Leather has been a commodity since ancient times, when primitive men hunted animals for food and used their hides and skins for clothes and tents. Nowadays, the tanning process is highly industrialised. The chromium tanning is the most widely used because it produces high-quality leather despite its serious environmental impacts. The purpose of this study is to analyse the environmental impact of an Indian company that carries out post-tanning operations on bovine hides, that is to say, from the so-called wet-blue to finished crust. To do this, the Life Cycle Assessment (LCA) is implemented using the primary data provided by the company. The analysis has been carried out by the OpenLCA software, and 16 environmental impact categories have been evaluated. The results show that the processes for producing fuel (coal and diesel oil) and chromium(III) salts are the main contributors to the environmental impact for nearly all categories. These types of impacts are upstream, whereas the operations carried out by the company have impacts on the climate change category, due to the use of fossil fuels in the production process. Therefore, the direct action that the company could take is the substitution of fuel to produce energy with a renewable energy source. The comparison of these results with the whole tanning process present in the software confirms the limited impact of the post-tanning. At last, the results also evidence the methodological value of Life Cycle Assessment, which can be used to show what can be improved in one installation to reduce its environmental impact.

N,N-Diethyl-m-toluamide (DEET) is one of the significant chemical formulations used extensively in personal care products as a preventive measure against mosquito-borne diseases. It has been detected in the aquatic matrix at various concentrations from ng/L to mg/L. Chlorella vulgaris is one of the potential algal species for the treatment of wastewater containing personal care products, and this study investigates the acute toxicity and removal potential of Chlorella vulgaris in the removal of DEET with its effects on pigments and biochemical composition. The 96-h EC50 was calculated to be 17.4 mg/L, and the biochemical composition assessment revealed that lipid concentrations in Chlorella vulgaris increased until the tolerance limit. This investigation revealed that when DEET concentration crossed the tolerance limit (17.4 mg/L) in the medium, the pigments and biochemical concentrations reduced drastically, indicating Chlorella vulgaris inhibitory response beyond the tolerance limit, causing irreversible damage to the algal cells. Furthermore, Chlorella vulgaris removal potential at three different test runs, T1 (5 mg/L), T2 (10 mg/L), and T3 (25 mg/L) were studied. The most remarkable elimination in T1 test runs was 72% due to biodegradation, followed by T2 (35%) and T3 (15%). T1 conditions resulted in more significant lipid formation than other test runs, making biofuel for DEET-contaminated wastewater a feasible alternative.

Coffee processing wastewater (CPWW) treatment through conventional techniques is less efficient due to the inherent characteristics of CPWW, low reaction kinetics, and the presence of toxic and/or recalcitrant compounds. Therefore, advanced oxidation processes (AOPs) emerge as a promising avenue for their treatment. These AOPs leverage highly reactive oxidants, such as hydroxyl radicals (center dot OH), to effectively degrade and mineralize a wide spectrum of pollutants present in CPWW. The AOP approaches include ozone-based, electrical energy-based, Fenton-based, and plasma-based processes, and their combinations have often resulted in higher pollutant removal efficiency. In this context, the pollutant removal mechanisms of the aforementioned processes have been critically discussed. Besides, the current developments and future directions for the treatment of CPWW have also been delineated. The treatment of CPWW through the AOP approach might cater to attaining the United Nations Sustainable Development Goals, aimed at creating a healthy planet with accessibility to clean water.

