Lutein is a xanthophyll carotenoid widely recognized for its roles in eye health, antioxidant and neuroprotective effects, and the prevention of oxidative stress-related disorders. The growing demand for functional foods and nutraceuticals has heightened industry interest in sustainable lutein production. However, conventional sources such as green vegetables and marigold flowers face several limitations, including low bioavailability, seasonal variability, land-intensive cultivation, and sustainability concerns. Therefore, this review provides an updated, comprehensive, and integrated overview of sustainable lutein production, extraction technologies, and functional applications. This review discusses conventional dietary sources alongside emerging alternative platforms, including microalgae, agro-industrial byproducts, and bioengineered fermentation systems. Recent advances in green extraction technologies, particularly supercritical CO2, ultrasound-assisted, and enzyme-assisted extraction, are also critically evaluated due to their potential to improve extraction efficiency while reducing environmental impact. In addition, the applications of lutein in functional foods, nutraceuticals, and pharmaceutical products are also highlighted. This review further examines key technical challenges, including low bioavailability, high production and downstream processing costs, compound instability, extraction inefficiencies, lack of standardization, and scalability limitations. Future progress will depend on integrating circular bioeconomy strategies, artificial intelligence (AI)-assisted process optimization, sustainable biorefinery concepts, and advanced stabilization technologies to support economically viable and environmentally sustainable lutein production systems.

Surfactant adsorption on reservoir rock is a major limitation in chemical enhanced oil recovery (EOR) because it reduces effective surfactant concentration and increases chemical loss. In this study, a sodium lignosulfonate (SLS)-silica nanoparticle (SNP) system was investigated on Buff Berea Sandstone (BBS) at different temperature mitigations to evaluate its potential for adsorption. Residual surfactant concentration was determined by UV-Vis spectrophotometry at 208 nm, yielding excellent linearity R2 = 0.9948. Adsorption equilibrium was analyzed using Langmuir and the Freundlich isotherm models, while kinetics were evaluated using pseudo-first-order (PFO) and pseudo-second-order (PSO) models. At 30 °C, adsorption was best described by the Langmuir model (R2 = 0.9619, SSE = 2.09, whereas at 60 °C, the Freundlich model gave the best fit (R2 = 0.8220, SSE = 0.36). The optimum SNP concentration increased from 1000 to 1500 mg/L at 30 °C to 2000–2500 mg/L at 60 °C, likely due to elevated temperature, which enhanced molecular mobility and interfacial heterogeneity, thereby requiring more SNPs to cover or shield active adsorption sites on BBS. Kinetic results consistently favored the PSO model. These findings show that SNPs effectively reduce SLS adsorption and modify the adsorption behavior in a temperature-dependent manner, providing useful insight for the design of more efficient chemical-enhanced oil recovery formulations.

Artificial sweeteners have emerged as contaminants of increasing concern due to their widespread consumption, environmental persistence, and resistance to conventional wastewater treatment. This review provides an integrated assessment of global research trends and the environmental behavior of major artificial sweeteners, including sucralose, acesulfame potassium, saccharin, and aspartame. Bibliometric analysis of SCOPUS-indexed publications reveals rapid growth in research since 2010, with key themes focusing on environmental occurrence, treatment technologies, and ecotoxicological effects. These compounds are frequently detected in wastewater effluents, surface waters, groundwater, and even drinking water systems, driven by their high solubility and limited biodegradability. Their persistence raises concerns regarding ecological impacts, including potential alterations to microbial communities and aquatic organisms. In addition, emerging evidence suggests potential human health implications, including gut microbiota disruption, metabolic effects, and risks associated with chronic low-dose exposure, although these remain poorly understood. The performance of existing treatment technologies, including biological processes, adsorption, advanced oxidation, and membrane filtration, is critically evaluated, highlighting limitations in complete removal and in the formation of transformation products. Future research should prioritize sustainable treatment strategies, comprehensive risk assessment, and improved monitoring frameworks to better address both environmental and human health risks associated with artificial sweeteners.

