Bioremediation Of Wastewater Research Articles

The Bioremediation of Industrial Effluents by Phanerochaete chrysosporium: The COD, TOC Removal Efficiency and Biochemical Assessment for Dreissena polymorpha

AbstractBioremediation is one of the cheapest and easy method for biological treatment for most kind of industial wastewater. Bioremediation potential of the Phanerochaete chrysosporium for industrial wastewater from Industrial Zone Wastewater plant in Mardin, Turkey, was evaluated. The chemical oxygen demand (COD) and total organic carbon (TOC) reduction efficiencies of P. chrysoporium of on wastewater studied using biomarkers such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), Thiobarbituric Acid (TBARS) and reduced glutathione (GSH) levels in Dreissena polymorpha. The level of TBARS, a marker of lipid peroxidation was found to be high because of wastewater exposure after treatment. TBARS levels decreased (from 20.2 to 31.6 and from 20.8 to 37.5). GSH levels (from 52.3 to 15.9), CAT levels (from, 119.7 to 15.3 and from 91.1 to 13.4) SOD levels (from 3.8 to 0.9 and from 3.4 to 1.2) and GPX activity (from 177.2 to 104.4 and 174.2 to 100.5) decreased in the wastewater exposure groups during 24 and 96th hour compared to the control groups. GSH levels, CAT, SOD and GPX activity increased after treatment by P. chrysosporium. Results indicate that industrial wastewater caused oxidative stress in Dreissena polymorpha. The findings revealed that the highest removal efficiency for COD and TOC, at 86.3 % and 80.3 % respectively, occurred in the 1/20 diluted medium. P. chrysosporium has proven to be effective in the bioremediation of wastewater from the Industrial Zone Changes in biochemical parameters before and after bioremediation showed that antioxidant parameters such as CAT, SOD, GPx activities and GSH and TBARS levels can be used as biomarker to evaluate bioremediation efficiency.

Microalgal and activated sludge processing for biodegradation of textile dyes

The textile industry contributes substantially to water pollution. To investigate bioremediation of dye-containing wastewater, the decolorization and biotransformation of three textile azo dyes, Red HE8B, Reactive Green 27, and Acid Blue 29, were considered using an integrated remediation approach involving the microalga Chlamydomonas mexicana and activated sludge (ACS). At a 5 mg L−1 dye concentration, using C. mexicana and ACS alone, decolorization percentages of 39%–64% and 52%–54%, respectively, were obtained. In comparison, decolorization percentages of 75%–79% were obtained using a consortium of C. mexicana and ACS. The same trend was observed for the decolorization of dyes at higher concentrations, but the potential for decolorization was low. The toxic azo dyes adversely affect the growth of microalgae and at high concentration 50 mg L−1 the growth rate inhibited to 50–60% as compared to the control. The natural textile wastewater was also treated with the same pattern and got promising results of decolorization (90%). Moreover, the removal of BOD (82%), COD (72%), TN (64%), and TP (63%) was observed with the consortium. The HPLC and GC-MS confirm dye biotransformation, revealing the emergence of new peaks and the generation of multiple metabolites with more superficial structures, such as N-hydroxy-aniline, naphthalene-1-ol, and sodium hydroxy naphthalene. This analysis demonstrates the potential of the C. mexicana and ACS consortium for efficient, eco-friendly bioremediation of textile azo dyes.

Identification, degradation characteristics, and application of a newly isolated pyridine-degrading Paracidovorax sp. BN6-4.

The Paracidovorax sp. BN6-4 capable of degrading high concentrations of pyridine was isolated from the coking sludge. The removal rate of BN6-4 to 1,000 mg/L pyridine during 48 h was 97.49 ±1.59%. The primary intermediate metabolites of pyridine degradation by strain BN6-4 were identified by gas chromatography-mass spectrometry (GC-MS), including N-Ethylurea, acetamidoacetaldehyde, and N-Hydroxymethylacetamide, etc. Subsequently, two different biodegradation pathways of pyridine were proposed. First, the hydroxylation of pyridine to form the intermediates pyridin-2(1H)-one and 5,6-dihydropyridine-2,5-diol, the former undergoing oxidative ring opening and the latter oxidative ring opening via N-C2 and C2-C3 ring opening to ammonia and carbon dioxide. Furthermore, the organic matter was greatly degraded by the bioremediation of real coking wastewater using BN6-4. This study enriched the microbial resource for pyridine degradation and provided new insights about the biodegradation pathway of pyridine, which is of great significance for the pyridine pollution control and coking wastewater treatment.