Solar Fenton is an important and extensively used advanced oxidation process (AOP) to degrade pharmaceutical pollutants. The objective of this study was to evaluate the performance of simultaneous degradation of the mixed pollutants (amoxicillin, acetaminophen, and ciprofloxacin) for an aqueous solution using the solar Fenton process. Operating parameters such as pH, iron doses, H2O2 doses, pollutant concentrations, and time were studied. From the experimental results, the ideal conditions were obtained for the removal of mixed pollutants such as pH 3, Fe2+ 0.04 mM, H2O2 4 mM, the concentration of the mixed pollutants 5 mg/L, solar radiation 400 W/m2, and time 10 min, respectively. The pseudo-first-order kinetics were utilized to investigate the degradation efficacy of the mixed pollutants. The result of the study indicates that the degradation efficiency was > 99

Ciprofloxacin (CIP) and norfloxacin (NOR) belong to the organic contaminants of emerging concern (OCECs) that are frequently detected in wastewater matrices at ng/L to mg/L concentrations. This study investigates the potential of Scenedesmus obliquus in the treatment of CIP and NOR as a binary mixture from raw wastewater. Optimization of inoculum was done to find the required cell density concentration that has less inhibition and high removal. The optimum inoculum (cell density: 200 × 105 cells/mL and OD680: 1.0) has shown 75% removal with no inhibition of growth. A pilot scale study was conducted in controlled environment using high-rate algal pond to investigate the contribution of abiotic and biotic removal. Abiotic removal is negligible in comparison with the biotic contribution of removal. The order of removal efficiency is observed as COD (88%) > NOR (84.8%) > CIP (84.6%) > NH4+ (71.7%) with biodegradation as the major removal mechanism. Biotransformed products of CIP + NOR were identified inside the Scenedesmus obliquus. During the pilot-scale study, Biomass (3.70 ± 0.07 g/L) was harvested with carbohydrates (17.85 ± 0.1%), lipids (38.36 ± 0.13%), and proteins (28.18 ± 1.63%). Lipid productivity in binary mixture was 2.6 times higher than the lipid production in control condition. Transesterification of these lipids yielded good biofuel composition of 32.72% of saturated fatty acids and 21.7% of unsaturated fatty acids.

The tannery is an old industrial sector well-developed, plays an important role in the global economy, and has been heavily industrialized over the years in all countries. In developed countries, the legislation forces the tannery sector to develop clean and sustainable production. Due to the strict legislation policies, there was a continuous change in the distribution of the processing sites. There are two main reasons for this shift of the distribution, namely: 1) lower labour costs in some countries than in others; 2) fewer environmental restrictions in some countries than in others.

The widespread pharmaceutical pollutants enter the aquatic environment through wastewater, and it poses a threat to aquatic organisms and human health. Advanced oxidation process (AOPs) is one of the widely used treatment methods for the degradation of pharmaceutical pollutants by utilizing Ultraviolet light (UV), iron (Fe2+), and hydrogen peroxide (H2O2). This study investigates the application of AOP (UV/Fe2+/H2O2) for the degradation kinetics of mixed pollutants (amoxicillin, acetaminophen, and ciprofloxacin), mineralization, and degradation products. The sources for these pollutants are hospitals, households, manufacturing industries, etc. The effects of degradation were evaluated by varying pH, Fe2+, H2O2, the mixed pollutants, and time respec-tively. The results revealed that the optimal conditions were observed at UV light 15 W, mixed pollutant 5 mg/L, Fe2+ 0.04 mM, H2O2 3 mM, and time 10 min. The maximum degradation was achieved at >99 % in the mixed pollutants with the kinetics in the order of ACET > CIP > AMX. The maximum mineralization was observed at 68 % and transformation products were identified using LC-ESI-MS. In addition, the process performance of the UV/Fe2+/H2O2 method was assessed by applying optimum conditions in real wastewater (raw sewage and hospital wastewater). The study revealed that the UV/Fe2+/H2O2 method had a high performance in the removal of multiple pollutants in real wastewater.

