Treatment technologies for sustainable management of wastewater from iron and steel industry - a review

Insights into the potential of Chlorella species in the treatment of hazardous pollutants from industrial effluent

Effluents from the industrial sector contain a wide range of contaminants in the medium; when they are insufficiently treated and discharged in the aquatic environment, they pollute aquatic matrices, causing deleterious effects on all the lifeforms. Industries such as tanneries, textiles, dairy, pharmaceuticals, paper and pulp, food processing, petrochemicals, iron, and steel generate wastewater containing a wide range of environmentally harmful contaminants. Chlorella species are robust species that can adapt and grow in extreme conditions and have remarkable stress response mechanism with good acclimatization and bioremediation properties. This review aims to provide new insights on the importance of Chlorella in the treatment of industrial effluents. It provides a comprehensive summary of investigations that have proved the potential of Chlorella vulgaris, Chlorella minutissima, Chlorella sorokiniana, Chlorella kessleri, Chlorella ellipsoidea, Chlorella emersonii, Chlorella pyrenoidosa in the elimination of contaminants. Furthermore, highlights the mechanisms that Chlorella undergo in the effluent medium towards the removal of various contaminants.

Comprehensive review of industrial wastewater treatment techniques

Water is an indispensable resource for human activity and the environment. Industrial activities generate vast quantities of wastewater that may be heavily polluted or contain toxic contaminants, posing environmental and public health challenges. Different industries generate wastewater with widely varying characteristics, such as the quantity generated, concentration, and pollutant type. It is essential to understand these characteristics to select available treatment techniques for implementation in wastewater treatment facilities to promote sustainable water usage. This review article provides an overview of wastewaters generated by various industries and commonly applied treatment techniques. The characteristics, advantages, and disadvantages of physical, chemical, and biological treatment methods are presented.

Advancing sustainability in the steel industry: the key role of the triple helix sectors

The steel industry, crucial to the global economy, grapples with critical sustainable challenges, including high energy consumption, greenhouse gas emissions, and non-renewable resource utilization, making sustainability imperative for upholding its economic role without compromising the planet or societal well-being. This study proposes a framework aimed at advancing sustainability in the steel industry through the articulation of the triple helix sectors (university, industry, and government). Based on the integrative review scientific method, systematic selection, interpretation, and synthesis of information from various sources were carried out to map a technical-scientific scenario of sustainability in the steel industry. This scenario informed benchmarking which, in light of the scientific theory and the authors' expertise, enabled the proposition of customized actions aimed at the triple helix actors. The main theoretical-scientific contribution lies in deepening and expanding the knowledge that connects sustainability to the steel industry, thus reinforcing the basis for future research and empirical studies. As for the managerial-applied contribution, this work can guide universities in developing sustainable projects and establishing industrial partnerships; steel companies benefit from the best practices and technologies, while also achieving regulatory compliance; and governments can promote public policies that boost sustainability in the steel sector.

Biological wastewater treatment: a comprehensive sustainability analysis using life cycle assessment

The research conducts a life cycle assessment (LCA) on wastewater treatment (WWT) methods-membrane bioreactor (MBR), soil biotechnology (SBT), and bio-electrochemical constructed wetlands (BCW)-in comparison with the conventional activated sludge process (ASP). Employing SimaPro v9.5 with a cradle-to-gate system boundary, the analysis utilizes the IMPACT 2002 + method, employing per cubic meter of treated wastewater as the functional unit. The analysis shows that SBT exhibits the lowest environmental impacts among the considered WWT methods. The global warming potential was 0.0996 kg CO2 eq. for SBT, 1.33 kg CO2 eq. for MBR, 0.131 kg CO2 eq. for BCW, and 0.544 kg CO2 eq. for ASP. BCW demonstrates a 75.91% decrease, while MBR exhibits a 144.48% increase compared to ASP. Notably, electricity consumption emerges as the primary contributor to environmental impact in MBR and ASP. The resource impact category varies with a 138.15% increase in MBR and an 83.41% decrease in SBT compared to ASP. Additionally, the research indicates that the high human health impact observed in MBR results mainly from increased carcinogens (0.00176 kg C2H3Cl eq.), non-carcinogens (0.01 kg C2H3Cl eq.), and ionizing radiation (3.34 Bq C-14 eq.). The findings underscore the importance of considering treatment efficiency and broader environmental implications in selecting WWT methods. As the world emphasizes sustainability, such LCA studies provide valuable insights for making informed decisions in wastewater management.