Intensifying outdoor cultivation of oleaginous microalgae in photobioreactors for simultaneous wastewater bioremediation and low-cost production of renewable biodiesel feedstocks

Oleaginous microalgae are gaining increasing attention for simultaneous wastewater bioremediation and biofuel feedstock production. In this study, four oleaginous species of microalgae including Chlamydomonas sp. WWP, Scenedesmus sp. HP56, Haematococcus sp., and Nannochloropsis sp., were screened for their growth and lipid production at 30, 35, and 40 °C, under light intensity at 3, 4, and 5 klux. Among the strains screened, Haematococcus sp. grew best and gave comparable high growth at 30 °C and 35 °C (0.7–0.8 g/L) indicating its thermotolerant characteristic, and the optimal light intensity was found at 4 klux. Haematococcus sp. also grew well using unsterile secondary effluent from the seafood processing plant and produced high biomass (0.53–0.57 g/L) and lipids (0.17–0.19 g/L), especially in the column photobioreactor (CP). The repeated-batch outdoor cultivation mode showed that CP equipped with four-blade baffles was most efficient for the production of biomass (0.40–0.63 g/L) and lipids (0.15–0.30 g/L) during 4 cycles. The microalga also removed total nitrogen and total phosphorus from secondary effluent by 70.59% and 94.97%, respectively. The fatty acid compositions in microalgal lipids were C16-C18, especially palmitic acid, oleic acid, and linolenic acid, which show superior fuel properties, suggesting their promising use as biodiesel feedstocks. These strategies may have a significant impact not only on bioremediation of industrial effluent but also low-cost production of microalgae-based biodiesel feedstocks.

Bioremediation of tannery wastewater using UV-treated bacteria in the free and immobilized form

Bioremediation of tannery wastewater using UV-treated bacteria in the free and immobilized form

Biosand Reactors for Municipal and Industrial Wastewater Treatment: Status Quo, Challenges and Opportunities

Biosand reactors (BSRs), alternatively known as slow or biological sand filters, are passive systems that are used to remove contaminants from domestic wastewater, industrial wastewater and drinking water. This review focuses specifically on their application for remediation of industrial effluent and sewage-containing municipal and household effluent. The relationships between the physicochemical characteristics of the sand grains (size, size distribution, shape, chemical composition) and the hydraulic conductivity of the sand employed in BSFs are critically discussed in relationship to the achievable loading rates and hydraulic retention times. The modes of operation and influence of the functional microbial biomass as well as biodegradable and recalcitrant particulates on these parameters is comprehensively reviewed. Finally, the bioremediation of sewage-based and industrial wastewater is examined. This includes an account of the biotic and abiotic removal mechanisms and the limitations of BSRs for removal of pollutants such as phosphorus/phosphate and nitrates/nitrites. The removal mechanisms and removal efficiencies of macronutrients, micropollutants, fecal indicators and other microorganisms such as antibiotic-resistant bacteria in BSRs are discussed.

Evaluation of Antibiotic Biodegradation by a Versatile and Highly Active Recombinant Laccase from the Thermoalkaliphilic Bacterium Bacillus sp. FNT.

Laccases are industrially relevant enzymes that have gained great biotechnological importance. To date, most are of fungal and mesophilic origin; however, enzymes from extremophiles possess an even greater potential to withstand industrial conditions. In this study, we evaluate the potential of a recombinant spore-coat laccase from the thermoalkaliphilic bacterium Bacillus sp. FNT (FNTL) to biodegrade antibiotics from the tetracycline, β-lactams, and fluoroquinolone families. This extremozyme was previously characterized as being thermostable and highly active in a wide range of temperatures (20-90 °C) and very versatile towards several structurally different substrates, including recalcitrant environmental pollutants such as PAHs and synthetic dyes. First, molecular docking analyses were employed for initial ligand affinity screening in the modeled active site of FNTL. Then, the in silico findings were experimentally tested with four highly consumed antibiotics, representatives of each family: tetracycline, oxytetracycline, amoxicillin, and ciprofloxacin. HPLC results indicate that FNTL with help of the natural redox mediator acetosyringone, can efficiently biodegrade 91, 90, and 82% of tetracycline (0.5 mg mL-1) in 24 h at 40, 30, and 20 °C, respectively, with no apparent ecotoxicity of the products on E. coli and B. subtilis. These results complement our previous studies, highlighting the potential of this extremozyme for application in wastewater bioremediation.

