information pertaining to the mechanism of biosorption. Many theoretical models for explaining the biosorption mechanism have been proposed in the literature, one often contradicting the other. One of the major drawbacks of published biosorption studies is that too much emphasis has been laid on the theoretical explanation of biosorption mechanism and too little has been done to address the lack of practical application in terms of translatability of the methodology for commercial use. The present review highlights such issues while giving an insight on the processes, parameters and models used in biosorption reactions.

Ortiz-Lopez, Christian; Bouchard, Christian; Rodriguez, Manuel

doi: 10.1080/21622515.2022.2118084pmid: N/A

Modelling source water quality in drinking water treatment systems could be useful for anticipating changes in specific raw water quality parameters. Those changes entail adjustments in drinking water treatment plant (DWTP) operations. Artificial intelligence (AI) has been used for modelling water quality for different purposes and has yielded reliable results. However, there has not yet been wide investigation of raw water quality modelling for treatment purposes using AI. For the first time, in this critical review, we analyzed AI models founded on machine learning techniques that are used for surface water quality modelling and which could be applied in the domain of source water treatment. In a novel approach, we convened an expert panel that helped us define the appropriate criteria for use in the selection of the papers for review. We analysed the selected papers according to several criteria, including the feasibility of input data generation, the modelled data applicability and the benefits and limitations. We evaluated whether the selected models could be applied to forecast raw water quality as decision support systems (DSS) in drinking water treatment. The highest rated were turbidity hourly models based on Support Vector Machines (SVM), as well as daily turbidity and pH models based on Artificial Neural Networks (ANN). We found there is a shortage of models used to specifically estimate raw water quality, which could assist in DSS at DWTPs. There should be an increased effort to model raw water quality, especially with AI models using hourly and sub-hourly time step.

Avşar, Cemre; Tümük, Didem; Yüzbaşıoğlu, Abdullah Emre; Gezerman, Ahmet Ozan

doi: 10.1080/21622515.2022.2119171pmid: N/A

Greenhouse gas emissions, mostly CO2 release, on anthropogenic sources and industrial applications have triggered an increase in global temperature, termed as global warming and as-related climate change. Phosphogypsum (PG) is a by-product of wet process phosphoric acid production, mainly composed of calcium sulfate dihydrate (gypsum) together with some impurities. The annual accumulation rate of PG has reached 300 Mtons, and there is a need for an efficient, continuous, and bulk consumption strategy. Industrial by-products have been used as an alternative raw material for CO2 capture as a solid carbonate compound. PG is rich in calcium, being a promising candidate for CO2 mineral sequestration. In this manner, the Merseburg process (the ammono-carbonation of gypsum) allows both CO2 capture and PG recycling. Products are ammonium sulfate, a well-desired nitrogenous fertilizer and CaCO3, a functional filler material utilized in various kinds of industries. The Merseburg process allows dual environmental benefits by allowing the consumption of an industrial by-product and performing CO2 capture technology, both contributing to sustainable development goals. This study gives a brief summary of the environmental possible impacts of the Merseburg process in terms of CO2 sequestration and phosphogypsum management.

Rossi, Elena; Pecorini, Isabella; Panico, Antonio; Iannelli, Renato

doi: 10.1080/21622515.2022.2139641pmid: N/A

In the last decades, the worldwide interest in volatile fatty acids (VFAs) as basic elements for many industrial applications has been growing as fast as their market demand. Traditional production of VFAs from crude oil is unsustainable because of its environmental impact, therefore alternative solutions have been studied. The most promising solution has resulted in the VFAs production from organic waste based on biological processes thanks to the incoming environmental and economic benefits. In this scientific context, the state of current knowledge has not reached yet a satisfying level of comprehensiveness and it is mainly based on studies conducted at lab and pilot scale. Under the perspective to gain more knowledge and thus to promote an efficient as well as consolidated production of VFAs according to the key issues of the circular economy, a systematic and detailed study dealing with the impact of reactor configuration and relative operating conditions on biological VFAs production has been conducted. This step is a necessary condition to scale up the process and achieve its complete industrialization. According to this perspective and on the basis of the most recent findings from the international literature, the present review paper reports, as the main result of data elaboration, a novel one-to-one correspondence between organic wastes and reactor configurations having as target the VFAs yield enhancement.