Rapid urbanization and population growth have increased sewage generation, creating major environmental and public health challenges, particularly in regions lacking centralized treatment. Conventional systems are effective but costly and energy-intensive, limiting decentralized deployment. Integrating water hyacinth (Eichhornia crassipes) into hydroponic systems offers a low-cost, nature-based alternative for nutrient and organic removal. This review makes three key contributions: (i) it defines a quantitative design–performance envelope linking hydraulic retention time, plant density, and harvesting frequency to treatment efficiency; (ii) it reframes biomass harvesting as a core process control governing net nitrogen and phosphorus removal and root-zone oxygen dynamics; and (iii) it integrates reactor design, biosecurity, and biomass valorization into a unified framework for decentralized sewage treatment. Synthesis of 220 studies shows that controlled floating hydroponic systems typically achieve 50–90% total nitrogen, 60–95% total phosphorus, and 60–95% BOD removal at 7–30 days HRT, driven by coupled plant uptake, rhizosphere nitrification–denitrification, and biofilm adsorption. Pathogen removal is generally limited to 0.5–2 log reductions for indicator bacteria (total and faecal coliforms/Escherichia coli), indicating that post-treatment polishing (UV, chlorination, maturation ponds, or wetlands) is required depending on the intended reuse or discharge standard. Performance declines below 15°C without greenhouse protection or hybridization with conventional biological units. Key constraints include seasonal metabolic limitations, hydraulic sensitivity to shock loading, invasive escape risks, and the need for standardized protocols for metal-laden biomass management. Proposed solutions include adaptive harvesting regimes, modular plug-flow layouts, hybrid treatment trains, and biochar production to stabilize contaminants and enable carbon sequestration. Positioned between passive wetlands and energy-intensive membrane systems, water hyacinth hydroponics offers moderate land demand, low energy use (0.02–0.1 kWh m⁻³), and circular bioeconomy potential for scalable decentralized sewage treatment.

Sustainable xanthan gum (XG) production is increasingly prioritized as global demand rises, and conventional processes face economic and environmental constraints. Traditional manufacturing depends heavily on refined sugars, intensive fermentation control, and solvent-based purification, which elevate production costs and ecological impact. This review highlights recent advancements designed to improve sustainability across the XG value chain, focusing on alternative substrates, optimized fermentation, and greener extraction methods. Agricultural residues, food-processing waste, lignocellulosic biomass, and industrial effluents have emerged as promising low-cost substrates that reduce reliance on refined sugar sources while supporting waste valorization. Pretreatment strategies, such as acid hydrolysis, enzymatic processing, and integrated biological–chemical methods, significantly enhance the accessibility of complex biomass for microbial fermentation. Concurrently, improvements in strain selection, metabolic engineering, and process control have increased XG yield, molecular weight, and rheological performance. Environmentally friendly extraction technologies, including ultrasound-assisted extraction, pulsed electric fields, membrane filtration, and electro-dewatering, further reduce solvent consumption and energy demand in downstream processing. However, challenges persist, including substrate variability, formation of inhibitory compounds, strain instability, and regulatory considerations for waste-derived substrates or genetically modified strains. Future progress will rely on integrating bioprocess intensification, genetic engineering, and techno-economic assessment to build scalable, low-impact, and circular XG production systems.

Ports play a pivotal role in global trade but are also associated with significant environmental and social challenges. Despite growing research on green ports, existing studies remain fragmented, with limited integration between technological, environmental, and governance perspectives within the blue economy framework. This review examines the transition from green port initiatives toward integrated blue-economy-oriented port systems by synthesizing recent advances in sustainable maritime infrastructure, smart port technologies, renewable energy integration, and policy frameworks. The analysis reveals three major findings. First, ports are increasingly evolving into energy-integrated hubs, with leading examples adopting shore power systems, renewable energy microgrids, and hydrogen-based infrastructure, thereby contributing to emissions reductions. Second, digitalization through artificial intelligence, IoT, and data-driven logistics significantly enhances operational efficiency, reduces energy consumption, and improves real-time decision-making. Third, effective governance frameworks that combine regulatory measures and incentive-based instruments are critical to accelerating sustainability transitions while ensuring economic competitiveness. In addition, the review highlights the growing integration of biodiversity conservation, marine pollution mitigation, and community engagement into port management strategies, reflecting a shift toward ecosystem-based approaches. Overall, the findings demonstrate that ports are transitioning from conventional logistics hubs into integrated socio-technical systems that enable low-carbon maritime transport while supporting inclusive and resilient coastal development.