Use of sawdust for production of ligninolytic enzymes by white-rot fungi and pharmaceutical removal.

Use of white-rot fungi for enzyme-based bioremediation of wastewater is of high interest. These fungi produce considerable amounts of extracellular ligninolytic enzymes during solid-state fermentation on lignocellulosic materials such as straw and sawdust. We used pure sawdust colonized by Pleurotus ostreatus, Trametes versicolor, and Ganoderma lucidum for extraction of ligninolytic enzymes in aqueous suspension. Crude enzyme suspensions of the three fungi, with laccase activity range 12-43 U/L and manganese peroxidase activity range 5-55 U/L, were evaluated for degradation of 11 selected pharmaceuticals spiked at environmentally relevant concentrations. Sulfamethoxazole was removed significantly in all treatments. The crude enzyme suspension from P. ostreatus achieved degradation of wider range of pharmaceuticals when the enzyme activity was increased. Brief homogenization of the colonized sawdust was also observed to be favorable, resulting in significant reductions after a short exposure of 5 min. The highest reduction was observed for sulfamethoxazole which was reduced by 84% compared to an autoclaved control without enzyme activity and for trimethoprim which was reduced by 60%. The compounds metoprolol, lidocaine, and venlafaxine were reduced by approximately 30% compared to the control. Overall, this study confirmed the potential of low-cost lignocellulosic material as a substrate for production of enzymes from white-rot fungi. However, monitoring over time in bioreactors revealed a rapid decrease in enzymatic ligninolytic activity.

Enrichment, domestication, degradation, adaptive mechanism, and nicosulfuron bioremediation of bacteria consortium YM21

Nicosulfuron (NSR), a sulfonylurea herbicide, can easily enter water bodies, affecting aquatic life and human safety. Here, bacteria consortium YM2 was enriched and domesticated from the active sludge of a pesticide plant for the bioremediation of NSR wastewater. The response surface methodology data revealed that under optimal incubation conditions: 9.41 g L–1 maltodextrin, 21.37 g L–1 yeast extract, and 12.45 g L–1 NaCl, YM2 bacteria consortium degraded 97.49% of NSR within 4 d. The optimal degradation conditions were temperature 30°C, pH 6.0, inoculum 1%, and initial NSR concentration 20 mg L–1), The degradation system was tolerant to heavy metal ions such as Cd2+, Pb2+, Ni2+, and Zn2+ and mainly occurred through the bacterial extracellular enzymes (92.17%). Mechanistically, during the degradation process, reactive oxygen species, oxidative stress, cell membrane permeability, cell surface hydrophobicity, and apoptosis rate first increased and then decreased. Also, the expression of biofilm formation-related genes luxS, waaE, spo0A, and wza varied with time and concentration. NSR wastewater and soil were degraded to 1.92 mg L–1 and 2.72 mg L–1, respectively. In a simulated wastewater treatment unit (hydraulic retention time 12 h), YM2 degraded 84.55% of NSR after 10 d. This study provides a theoretical basis for the microbial remediation of NSR.

Glycine betaine modulates extracellular polymeric substances to enhance microbial salinity tolerance

High salinity inhibits microbial activity in the bioremediation of saline wastewater. To alleviate osmotic stress, glycine betaine (GB), an osmoprotectant, is added to enhance the secretion of extracellular polymeric substances (EPS). These EPS are pivotal in withstanding environmental stressors, yet the intricate interplay between GB supplementation and microbial responses through EPS modifications—encompassing composition, molecular architecture, and electrochemical features—remains elusive in hypersaline conditions. Here we show microbial strategies for salinity endurance by investigating the impact of GB on the dynamic alterations of EPS properties. Our findings reveal that GB supplementation at 3.5% salinity elevates the total EPS (T-EPS) content from 12.50 ± 0.05 to 24.58 ± 0.96 mg per g dry cell weight. The observed shift in zeta potential from −28.95 to −6.25 mV at 0% and 3.5% salinity, respectively, with GB treatment, indicates a reduction in electrostatic repulsion and compaction. Notably, the EPS protein secondary structure transition from β-sheet to α-helix, with GB addition, signifies a more compact protein configuration, less susceptible to salinity fluctuations. Electrochemical analyses, including cyclic voltammetry (CV) and differential pulse voltammetry (DPV), reveal GB's role in promoting the release of exogenous electron shuttles, such as flavins and c-type cytochromes (c-Cyts). The enhancement in DPV peak areas (QDPV) with GB addition implies an increase in available extracellular electron transfer sites. This investigation advances our comprehension of microbial adaptation mechanisms to salinity through EPS modifications facilitated by GB in saline habitats.