Green industry work: production of FeCl3 from iron and steel industry waste (mill scale) and its use in wastewater treatment

Mill scale (MS) is considered to be a significant metallurgical waste, but there is no economical method yet to utilize its metal content. In this study, which covers various processes in several stages, the solution of iron in MS, which is the Iron and Steel Industry (I&SI) waste, as FeCl3 (MS-FeCl3) in the thermoreactor in the presence of HCl, was investigated. In the next step, the conditions for using this solution as a coagulant in the treatment of I&SI wastewater were investigated using the jar test. The results of the treated water sample were compared by chemical oxygen demand (COD), total suspended solids (TSS), color, and turbidity analyses using commercial aluminum sulfate (Al2(SO4)3) and FeCl3 (C-FeCl3). Additionally, heavy metal analyses were conducted, and the treatment performance of three coagulants was presented. Accordingly, while 2.0 mg/L anionic polyelectrolyte was consumed at a dosage of 4.05 mg/L Al2(SO4)3 at pH 7.0, 0.25 mg/L anionic polyelectrolyte was consumed at a dosage of 1.29 mg/L at pH 5.0 in the C-FeCl3 and MS-FeCl3 studies. Also, Fe, Cr, Mn, Ni, Zn, Cd, Hg, and Pb removal efficiencies were over 93.56% for all three coagulant usage cases. The results showed that the wastewater treatment performance of MS-FeCl3 by the recycling of MS, which is an I&SI waste, was at the same level as C-FeCl3. Thus, thanks to recycling, waste scale can be used as an alternative to commercial products for green production.

Hydrogeochemical characterisation and geospatial analysis of groundwater for drinking water quality in Ludhiana district of Punjab, India

This study characterises the quality of groundwater for the Ludhiana district of Punjab, India by analysing water samples collected from 152 locations spread across 3767 km². The samples were analysed for 18 parameters consisting of pH, EC, TDS, TA, TH, major anions and cations. The parameter values have been used to calculate the drinking water quality index of the study area which suggests that 2.6, 57.9, 32.9, 4 and 2.6% of the samples fall under the excellent, good, poor, very poor and unsuitable categories, respectively. The sequence of abundance for ions (in meq/l) as revealed from the laboratory tests is Na⁺ (37.1%) > Ca²⁺ (30.8%) > Mg²⁺ (29.1%) > K⁺ (2.8%) for cations and HCO₃^- (80%) > Cl^¯ (8.9%) > CO₃^2- (6.5%) > SO₄^2- (3.9%) > NO₃^-, F^-, PO₄^3- (< 1%) for anions. The spatial variability of these parameters has been depicted through the use of interpolation maps. Evaluation of different ionic ratios indicates that carbonate weathering and silicate weathering are both significantly affecting the groundwater chemistry with a slight dominance of carbonate weathering. Also, the ion exchange process is taking place in the area as confirmed by CAI index values. In terms of saturation index, the groundwater is undersaturated with respect to halite, fluorite and sylvite, whereas it is supersaturated for calcite, dolomite and aragonite minerals. The principal components in PCA explained 75.4% of the total variance with 29.1 and 28.3% contributions from PC1 and PC2. Both of these components indicate towards the geogenic and anthropogenic influence on groundwater mineralization of the area. The analysis suggests that groundwater for the study area is suitable for drinking in most of the region expect in a few places. Such a study could be used to understand the current status of groundwater quality in the area, the results of which can be used to prevent further contamination and sustain the resource for the future.