Treatment of wastewater effluent is essential to reduce environmental impact and keep surface water clean, meeting sustainable criteria. While plant-based coagulants are known for their eco-friendly profiles, their dual application for high-efficiency nutrient removal and subsequent sludge valorization in fish farm systems remain under-explored. Therefore, this study was conducted to determine the optimum conditions for using natural coagulants to recover nutrients from fish farm effluent. Two types of natural coagulants, Alhagi graecorum leaves and apricot seeds, were evaluated for the treatment and recovery of nutrients from fish farm effluent due to their high removal efficiency, non-toxicity, and cost-effectiveness. In this study, optimization was performed using Response Surface Methodology (RSM) with a Central Composite Design (CCD) to investigate the effects of three factors: coagulant concentration (1000–7000 mg/L), wastewater pH (5–9), and settling time (15–35 min). The primary responses measured were the removal efficiencies of phosphate (PO4) and nitrate (NO3). According to the CCD results, maximum removal efficiencies reached 92.63% and 73.49% for PO4 and NO3, respectively. The optimal conditions were identified as pH 5, 1000 mg/L coagulant concentration, and a 35 min settling time for A. graecorum, and pH 9, 1000 mg/L concentration, and a 15 min settling time for apricot seed. These findings establish the optimal conditions for using these natural substances as effective agents for sustainable wastewater treatment and nutrient recovery.

A 2-acre reedbed system, cultivated with Phragmites australis, was established and utilized to remediate groundwater polluted with chlorinated hydrocarbons at a former industrial site. The reedbed comprised a combination of horizontal and vertical systems over four parallel installations, with a treatment capacity of 305 m ³/day. The mean inlet concentration for the four-line treatment was 112.4 mg/L, which was below the specified inlet concentration of 250 mg/L. From 2019 to 2024, the reedbed system effectively eliminated 1,2-Dichloroethane (1,2-DCA), with average removal rates of 97.7%, 98.8%, 98.5%, and 98.6% for Lines 1 to 4, respectively. The average outlet concentrations of 1,2-DCA were 0.70 mg/L, 0.40 mg/L, 0.42 mg/L, and 0.52 mg/L for Lines 1–4, respectively, resulting in an overall average of 0.51 mg/L. We performed the assessment of natural attenuation by first-order decay kinetics for five groundwater monitoring wells, showing values between 0.0012/year and 0.0036/year (shallow wells), 0.0003/year and 0.0021/year (middle wells), and 0.0003/year and 0.0009/year (deep wells). Here, shallow groundwater showed the highest kinetic rates compared to middle and deep groundwater wells. The results indicated that the reedbed system removed the bulk of contaminants through active biological processes involving plants and microbes, and that natural attenuation further degraded 1,2-DCA in the groundwater profiles. Based on data monitoring from 2019 to 2024, the reduction and degradation results showed good removal efficiency for the reedbed systems, combined with natural attenuation in the groundwater.

Fisheries wastewater contains high levels of suspended solids and organic matter, posing significant environmental risks and necessitating effective and sustainable treatment approaches. This study aims to determine the characteristics of the neem (Azadirachta indica) leaf biocoagulant, assess the interactions among research variables, and optimize its use to reduce total suspended solids (TSS) and chemical oxygen demand (COD) levels in fisheries wastewater. The method used is response surface methodology (RSM), specifically the Box–Behnken Design (BBD), which involves three variables (biocoagulant concentration, fast stirring speed, and sedimentation time) and two responses (TSS and COD removal). Characterization results (Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and zeta potential) indicated that the biocoagulant contains functional groups such as hydroxyl, carboxyl, and amine, contributing to coagulation–flocculation through adsorption and polymer bridging mechanisms. Statistical analysis confirmed that the developed quadratic models were significant (p-value < 0.05), with high F-values, non-significant lack of fit, and strong coefficients of determination (R² = 0.9111 for TSS and 0.9419 for COD), along with low coefficients of variation (CV < 5%), indicating good model reliability. Although the model generally has a significant effect on the response, the fast stirring speed does not, while the other two factors do. The optimal conditions (based on desirability) were determined to be a biocoagulant concentration of 79.8 mg/L, a fast stirring speed of 100 rpm, and a sedimentation time of 27.5 min. Under these conditions, TSS and COD removals of 88.72% and 79.98%, respectively, were achieved. These findings demonstrate the potential of neem leaf biocoagulant as a sustainable, environmentally friendly alternative to conventional chemical coagulation, supporting cleaner production in aquaculture systems.

