Microalgae biofilm cultured in nutrient-rich water as a tool for the phycoremediation of petroleum-contaminated water

Using PyCaret to model Chlorella vulgaris's growth response to salinity and oil contamination for crude oil bioremediation

Crude oil spills significantly impact aquatic ecosystems, necessitating innovative remediation strategies. Microalgae-based bioremediation, particularly with Chlorella vulgaris, offers a promising solution. This study introduces a novel framework that evaluates the combined effects of selected environmental stressors on microalgal adaptability, advancing beyond traditional isolated factor analyses. By integrating a factorial experimental design with a machine learning approach using PyCaret AutoML and SHAP values, we provide a detailed examination of how crude oil concentration, salinity, and exposure duration affect C. vulgaris growth. The Extra Trees Regressor model emerged as highly accurate in predicting biomass concentration, a crucial adaptability indicator, achieving an MAE of 0.0202, RMSE of 0.029, and an R² of 0.8875. SHAP analysis highlighted salinity and crude oil as significant growth influencers, with exposure duration playing a minor role. Notably, C. vulgaris exhibited more sensitivity to salinity than to crude oil, indicating potential high-salinity challenges but also a strong tolerance to oil pollutants. These findings enhance our understanding of microalgal responses in polluted environments and suggest improved bioremediation approaches for saline waters affected by oil spills, leveraging the synergy of environmental factors and machine learning insights.

Antibiotic synergistic effect surge bioenergy potential and pathogen resistance of Chlorella variabilis biofilm

Tetracycline (TC) and ciprofloxacin (CF) induce a synergistic effect that alters the biochemical composition, leading to a decrease in the growth and photosynthetic efficiency of microalgae. But the current study provides a novel insight into stress-inducing techniques that trigger a change in macromolecules, leading to an increase in the bioenergy potential and pathogen resistance of Chlorella variabilis biofilm. The study revealed that in a closed system, a light intensity of 167 μmol/m2/s causes 93.5% degradation of TC and 16% degradation of CF after 7 days of exposure, hence availing the products for utilization by C. variabilis biofilm. The resistance to pathogens invasion was linked to 85% and 40% increase in the expression level of photosystem II oxygen-evolving enhancer protein 3 (PsbQ), and mitogen activated kinase (MAK) respectively. The results also indicate that a surge in light intensity triggers 49% increase in the expression level of lysophosphatidylcholine (LPC) (18:2), which is an important lipidomics that can easily undergo transesterification into bioenergy. The thermogravimetric result indicates that the biomass sample of C. variabilis biofilm cultivated under light intensity of 167 μmol/m2/s produces a higher residual mass of 45.5% and 57.5 under air and inert conditions, respectively. The Fourier transform infrared (FTIR) indicates a slight shift in the major functional groups, while the energy-dispersive X-ray spectroscopy (SEM-EDS) and X-ray fluorescence (XRF) indicate clear differences in the morphology and elemental composition of the biofilm biomass in support of the increase bioenergy potential of C. variabilis biofilm. The current study provides a vital understanding of a innovative method of cultivation of C. variabilis biofilm, which is resistant to pathogens and controls the balance between fatty acid and TAG synthesis leading to surge in bioenergy potential and environmental sustainability.

Understanding the role of biofilms and estimation of life-span of a tire derived aggregates-based underground stormwater treatment system