This study investigates the acute toxicity and removal capacity of the native isolated species Stichococcus bacillaris towards Ciprofloxacin (CIP) and compared its efficiency with the most explored algal species Chlorella pyrenoidosa and Scenedesmus obliquus in antibiotic removal. The toxicity assessment revealed that 24 hr EC50 values are in the order of Stichococcus bacillaris (64 mg/L) > Chlorella pyrenoidosa (52 mg/L) > Scenedesmus obliquus (42 mg/L) and 24 hr LC50 values are in the order of Stichococcus bacillaris (313 mg/L) > Chlorella pyrenoidosa (228 mg/L) > Scenedesmus obliquus (197 mg/L). Furthermore, CIP (5 mg/L) was spiked into the algal medium to study their removal potential for 7 days. Stichococcus bacillaris and Scenedesmus obliquus reported higher removal efficiency (40%) compared to Chlorella pyrenoidosa (28%) with biodegradation as the major contributing removal mechanism in all the species with the order of Stichococcus bacillaris (84%) > Scenedesmus obliquus (80%) > Chlorella pyrenoidosa (59%). Biochemical characterization revealed that Scenedesmus obliquus is a suitable candidate for biodiesel production as the lipid production (830 mg/L) is higher in this species and Stichococcus bacillaris is suitable for bioethanol production as the carbohydrates production (609 mg/L) is substantial in this species.

Marine environment is a predominant player in the overall ecosystem functioning with almost half of oxygen evolution into the atmosphere through the photosynthetic activity of plankton communities. Anthropogenic activities cause pollution at an enhanced pace and pose a major threat to the biological cyclings in the marine ecosystem. Pollutants such as heavy metals and organic compounds in the marine environment are a serious concern as they are associated with complex challenges. Marine microalgae are promising candidates in remediating inorganic and organic pollutants due to their versatile metabolic mechanisms. The present chapter provides a comprehensive understanding of the response of marine microalgae in the removal of heavy metals and organic pollutants. Initially, we present the importance of microalgae and the sources of heavy metals and organic pollutants that reach the marine environment besides highlighting the merits and demerits of the conventional and biological treatment systems used for the removal of these pollutants. Finally, we provide a general perspective on the implication of marine microalgae and the associated mechanisms in the removal of heavy metals and organic pollutants.

Soil pollution with emerging contaminants such as human and veterinary pharmaceuticals, antibiotics, steroids, endocrine disruptors, perfluorinated compounds, water disinfection by-products, gasoline, industrial additives, and microplastics is one of the most persistent environmental problems, which poses a serious threat to the humans and the environment. Phytoremediation, one of the innovative strategies for remediating the soil polluted by such emerging contaminants, has been recognized as a powerful in situ approach to soil remediation. The synergistic actions of plants and their associated microorganisms can improve plant growth and enhance the biodegradation of emerging contaminants, thereby accelerating the removal of these pollutants from the soil. In view of the aforementioned discussion, this book chapter is designed to cover the plant species demonstrating higher removal efficiency of emerging contaminants from soil, explain different factors influencing phytoremediation of emerging contaminants in soil, and discuss the different fundamental mechanisms of endophyte-assisted phytoremediation of emerging contaminants. Finally, the advances, challenges, and new directions in the field of phytoremediation technology for the removal of selected emerging contaminants are also discussed.

Ciprofloxacin (CIP) and norfloxacin (NOR) belong to the class of emerging contaminants that are frequently detected in the aquatic environment as a binary mixture, responsible for the development of antibiotic-resistant genes and antibiotic-resistant bacteria. This study aims to investigate five different algal species Chlorella vulgaris ( Cv ), Chlorella pyrenoidosa ( Cp ), Scenedesmus obliquus ( So ), Tetradesmus sp ( T ) and Monoraphidium sp ( M ) for their tolerance and removal of binary mixture. The effects on biochemical composition in the algal species concerning the binary mixture and its removal efficiency are first reported in this study. The acute toxicity (96 h EC 50 ) values are in the order of So > Cp > T > M > Cv , Chlorella vulgaris is the most sensitive algal species with 17.73 ± 0.24 mg/L and Scenedesmus obliquus is the least sensitive algal species with 39.19 ± 0.79 mg/L. The removal efficiency of the binary mixture was found to be in the order of So > Cp > T > M > Cv , Scenedesmus obliquus removed CIP (52.4%) and NOR (87.5%) with biodegradation as the major contributing removal mechanism. Furthermore, less toxic biotransformed products were detected in Scenedesmus obliquus and the biochemical characterization revealed that the growth-stimulating effect is higher with lipid (35%), carbohydrate (18%), and protein (33%) providing an advantage in the production of valuable biomass.