Efficient bioremediation of indigo-dye contaminated textile wastewater using native microorganisms and combined bioaugmentation-biostimulation techniques

In this work, the bioremediation of wastewater from the textile industry with indigo dye content was carried out using combined bioaugmentation, bioventilation, and biostimulation techniques. Initially, the inoculum was prepared by isolating the microorganisms from the textile wastewater in a 2 L bioreactor. Then, the respirometry technique was implemented to determine the affinity of the microorganisms and the substrate by measuring CO2 and allowed the formulation of an empirical mathematical model for the growth kinetics of the microorganism. Finally, the bioremediation was carried out in a 3 L bioreactor obtaining an indigo dye removal efficiency of 20.7 ± 1.2%, 24.0 ± 1.5%, and 29.7 ± 1.1% for equivalent wavelengths of 436 nm, 525 nm, and 620 nm. The chemical oxygen demand showed an average reduction of 88.9 ± 2.5%, going from 470.7 ± 15.6 to 52.3 ± 10.7 ppm after 30 days under constant agitation and aeration. A negative generalized exponential model was fitted to assess the affinity of the microorganism with the wastewater as a substrate by evaluating the production of CO2 during the bioremediation. Bioremediation techniques improve water discharge parameters compared to chemical treatments implemented in the industry, reducing the use of substances that can generate secondary pollution. Bioaugmentation, biostimulation, and bioventing of the textile wastewater in this study demonstrate the potential of these combined techniques to serve as an efficient alternative for indigo-contaminated wastewater in the textile industry.

Efficient immobilization of highly stable Bacillus amyloliquefaciens spore laccase for biodecolorization of textile dyes in water

Globally, millions of cubic meters of dye-contaminated wastewater are generated annually from the textile industry. Discharging the dye-contaminated wastewater into natural water streams is detrimental to the ecosystem and human health. Wastewater bioremediation is considered a practical solution for converting wastewater into value-added water for safe reuse especially in irrigation. The present study investigated the immobilization of highly stable spore laccase enzyme of Bacillus amyloliquefaciens A1 by entrapment and adsorption techniques. Based on the results, agarose gel was the most efficient support with 94% immobilization yield. Optimum temperature of immobilized enzyme was at 60 ℃ with complete thermal stability for 120 min. The maximum activity of immobilized enzyme was at pH 6–7 and retained 91% of its activity after 24 h incubation. It showed 100% storage stability after 8 weeks which was higher than that of un-immobilized enzyme (4 weeks). The enzyme activity was nearly stable after 8 consecutive cycles of reuse. Decolorization of 8 textile dyes was studied using the immobilized enzyme. Crystal violet, direct red 81 and acid black 24 were efficiently decolorized (94.5, 77.4, and 68.8%, respectively) within 24 h in the first cycle. Reusability of immobilized enzyme showed 74.6, 53.5, and 51.8% decolorization of the same dyes in the same order after the second cycle. Immobilized spore laccase-treated dye water was used to irrigate lentil seeds and showed germination index about 73% compared to 10.8% for untreated one indicating very low toxicity of the treated dye water.

Livestock wastewater bioremediation through indigenous microalgae culturing as a circular bioeconomy approach as cattle feed

Growing human population demands the enhancement intensive livestock activities, which lead to severe environmental issues like water pollution. Cattle wastewater is rich in some inorganic pollutants, mainly nitrogen and phosphorous, which might constitute a risk to water bodies. Considering this scenario, microalgae's capacity to develop within manure wastewater is attracting interest, mainly for simultaneous wastewater bioremediation and biomass production. The aim of this work was evaluating the response of several microalgae strains to increasing percentages of unsterilized cattle farm wastewater. Moreover, this study also analyses the possibility of enhancing the development of indigenous native microalgal strains, to create a bioremediation system based on previously adapted species, which specific diversity was determined through taxonomic techniques. Two monospecific Chlorophyceae strains were used: Chlorella sp. and Coelastrella cogersae; and one Cyanobacteria strain: Arthrospira platensis. Experimental assays were conducted in 6 groups and triplicates with increasing percentages of Livestock wastewater (LW): control, 15, 25, 35, 50 and 70 %. All the strains tested showed that cattle wastewater represented a source of metabolic stress for microalgae development. Nevertheless, the autochthonous microalgal bloom showed better results in terms of tolerance to wastewater percentage and development under same conditions Laboratory scale results showed that microalgae could develop with optimum results in presence of 15 % of wastewater, reaching absorbance values close to 90 % of the achieved by control cultures. Moreover, indigenous microalgae cultures were scaled up to open type industrial systems (raceways) and influence of their growth on wastewater composition was evaluated. Results showed a severe reduction of the concentration of nitrates to 43.4 (mg·L−1) (20 % of initial measurements). Moreover, the obtained biomass showed a biochemical profile similar to traditional crops, in terms of proteins and carbohydrates (48 and 41 % respectively), suggesting that this biomass could be further valuated into cattle feed as a circular economy approach.