The importance of biofilm in tire derived aggregates (TDA) based underground systems has been investigated in this paper, to assess the utilization of tire waste as a cost-effective and sustainable resource for stormwater treatment. The primary objective of this study is to look into the role of biofilms in preventing metal leaching from a TDA based stormwater treatment system and to estimate the life span of a TDA based stormwater treatment system. TDA subjected to different influents to promote or limit the growth of biofilms were analyzed for their leaching and adsorption potential for fifteen different metals through 72 flushes, which is representative of roughly 9 years of TDA exposure to storm events in the upper Midwest USA. Biofilm growth on a manufacturing byproduct (wire exposed-TDA) was higher than on the traditional TDA. The presence of biofilm on TDA had a minor impact on orthophosphate adsorption as observed in a previous study conducted by the authors. However, metals such as iron, zinc and copper, which were previously a concern, had substantially lower leaching into the stored runoff. In addition, the orthophosphate removal from runoff by TDA with a biofilm through 72 flushes indicates that TDA based underground systems can have orthophosphate removal life span beyond 8-9 years. Thus, TDA with biofilms in an underground storage/infiltration chamber has the potential to establish itself as a sustainable, cost-effective, and long life-span alternative for stormwater remediation of orthophosphate pollution without leaching of metals.

Bioaccumulation of arsenic in fish (Labeo rohita) in presence of periphyton: ameliorative effect on oxidative stress, physiological condition, immune response and risk assessment

The present study explores the use of periphyton to ameliorate toxic properties of arsenic (As) to Labeo rohita and also assesses the human food safety aspects. Fish were introduced to arsenite [As(III)] contaminated water (0.3 and 3 mg/L) along with periphyton. Biochemical, physiological and immunological parameters, including gene expression, were assessed after 30 days of exposure. Periphyton incorporation significantly improved (p < 0.05) the adverse effects of As on respiration, NH3 excretion and brain AChE activity by reducing oxidative stress and As bioaccumulation. The presence of periphyton in As(III) exposed fish (3 mg/L) increased the immune response (Immunoglobulin M and Complement C3) in the serum and the regulation of the respective immune genes in the anterior kidney was found to be similar to the control. A speciation study using LC-ICP-MS confirmed the high accumulation of As by periphyton (5.0-31.9 μg/g) as arsenate [As (V)], resulting in a lower amount of As in fish muscle. The calculated human health risk indices, Target Hazard Quotient (THQ) and Target Cancer risk (TCR) indicate that fish grown in periphyton-treated water may lower the human health risks associated with As. The study signifies the importance of periphyton-based aquaculture systems in As contaminated regions for safe fish production with enhanced yield.

Microbial remediation of petroleum-contaminated soil focused on the mechanism and microbial response: a review

The environmental pollution caused by petroleum hydrocarbons has received considerable attention in recent years. Microbial remediation has emerged as the preferred method for the degradation of petroleum hydrocarbons, which is experiencing rapid development driven by advancements in molecular biology. Herein, the capacity of different microorganisms used for crude oil bioremediation was reviewed. Moreover, factors influencing the effectiveness of microbial remediation were discussed. Microbial remediation methods, such as bioaugmentation, biostimulation, and bioventilation, are summarized in this review. Aerobic and anaerobic degradation mechanisms were reviewed to elucidate the metabolic pathways involved. The impacts of petroleum hydrocarbons on microorganisms and the environment were also revealed. A brief overview of synthetic biology and a unique perspective of technique combinations were presented to provide insight into research trends. The challenges and future outlook were also presented to stimulate contemplation of the mechanisms involved and the development of innovative techniques.

Bioremediation for the recovery of oil polluted marine environment, opportunities and challenges approaching the Blue Growth

The Blue Growth strategy promises a sustainable use of marine resources for the benefit of the society. However, oil pollution in the marine environment is still a serious issue for human, animal, and environmental health; in addition, it deprives citizens of the potential economic and recreational advantages in the affected areas. Bioremediation, that is the use of bio-resources for the degradation of pollutants, is one of the focal themes on which the Blue Growth aims to. A repertoire of marine-derived bio-products, biomaterials, processes, and services useful for efficient, economic, low impact, treatments for the recovery of oil-polluted areas has been demonstrated in many years of research around the world. Nonetheless, although bioremediation technology is routinely applied in soil, this is not still standardized in the marine environment and the potential market is almost underexploited. This review provides a summary of opportunities for the exploiting and addition of value to research products already validated. Moreover, the review discusses challenges that limit bioremediation in marine environment and actions that can facilitate the conveying of valuable products/processes towards the market.