In the recent times, more attention is on industrial waste management due to the unaffordable space for dump yards and landfills and the increased charges for waste dumping. Even though the vegan revolution and plantbased meat products are booming, the traditional slaughterhouses and the wastes produced by them continue to be a concern. Waste valorisation is an established procedure striving to create a closed chain process in industries where there is no refuse. Although a highly polluting industry, slaughterhouse industry wastes have been recycled to economically viable leather since ancient times. However, the tannery industry is causing pollution in par with or even more than the slaughterhouses. Effective management of the liquid and solid wastes from the tannery is of utmost concern because of its toxicity. The hazardous wastes generated enter the food chain, causing long term impacts in the ecosystem. Several leather waste transformation processes are widely used in the industries, and they are yielding good products of economic value. However careful exploration into the processes and products of waste valorisation are often ignored as long as the transformed waste product is of higher value than the waste. The most efficient and environmentally friendly waste management technique should convert the refuse into a value-added utilization without any toxic leftovers. Zero waste concept is an extension of the zero liquid discharge concept, where the solid waste is also treated and reused to such an extent that there is no residue to be sent to the landfill. This review initially presents the existing methods for the detoxification of tannery wastes and examines the possibility of solid waste management within the tannery industry to attain zero waste discharge.

Acid soils are the degraded (nutrient-poor) soils that generally lack microbial abundance required to promote plant growth. An insight into the microbial diversity in highly acidic soils is crucial from both ecological and environmental standpoints. Previously, we showed that inoculation of acid soils with acid-tolerant microalgae (algalization) significantly improved soil physicochemical and biological characteristics. In the present novel study involving a laboratory microcosm, high-throughput 16S rRNA amplicon sequencing analysis was performed to investigate the bacterial diversity in acid soils algalized with Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 after 90 days of incubation. Our results on pooled DNA demonstrate that algalization of two acid soils (soil A and B) significantly increased several bacterial genera, and this observation is consistent with Shannon and Chao1 diversity indices. Actinobacteria, Acidobacteria, Firmicutes, and Proteobacteria were the most prevalent phyla enriched in all of the algalized treatments. Interestingly, nonalgalized acid soils favored only Firmicutes and Actinobacteria, but algalization significantly enriched Proteobacteria, Acidobacteria, and Actinobacteria. Canonical correspondence analysis revealed a positive effect of pH in soil A and both pH and organic carbon in soil B on enrichment. Furthermore, soil bacteria of ecological significance that belong to rhizobacteria and diazotrophs, such as Acetobacter, Azospirillum, Bradyrhizobium, Gluconacetobacter, Nitrobacter, Burkholderia, Comamonas, Herbaspirillum, Enterobacter, Nitrosococcus, Brevibacillus, Enterococcus, Frankia, and Anabaena, were greatly enriched in algalized treatments. Thus, we demonstrate here for the first time that algalization of acid soils significantly improves soil health through enrichment of bacteria that are largely implicated in promoting soil health and plant growth.