PH-dependent and whole-cell catalytic decolorization of dyes using recombinant dye-decolorizing peroxidase from Rhodococcus jostii.

Dyes in wastewater have adverse effects on the environment and human health. Dye-decolorizing peroxidase (DyP) is a promising biocatalyst to dyes degradation, but the decolorization rates varied greatly which influencing factors and mechanisms remain to be fully disclosed. To explore an effective decolorizing approach, we have studied a DyP from Rhodococcus jostii (RhDyPB) which was overexpressed in Escherichia coli to decolorize four kinds of dyes, Reactive blue 19, Eosin Y, Indigo carmine, and Malachite green. We found the decolorization rates of the dyes by purified RhDyPB were all pH-dependent and the highest one was 94.4% of Malachite green at pH 6.0. ESI-MS analysis of intermediates in the decolorization process of Reactive blue 19 proved the degradation was due to peroxidase catalysis. Molecular docking predicated the interaction of RhDyPB with dyes, and a radical transfer reaction. In addition, we performed decolorization of dyes with whole E. coli cell with and without expressing RhDyPB. It was found that decolorization of dyes by E. coli cell wasdue to both cell absorption and degradation, and RhDyPB expression improved the degradation rates towards Reactive blue 19, Indigo carmine and Malachite green. The effective decolorization of Malachite green and the successful application of whole DyP-overexpressed cells in dye decolorization is conducive to the bioremediation of dye-containing wastewaters by DyPs.

TEXTILE EFFLUENT TREATMENT METHODS AND LIMITATIONS: A SUSTAINABLE AND ECOLOGICAL ASPECT

Industrial wastewater causes water and soil pollution, leading to life-threatening issues. Wastewater comprises several dyes, detergents, phenols, chemical salts, and heavy metals which enhance temperature, pH, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) load, total suspended solids, Total Dissolved Solids (TDS), chlorides, sulfate, and nitrate of affected sites. Dye effluent is highly toxic and leads to mutagenic and carcinogenic outcomes on living beings. Environmental laws are being passed more frequently to control mostly azo-based dyes in the environment. The effluent must be treated before being discarded directly into the ecological ecosystem so that it can be reutilised and recycled for domestic purposes. In the present scenario, using a physicochemical-based approach is inefficient for eliminating contaminants as the process is expensive, and a secondary pollutant, sludge, is produced after the treatment. Being cheap and eco-friendly, the therapy of dye-laden water using microorganisms is a trend. The authors of the current review study have tried to bridge the gap in the bioremediation of dye wastewater. The review imparts an overview of the textile industry, the generation of wastewater by it, the environmental pollution caused, and its impact on the ecosystem. The discussion mainly focuses on the detailed analysis of the last few decades on the decolorisation efficiencies of numerous bioremediation techniques involved in treating textile dye effluent. Additionally, the authors have tried to include the most recent developments in this area. By using eco-friendly methods, this study will undoubtedly help dyestuff companies and researchers.

Microalgae: A Biological Tool for Removal and Recovery of Potentially Toxic Elements in Wastewater Treatment Photobioreactors.

Potentially toxic elements (PTE) pollution in water bodies is an emerging problem in recent decades due to uncontrolled discharges from human activities. Copper, zinc, arsenic, cadmium, lead, mercury, and uranium are considered potentially toxic and carcinogenic elements that threaten human health. Microalgae-based technologies for the wastewater treatment have gained importance in recent years due to their biomass high growth rates and effectiveness. Also, these microalgae-bacteria systems are cost-effective and environmentally friendly, utilize sunlight and CO2, and simultaneously address multiple environmental challenges, such as carbon mitigation, bioremediation, and generation of valuable biomass useful for biofuel production. Additionally, microalgae possess a diverse array of extracellular and intracellular mechanisms that enable them to remove and mitigate the toxicity of PTE present in wastewater. Therefore, photobioreactors are promising candidates for practical applications in bioremediation of wastewater containing toxic elements. Despite the increasing amount of research in this field in recent years, most studies are conducted in laboratory scale and there is a scarcity of large-scale studies under real and variable environmental conditions. Besides, the limited understanding of the multiple mechanisms controlling PTE biosorption in wastewater containing high organic matter loads and potentially toxic elements requires further studies. This chapter provides a schematic representation of the mechanisms and factors involved in the remediation of potentially toxic elements by microalgae, as well as the main results obtained in recent years.