Efficient treatment of tannery wastewater through aeration, coagulation, and algal pond

BACKGROUND

Tannery wastewater effluents contain many toxic and carcinogenic heavy metals and physiochemical parameters that need to be removed before these effluents enter in the main water bodies or rivers. In this study, the effluents from the tannery industry are treated through aeration, coagulation, and Chlorella vulgaris pond treatment processes for the removal of physiochemical: parameters only.

METHODS

The effect of removal efficiencies (%) was studied on the physicochemical parameters, including salinity, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD).

RESULTS

The key results showed that the removal of EC, TDS, turbidity, TSS, BOD, and COD was 80.2%, 67%, 81%, 80.8%, 68.6%, and 100%, respectively, in raw wastewater treatment having 25, 50, and 70 g of algae C. vulgaris doses. The removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 83%, 87.1%, 77.1%, 80%, 40%, 97%, and 98%, respectively, during coagulated wastewater treatment with three doses of algae. The observed improvement in treated wastewater indicated that the removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 85.7%, 39.3%, 81.3%, 67.8%, 50.3%, 97%, and 98%, with C. vulgaris.

CONCLUSION

This study confirmed that the treatment of tannery wastewater by these processes increased the pollutant removal efficiencies as all the physiochemical parameters were exceeding the permissible limits.

RESULTS CONTRIBUTION IN FUTURE

This research will be helpful to treat the industrial wastewaters or effluents before it further mixes up in the main water streams. In this way, water quality will be better, aquatic life will be saved, and further researchers can analyze more ways for efficient treatments as they have a baseline data through this study findings.

PRACTITIONER POINTS

One of the most pollutant sources in terms of both physical and chemical parameters is the produced wastewater from tannery industries. The effluents from tannery industry are treated through aeration, coagulation, and algae ponds treatment processes. These treatment made the tannery wastewater as environmental friendly.

A review of microalgae biofilm as an eco-friendly approach to bioplastics, promoting environmental sustainability

In this comprehensive review, we delve into the challenges hindering the large-scale production of microalgae-based bioplastics, primarily focusing on economic feasibility and bioplastic quality. To address these issues, we explore the potential of microalgae biofilm cultivation as a sustainable and highly viable approach for bioplastic production. We present a proposed method for producing bioplastics using microalgae biofilm and evaluate its environmental impact using various tools such as life cycle analysis (LCA), ecological footprint analysis, resource flow analysis, and resource accounting. While pilot-scale and large-scale LCA data are limited, we utilize alternative indicators such as energy efficiency, carbon footprint, materials management, and community acceptance to predict the environmental implications of commercializing microalgae biofilm-based bioplastics. The findings of this study indicate that utilizing microalgae biofilm for bioplastic production offers significant environmental sustainability benefits. The system exhibits low energy requirements and a minimal carbon footprint. Moreover, it has the potential to address the issue of wastewater by utilizing it as a carbon source, thereby mitigating associated problems. However, it is important to acknowledge certain limitations associated with the method proposed in this review. Further research is needed to explore and engineer precise techniques for manipulating microalgae biofilm structure to optimize the accumulation of desired metabolites. This could involve employing chemical triggers, metabolic engineering, and genetic engineering to achieve the intended goals. In conclusion, this review highlights the potential of microalgae biofilm as a viable and sustainable solution for bioplastic production. While acknowledging the advantages, it also emphasizes the need for continued synthetic studies to enhance the efficiency and reliability of this approach. By addressing the identified drawbacks and maximizing the utilization of advanced techniques, we can further harness the potential of microalgae biofilm in contributing to a more environmentally friendly and economically feasible bioplastic industry.