Antibiotics are frequently detected in the aquatic environment due to their excessive usage and low-efficiency removal in wastewater treatment plants. This can provide the origin to the development of antibiotic-resistant genes in the microbial community, with considerable ecotoxicity to the environment. Among the antibiotics, the occurrence of ciprofloxacin (CIP) and amoxicillin (AMX) has been detected in various water matrices at different concentrations around the Earth. They are designated as emerging contaminants (ECs). Microalga Chlorella vulgaris (C. vulgaris) has been extensively employed in phycoremediation studies for its acclimatization property, non-target organisms for antibiotics, and the production of value-added bioproducts utilizing the nutrients from the wastewater. In this study, C. vulgaris medium was spiked with 5 mg/L of CIP and AMX, and investigated for its growth-stimulating effects, antibiotic removal capabilities, and its effects on the biochemical composition of algal cells compared to the control medium for 7 days. The results demonstrated that C. vulgaris adapted the antibiotic spiked medium and removed CIP (37 ± 2%) and AMX (25 ± 3%), respectively. The operating mechanisms were bioadsorption, followed by bioaccumulation, and biodegradation, with an increase in cell density up to 46 ± 3% (CIP) and 36 ± 4% (AMX), compared to the control medium. Further investigations revealed that, in the CIP stress-induced algal medium, an increase in major photosynthetic pigment chlorophyll-a (30%) and biochemical composition (lipids (50%), carbohydrates (32%), and proteins (65%)) was observed, respectively, compared to the control medium. In the AMX stress-induced algal medium, increases in chlorophyll-a (22%), lipids (46%), carbohydrates (45%), and proteins (49%) production were observed compared to the control medium. Comparing the two different stress conditions and considering that CIP is more toxic than AMX, this study provided insights on the photosynthetic activity and biochemical composition of C. vulgaris during the stress conditions and the response of algae towards the specific antibiotic stress. The current study confirmed the ability of C. vulgaris to adapt, bioadsorb, bioaccumulate, and biodegrade emerging contaminants. Moreover, the results showed that C. vulgaris is not only able to remove CIP and AMX from the medium but also can increase the production of valuable biomass usable in the production of various bioproducts.

The goal of this research is to produce bio-alcohol and biodiesel from S. quadricauda and C. pyrenoidosa microalgae in a sustainable manner using phototrophic and heterotrophic pathways. Experimental and statistical approaches are used to assess the viability of the bioenergy produced as a prospective alternative to diesel fuel. On analysis, it was observed that the %age weight of the dry cell of C. pyrenoidosa cultures on scaling-up resulted lipid content of 44.1%, 46.7%, and 41%, respectively. On scaling up, the cultures' biomass concentrations reached 5.15 g L-1, 4.24 g L-1, and 4.36 g L-1. Similarly, upscaling S. quadricauda cultures resulted in yield rates of 4.2 g L-1 and 2.96 g L-1 d-1 and a lipid productivity of 2.96 g L-1 d(-1), respectively. On engine testing, AA20D80 and AA30D70 blend combinations shows an improvement of 4.84% and 6.9% in BTE with a reduction of 88.6% and 72.41% in fuel consumption. Similarly, as compared to amyl alcohol blends and diesel fuel at full load, CP20D80 and CP30D70 efficiently lower HC, NOx, and smoke emissions. The statistical analysis revealed that the similarity index of the 20% and 30% proportions were ideal in achieving optimal engine output characteristics.

Municipal solid waste (MSW) leachate is a highly polluted liquid that accumulates in the landfill and contains a high concentration of toxic pollutants which can pollute the surrounding surface water and groundwater as well, if not treated properly. In this study, an integrated approach of phycoremediation with photolytic ozonation was employed for the leachate collected from the MSW dumpsite which has high Chemical Oxygen Demand (COD) and ammonium (NH4+) levels. Photolytic ozonation treatment was employed as a pre-treatment step under operating parameters of pH: 9.0; Ozone dosage: 5 g/h; UV-C: λ = 254 nm; and contact time: 60 min, in which the COD and NH4+ in the leachate was reduced up to 81% and 95%, respectively. The selected algae Chlorella vulgaris (C.vulgaris) was employed in a lab-scale study to optimize the inoculum conditions in the photolytic ozonated leachate (POL). The specific growth rate of C.vulgaris was observed as 0.14/d in the POL at the optimized condition (inoculum size of 25% (T25)) during the study period of 11 days. High-rate algal pond (HRAP) was employed for the pilot-scale study in controlled environmental conditions as in the T25 experimental run for the assessment of POL treatment and biomass production. C.vulgaris reduced the concentration of pollutants COD, NH4+, and heavy metals (Cu, Fe) in the POL up to 93%, 94%, and 71%, respectively, with the dry biomass productivity of 0.727 g/L/d which is 3 times higher than the biomass productivity of C.vulgaris in freshwater conditions. The biochemical composition (carbohydrates, proteins, and lipids) of the harvested biomass has higher lipid production with lipid productivity of 120 mg/L/d which can be used as a feedstock for the production of value-a dded products.