The use of plants as biocoagulants in water/wastewater treatment is currently emerging. This review article explores the potential of each plant's part functioning as a biocoagulant for pollutant removal. Bibliometric analysis was employed to analyze the development of research in natural and biocoagulants, while descriptive analysis was used to clearly juxtapose the performance of each plant's part in treating water/wastewater. Bibliometric findings reveal a high increment in the publication of natural coagulants in the year 2016. The keywords of flocculation, pH, turbidity, and water purification are mentioned to be the closest node related to the coagulation. Comparison between plant parts showed that research on seeds is dominating the previous literature (26.31 %), followed by leaves (10.89 %) and peels (5.75 %). Overall performance analysis showed that plant biocoagulants are superior in removing turbidity (median 83.45 %), while the performance of removing total suspended solids, chemical oxygen demand, and biological oxygen demand are also considerably good (mean 68.38 %, 71.36 %, 67.16 %, respectively). The seeds and other parts of the plants showed the highest removal of turbidity among other parts (mean of removal 90 % and median >90 %). Other parts of the plants are composed mostly of plant extracts, including mucilage (18.47 %), gum (9.67 %), starch (8.36 %), etc. (10.37 %). Overall, the effectiveness of plant biocoagulants in removing pollutants varies compared to that of commercially available coagulants. The current development of biocoagulants indicates that research is currently in the integration and hybridization stage. Future approaches are suggested to focus on upscaling the treatment to an industrial scale, simplifying the extraction procedures, and conducting species-specific analysis to enhance and polish the current knowledge of plant bicocoagulants in water/wastewater treatment.

Microalgae-based wastewater treatment is an alternative to physico-chemical and bacteria-based technologies. Microalgae-based wastewater treatment showed enormous potential, not only exhibiting excellent pollutant removal efficiencies but also unlimited opportunities for resource recovery. Despite its promising future, the question of selecting autotrophy or heterotrophy regimes for optimal organic pollutant removal remains. This current work juxtaposes the performance of autotrophic and heterotrophic cultures in treating organic-rich wastewater to shed light on the unsolved puzzle. This review paper details the autotrophy and heterotrophy growth regimes for microalgae, as well as highlights the source of organic-rich wastewater and its characteristics. A clear comparison between both regimes was then discussed with recent references. Heterotrophic cultures showed better parameter removal performances, especially carbon-related and N-related compounds, while the removal of P-related compounds is considerably similar. Heterotrophic regimes also resulted in higher biomass yield with higher P content as compared to autotrophy. Despite their superiority, heterotrophic regimes continuously require additional carbon sources, posing a cost-related limitation. In contrast, autotrophic culture has an added value of carbon sequestration, making it beneficial for climate mitigation and lowering operational costs. Future research should concentrate on techno-economic and cost-benefit analyses to further refine the currently discussed topic.

Hexavalent chromium is one of the toxic metals in water pollution. This study is aimed at analyzing the involvement of chromium reductase and biosorption potential in chromium-resistant species of Bacillus cereus. A total of 10 % (v/v) of B. cereus biomass was inoculated into a 90 mL chromium-contaminated solution with an initial concentration of 60 mg/L. Biomass digestion was carried out every day for a 5-day treatment period for chromium content analysis, while biomass characterization was carried out at the end of the treatment period, comparing the exposed vs. non-exposed bacteria. Results indicated that the highest chromium removal (16.12 ± 0.63 %) was obtained on day 3, while the maximum biosorption capacity was obtained on day 1, reaching 0.461 ± 0.02 mg Cr/g dry cell of biomass. XRD showed the crystalline structure of the bacteria cell after being exposed to chromium, suggesting that interactions between polysaccharides and proteins in the membrane may occur during the treatment. In addition, FT-IR spectra also showed decreasing peaks and the involvement of hydroxyl, carboxyl, carbonyl, and nitroxide groups during the treatment. SEM-EDX results indicated that bacteria are experiencing cell structure alteration with more intense chromium spectra on the surface, while TEM images showed endospore formation by B. cereus under adverse environmental conditions. This study suggested that the removal of hexavalent chromium by B. cereus might be dominant via biosorption (translocated into cell biomass).