Exploring the bioremediation capability of petroleum-contaminated soils for enhanced environmental sustainability and minimization of ecotoxicological concerns

The bioremediation of soils contaminated with petroleum hydrocarbons (PHCs) has emerged as a promising approach, with its effectiveness contingent upon various types of PHCs, i.e., crude oil, diesel, gasoline, and other petroleum products. Strategies like genetically modified microorganisms, nanotechnology, and bioaugmentation hold potential for enhancing remediation of polycyclic aromatic hydrocarbon (PAH) contamination. The effectiveness of bioremediation relies on factors such as metabolite toxicity, microbial competition, and environmental conditions. Aerobic degradation involves enzymatic oxidative reactions, while bacterial anaerobic degradation employs reductive reactions with alternative electron acceptors. Algae employ monooxygenase and dioxygenase enzymes, breaking down PAHs through biodegradation and bioaccumulation, yielding hydroxylated and dihydroxylated intermediates. Fungi contribute via mycoremediation, using co-metabolism and monooxygenase enzymes to produce CO2 and oxidized products. Ligninolytic fungi transform PAHs into water-soluble compounds, while non-ligninolytic fungi oxidize PAHs into arene oxides and phenols. Certain fungi produce biosurfactants enhancing degradation of less soluble, high molecular-weight PAHs. Successful bioremediation offers sustainable solutions to mitigate petroleum spills and environmental impacts. Monitoring and assessing strategy effectiveness are vital for optimizing biodegradation in petroleum-contaminated soils. This review presents insights and challenges in bioremediation, focusing on arable land safety and ecotoxicological concerns.

Microalgae biofilm system as an efficient tool for wastewater remediation and potential bioresources for pharmaceutical product production: an overview

The role of microalgae in wastewater remediation and metabolite production has been well documented, but the limitations of microalgae harvesting and low biomass production call for a more sustainable method of microalgae utilization. The current review gives an insight on how microalgae biofilms can be utilized as a more efficient system for wastewater remediation and as potential source of metabolite for pharmaceutical product production. The review affirms that the extracellular polymeric substance (EPS) is the vital component of the microalgae biofilm because it influences the spatial organization of the organisms forming microalgae biofilm. The EPS is also responsible for the ease interaction between organisms forming microalgae biofilm. This review restate the crucial role play by EPS in the removal of heavy metals from water to be due to the presence of binding sites on its surface. This review also attribute the ability of microalgae biofilm to bio-transform organic pollutant to be dependent on enzymatic activities and the production of reactive oxygen species (ROS). The review assert that during the treatment of wastewater, the wastewater pollutants induce oxidative stress on microalgae biofilms. The response of the microalgae biofilm toward counteracting the stress induced by ROS leads to production of metabolites. These metabolites are important tools that can be harness for the production of pharmaceutical products.

The role of microorganisms in petroleum degradation: Current development and prospects

Petroleum hydrocarbon compounds are persistent organic pollutants, which can cause permanent damage to ecosystems due to their biomagnification. Bioremediation of oil is currently the main solution for the remediation of petroleum hydrocarbon pollutants in ecosystems. Despite several lab studies on oil microbial biodegradation efficiency, still there are various challenges for microorganisms to perform efficiently in outside environments. Herewith, investigating efficient biodegradation technologies through discovering new microorganisms, biodegradation pathways modification, and new bioremediations technologies are in great demand. The degradation of petroleum pollutants by microorganisms and the remediation of contaminated soils are achieved through their key enzymes and metabolic pathways. Although, several challenges hinder the effective biodegradation processes such as the toxic environment, long chains and versatility of petroleum hydrocarbons and the existence of the full metabolism pathways in a single microorganism. There are several developed oil biodegradation strategies by microorganisms such as synthetic biology, biofilm, recombinant technology and microbial consortia. Herewith, the application of multi-omics technology to discover oil-contaminated environments microbial communities, synthetic biology, microbial consortia, and other technologies would help improve the efficiency of microbial remediation.

