Environmental pollution associated with the discharge of textile industries is becoming a global concern. There is an imperative need for developing efficient, environmentally friendly, and cost-effective techniques for treating the wastewater containing dyes. Bioremediation of dyes is a fascinating approach to treat the textile effluents as it offers many advantages over the conventional treatment techniques. This review critically evaluates the latest advancements in applications of bioremediation techniques for the removal of various dyes from wastewater. The applications of various microorganisms such as bacteria, algae, fungi, yeast, and enzymes for the uptake of dyes are portrayed in detail. The current advancements in the bioremediation of textile effluents, research opportunities, challenges, and future outlook are emphasized. It also highlights the progress in bioremediation of dyes using bioreactors and microbial fuel cells. This review is beneficial in understanding the current status of bioremediation in water purification and accelerating the research focusing the role of bioremediation in water purification applications in future.

Bioremediation of dyes: Current status and prospects

In the last 3 years alone, over 10,000 publications have appeared on the topic of dye removal, including over 300 reviews. Thus, the topic is very relevant, although there are few articles on the practical applications on an industrial scale of the results obtained in research laboratories. Therefore, in this review, we focus on advanced oxidation methods integrated with biological methods, widely recognized as highly efficient treatments for recalcitrant wastewater, that have the best chance of industrial application. It is extremely important to know all the phenomena and mechanisms that occur during the process of removing dyestuffs and the products of their degradation from wastewater to prevent their penetration into drinking water sources. Therefore, particular attention is paid to understanding the mechanisms of both chemical and biological degradation of dyes, and the kinetics of these processes, which are important from a design point of view, as well as the performance and implementation of these operations on a larger scale.

https://www.mdpi.com/1420-3049/26/4/870/pdf

Recent Achievements in Dyes Removal Focused on Advanced Oxidation Processes Integrated with Biological Methods

The study aims to examine the CO2 emissions by considering the implication of COVID-19 under strict lockdown in India. The nonlinear (asymmetric) relationship is investigated between CO2 emission and COVID-19 with its specific determinants. The positive and negative asymmetries of COVID-19 determinants are also captured by using econometric techniques. The daily data series of CO2 emission, new confirmed cases, confirmed deaths, and lockdown as dummy variables from January 30, 2020, to December 1, 2020, for India is analyzed by employing the nonlinear autoregressive distributed lag model. This research revealed a significant nonlinear relationship between CO2 emission and COVID-19. The bound test and asymmetric coefficients are confirmed by the variables' long- and short-run relationships. The dynamic multiplier graphs present that India's strict lockdown due to the rapid increase in COVID-19 patients significantly reduces toxic gas emissions, especially CO2 emissions. This asymmetric relationship has been proficiently declared that unhealthy public routine, extra traffic, and unhygienic gases released in the air become the reason for environmental destruction. The lockdown is practically imposed for specific periods and reasons, contributing to reducing toxic emissions, but it is not a permanent solution for environmental sustainability. The government of India, policymakers, and environmentalists should make people aware of unhealthy and environmentally envying activities and policies and long-term applicable strategies should be designed to upgrade the environment's quality.

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Modeling the relationship between carbon emissions and environmental sustainability during COVID-19: a new evidence from asymmetric ARDL cointegration approach.

Engineered biochar: A multifunctional material for energy and environment.

This study aimed to evaluate the use of Moringa oleifera (MO) seed aqueous extract for tertiary treatment of a domestic wastewater by coagulation, flocculation, sedimentation, and rapid granular filtration. Jar tests with sand filter coupled were performed in secondary effluent samples with MO and alum dosages to evaluate the capacity to remove apparent color, turbidity, BOD, COD, TOC, nutrients, generated sludge, pH, and alkalinity consumption. Effects on the bacterial load (total coliforms and Escherichia coli), antibacterial activity in vitro (Escherichia coli Strain ATCC 25922), and cytotoxicity (Vero cells) were also evaluated. MO at the optimal dosage of 600 mg/L showed results statistically equal to the use of alum (200 mg/L), achieving bacterial load, turbidity, and apparent color removal higher than 99 %, 92 %, and 66 %, respectively. Differently from alum, the MO dosage increase did not consume alkalinity or change pH value. MO produced a more organic sludge, with total solids 1.8 times lower, and 3 times less bulky sludge than alum. Treatment with MO did not remove nutrients and increased organic matter (BOD, COD, and TOC). However, treatment with MO resulted in an effluent with less cytotoxicity, when compared with alum. MO did not show significant antibacterial activity, which may be related to the applied dosages. These results emphasized that MO seed aqueous extract has the potential to be used as a coagulant for domestic wastewater tertiary treatment, but a purification process of extracting cationic proteins from MO seeds is recommended when the effluent organic load is a concern.

Use of Moringa oleifera seed as a natural coagulant in domestic wastewater tertiary treatment: Physicochemical, cytotoxicity and bacterial load evaluation

A state-of-the-art review on WWTP associated bioaerosols: Microbial diversity, potential emission stages, dispersion factors, and control strategies.

Greenhouse gases emission control in WWTS via potential operational strategies: A critical review.

This study aimed at evaluating the Moringa oleifera (M. oleifera) seed powder for treatment of segregated (dye rich, DR; and starch rich, SR) and mixed wastewater (AM) streams of a textile industry. Two different sizes (

Parametric and kinetic investigations on segregated and mixed textile effluent streams using Moringa oleifera seed powders of different sizes

Investigations on air quality of a critically polluted industrial city using multivariate statistical methods: Way forward for future sustainability.

India is a veritable emporium of numerous restorative and fragrant plants. A notable plant for its characteristics is Moringa oleifera. M. oleifera is used in many different forms, i.e. seed powder after removing husks and M. oleifera cake powder with/without husk extract. The moringa plant mostly bears fruit after the second year but its pods can start within 6–8 months after planting. The moringa tree fruits for several years. The moringa tree does not tolerate frost or freezing. M. oleifera with different forms can be used for treatment of water and wastewater. The seeds of the M. oleifera tree contain water-soluble, positively charged proteins that will act as an effective coagulant for water/wastewater treatment. Heavy metals are one of the most important factors to be considered while treating wastewater. The important and best finding of using M. oleifera as a coagulant for wastewater treatment is the reduction of turbidity.

Hirendrasinh Padhiyar

Papers

A state-of-the-art review on WWTP associated bioaerosols: Microbial diversity, potential emission stages, dispersion factors, and control strategies.

Greenhouse gases emission control in WWTS via potential operational strategies: A critical review.

Parametric and kinetic investigations on segregated and mixed textile effluent streams using Moringa oleifera seed powders of different sizes

Investigations on air quality of a critically polluted industrial city using multivariate statistical methods: Way forward for future sustainability.

Applications of Moringa Oleifera for Wastewater Treatment : Concepts and Approaches