Pharmaceuticals and personal care products (PPCPs) are of emerging concerns because of their large usage, persistent nature which promised their continuous disposal into the environment, as these pollutants are stable enough to pass through wastewater treatment plants causing hazardous effects on all the organisms through bioaccumulation, biomagnification, and bioconcentration. The available technologies are not capable of eliminating all the PPCPs along with their degraded products but phycoremediation has the advantage over these technologies by biodegrading the pollutants without developing resistant genes. Even though phycoremediation has many advantages, industries have found difficulty in adapting this technology as a single-stage treatment process. To overcome these drawbacks recent research studies have focused on developing technology that integrated phycoremediation with the commonly employed treatment processes that are in operation for treating the PPCPs effectively. This review paper focuses on such research approaches that focused on integrating phycoremediation with other technologies such as activated sludge process (ASP), advanced oxidation process (AOP), Up-flow anaerobic sludge blanket reactor (UASBR), UV irradiation, and constructed wetland (CW) with the advantages and limitations of each integration processes. Furthermore, augmenting phycoremediation by co-metabolic mechanism with the addition of sodium chloride, sodium acetate, and glucose for the removal of PPCPs has been highlighted in this review paper.

The heterogeneous catalyst plays an important role in the production of biodiesel at industrial level. In present work, the utilization of wollastonite as a heterogeneous catalyst is attempted to explore its non-biomedical application. Wollastonite was synthesized by using the auto combustion method and L-alanine was used as a fuel for combustion. The X-ray diffraction pattern reveals the phase purity of wollastonite. The Fourier transform infrared spectra of the calcined precursor show the presence of characteristics functional groups in wollastonite. To evaluate the catalytic ability of the prepared wollastonite, transesterification reaction of soybean oil with methanol was performed. Following the reaction, the biodiesel, glycerol and the catalyst were separated by centrifugation. Optimization of the percentage of catalyst used in biodiesel production was done by using various quantities of catalyst during the transesterification reaction and subjecting the produced biodiesel to gas chromatography. It can be concluded that combined alkali metal oxide and silica in wollastonite has assisted in production of biodiesel (82.6%) in a less time and at a low temperature.

The tannery industry is characterized by the consumption of a large quantity of water, around 30–40 m3 for processing 1000 kg of hide or skin. This amount becomes wastewater, containing about 300 kg of different chemicals, mainly refractory organic compounds, with high chemical oxygen demand (COD), total dissolved salts (TDS), chromium, and evolution of toxic gases, such as ammonia and sulfides, etc. The remaining tanning chemicals are released as effluent having high resistance against biological degradation, becoming a serious environmental issue. Usually, end-of-pipe treatment is not sufficient to meet the concerns of environmental issues. In terms of cleaner production options, the redesigning of the existing effluent treatment procedures with alternate or additional treatment techniques, which “supports resource recovery with no added chemicals”, is expected to give a sustainable solution for the management of toxic effluent. The Zero Liquid Discharge (ZLD) system serves to ensure zero water emission, as well as treatment facilities by recycling, recovery, and reuse of the treated wastewater using advanced cleanup technology. The international scenario shows the implementation of ZLD thanks to pressure from regulatory agencies. The ZLD system consists of a pre-treatment system with conventional physicochemical treatment, tertiary treatment, softening of the treated effluent, reverse osmosis (RO) treatment for desalination, and thermal evaporation of the saline reject from RO to separate the salts. By adopting this system, water consumption is reduced. Moreover, ZLD also becomes effective in disaster mitigation in areas where the tannery industry is a strong economic actor. With this review, we aim to give an outlook of the current framework.