Microalgal extract as bio-coating to enhance biofilm growth of marine microalgae on microporous membranes

Microalgal biofilm is a popular platform for algal production, nutrient removal and carbon capture; however, it suffers from significant biofilm exfoliation under shear force exposure. Hence, a biologically-safe coating made up of algal extracellular polymeric substances (EPS) was utilized to secure the biofilm cell retention and cell loading on commercial microporous membrane (polyvinylidene fluoride), making the surfaces more hydrophobic (contact angle increase up to 12°). Results demonstrated that initial cell adhesion of three marine microalgae (Amphora coffeaeformis, Cylindrotheca fusiformis and Navicula incerta) was enhanced by at least 1.3 times higher than that of pristine control within only seven days with minimized biofilm exfoliation issue due to uniform distribution of sticky transparent exopolymer particles. Bounded extracellular polysaccharide gathered was approximately 23% higher on EPS-coated membranes to improve the biofilm's hydraulic resistance, whereas bounded extracellular protein would only be substantially elevated after the attached cells re-accommodate themselves onto the EPS pre-coating of themselves. In accounting the rises of hydrophobic protein content, biofilm was believed to be more stabilized, presumably via hydrophobic interactions. EPS biocoating would generate a groundswell of interest for bioprocess intensifications though there are lots of inherent technical and molecular challenges to be further investigated in future.

Biofilm-mediated bioremediation is a powerful tool for the removal of environmental pollutants

Biofilm-mediated bioremediation is an attractive approach for the elimination of environmental pollutants, because of its wide adaptability, biomass, and excellent capacity to absorb, immobilize, or degrade contaminants. Biofilms are assemblages of individual or mixed microbial cells adhering to a living or non-living surface in an aqueous environment. Biofilm-forming microorganisms have excellent survival under exposure to harsh environmental stressors, can compete for nutrients, exhibit greater tolerance to pollutants compared to free-floating planktonic cells, and provide a protective environment for cells. Biofilm communities are thus capable of sorption and metabolization of organic pollutants and heavy metals through a well-controlled expression pattern of genes governed by quorum sensing. The involvement of quorum sensing and chemotaxis in biofilms can enhance the bioremediation kinetics with the help of signaling molecules, the transfer of genetic material, and metabolites. This review provides in-depth knowledge of the process of biofilm formation in microorganisms, their regulatory mechanisms of interaction, and their importance and application as powerful bioremediation agents in the biodegradation of environmental pollutants, including hydrocarbons, pesticides, and heavy metals.

Arthrospira sp. mediated bioremediation of gray water in ceramic membrane based photobioreactor: process optimization by response surface methodology

Direct discharge of raw domestic sewage enriched with nitrogenous and phosphorous compounds into the water bodies causes eutrophication and other environmental hazards with detrimental impacts on public and ecosystem health. The present study focuses on phycoremediation of gray water with Arthrospira sp. using an innovative hydrophobic ceramic membrane-based photobioreactor system integrated with CO₂ biofixation and biodiesel production, aiming for green technology development. Surfactant and oil-rich gray water collected from the domestic kitchen was used wherein, chloride, sulfate, and surfactant concentrations were statistically optimized using response surface methodology (RSM), considering maximum microalgal growth rate as a response for the design. Ideal concentrations (mg/L) of working parameters were found to be 7.91 (sulfate), 880.49 (chloride), and 144.02 (surfactant), respectively to achieve optimum growth rate of 0.43 g_dwt/L/day. Enhancement of growth rate of targeted microalgae by 150% with suitable CO₂ (19.5%) supply and illumination in the photobioreactor affirms its efficient operation. Additionally, harvested microalgal biomass obtained from the process showed a biodiesel content of around 5.33% (dry weight). The microalgal treatment enabled about 96.82, 87.5, and 99.8% reductions in BOD, COD, and TOC, respectively, indicating the potential of the process in pollutant assimilation and recycling of such wastewater along with value-added product generation.