Biorreducción in vitro de cromo hexavalente utilizando consorcios microbianos

Constant industrial development has increased the chromium use, resulting in chromium discharge into wastewater. The implementation of microbial bioremediation has been proposed as an ecological, efficient and economical alternative for the implementation of microorganisms to reduce chromium to a less toxic form. Our objective was to evaluate the Cr (VI) removal capacity of microbial consortia at different concentrations. Accordingly, an activation and identification of microorganisms from chromium-containing wastewater was carried out. Seven microbial consortia were established and their synergy, individual and consortium growth curves were evaluated. Subsequently, a scaled adaptation of the consortia was carried out with eight concentrations of Cr (VI). Reciprocal regression models and growth curves were used to identify the consortium with the highest removal. Synergy was found in the consortia evaluated; growth curves of consortia showed higher absorbance than individually, with higher absorption in the Candida famata-Serratia sp. Consortium. However, in the scaled adaptation, greater Cr (VI) reduction capacity was demonstrated in Candida tropicalis-Serratia sp. with 79.20% at a concentration of 100 ppm with a total chromium reduction of 31.12%. At the same time, a greater adaptation of the consortia to high concentrations of Cr (VI) was identified. This is the first research to report C. tropicalis-Serratia sp. microbial consortium with a positive interaction and higher metabolic reduction capacity, which will have a positive impact on bioremediation of chromium-containing wastewater.

Bioremediation of industrial wastewater: A synergistic approach

Bioremediation of industrial wastewater: A synergistic approach

Mushrooms for enhanced agriculture sustainability – the MUSA concept

The project MUSA – MUshrooms for Sustainable Agriculture is an effort to use mushroom-based processes to enhance agriculture sustainability in Nordic and Baltic countries. The project covers both the production of fruitbodies of edible fungi and the upgrading of the exhausted substrate from mushroom cultivation. The suitability of residues generated locally for producing edible mushrooms is investigated. Residues from Nordic agriculture and sub-utilized streams from forestry management, as well as wood processing by-products, are evaluated as the substrate base for producing shiitake (Lentinula edodes) and oyster (Pleurotus spp.) mushrooms. The project explores the potential of spent mushroom substrate (SMS) to support food production. SMS prospective as source of bioactive compounds and sugars is evaluated. MUSA investigates the suitability of SMS hydrolysates as carbon sources for cultivating oleaginous yeast to produce microbial oil suitable for human consumption. Using SMS for substituting mineral fertilizers and providing wastewater bioremediation solutions is also assessed.

Beneficiation of paper-pulp industrial wastewater for improved outdoor biomass cultivation and biodiesel production using Tetradesmus obliquus (Turpin) Kützing

Algae-based wastewater bioremediation offers a cost-effective method for sustainably treating wastewater while simultaneously addressing global water scarcity and pollution. This study highlights the benefits of treating primary-treated (PTW) and secondary-treated (STW) paper-pulp industrial wastewaters using the microalga Tetradesmus obliquus (Turpin) Kützing. A batch culture study revealed that 50 % secondary treated wastewater can increase the biomass yield 1.8 fold to 2.51 g L−1 in 15 days with a corresponding lipid yield of 390.2 mg L−1. Upscaling this work in 200 L open raceway ponds with 50 % STW as the growth medium showed areal biomass and lipid productivities of 26.80 and 3.90 g m−2 day−1, respectively, in 15 days at 20 cm culture depth. This translates to a projected high annual biomass productivity of approximately 85.0 tons hectare−1 year−1 based on datasets spanning two consecutive years. Bioremediation efficiencies of 80.0 %, 91.51 %, and 92.10 % were achieved for COD, TOC, and NH4+ respectively. Biodiesel produced showed a large percentage of saturated and monounsaturated fatty acids (∼90 %) and its fuel properties complied with the global biodiesel standards. This study thus shows that using paper-pulp industrial wastewater for algal growth offers a sustainable solution for energy generation and wastewater treatment, with significant implications for environmental sustainability.