Proteins and carbohydrates are both major biodegradable fractions in wastewater. Complexation with coexisting compounds, such as iron (Fe) and humic acids (HA), which are both commonly present in wastewater, could influence the different degradation rates of proteins and carbohydrates. Depending on the redox conditions, Fe exists as Fe(II) or Fe(III), with differing binding affinities and chemical behaviour. This research aims to systematically assess the complex interaction between Fe, protein, and HA compounds under aerobic and anaerobic conditions. The results showed that the addition of Fe(III) and HA to a protein solution inhibited its hydrolysis rate by more than 90 % under aerobic conditions. In contrast, interactions between the same compounds and carbohydrates were much weaker and had a minimal effect on hydrolysis rates. Complexation with Fe, proteins, and HA was indicated by increased molecular sizes and reduced concentrations of free iron, protein, and HA. FTIR results showed that Fe(III) formed complexes with proteins and HA through electrostatic and coordination bonds involving various functional groups. Anaerobic reduction of Fe(III) to Fe(II) by hydrazine resulted in weaker binding and the formation of smaller, less stable protein–humic acid complexes. These findings suggested that modulating Fe complexation under alternating aerobic and anaerobic conditions, such as those found in redox-cycling wastewater treatment, can be a promising strategy to enhance protein degradation.

The presence of ibuprofen (IBP) and paracetamol (PAR) contaminants in wastewater has become an emerging issue. Traditional wastewater treatment facilities have not been adequately upgraded to remove these micropollutants. This study focused on screening and identifying effective rhizobacteria capable of assisting plants in eliminating ibuprofen and paracetamol from wastewater using constructed wetlands. A total of 28 rhizobacteria were isolated from both the roots and the surrounding sand of Scirpus grossus after 30 days of pharmaceutical exposure. Among these, three isolates (Gram-negative Enterobacter aerogenes, Gram-positive Bacillus flexus, and Paenibacillus alvei) showed high tolerance to IBP and PAR with initial removal efficiencies > 75%. The addition of these three isolated rhizobacteria to a constructed wetland (planted with Scirpus grossus, 5-day HRT, 2 L/min aeration) assists the removal of IBP and PAR from wastewater. Bioaugmentation of rhizobacteria showed an increment of IBP removal (↑13%) from water (residual of 10 µg/L) and PAR (↑20%) from sand (residual 2.3 µg/L) as compared to the non-bioaugmented systems. The addition of rhizobacteria also showed the ability to significantly enhance the translocation of PAR into the shoot system of S. grossus, suggesting assisted phytoextraction mechanisms, while the removal of IBP in wetlands is suggested to occur via rhizodegradation. It is recommended that future research be conducted to elucidate the microbial degradation pathways and analyze the intermediate metabolites to accurately depict the pharmaceutical degradation mechanisms and evaluate their ecological risks.

Domestic wastewater discharge is the major source of pollution in Malaysia. Phytoremediation under hydroponic conditions was initiated to treat domestic wastewater and, at the same time, to resolve the space limitation issue by installing a hydroponic system in vertical space at the site. Water hyacinth (WH) was selected in this study to identify its performance of water hyacinth in removing nutrients in raw sewage under batch operation. In the batch experiment, the ratio of COD _initial/plant _initial was identified, and SPSS ANOVA analysis shows that the number of plant size factors was not statistically different in this study. Therefore, four WH, each with an initial weight of 60 ± 20 g, were recommended for this study. Throughout the 10 days of the batch experiment, the average of COD, BOD, TSS, TP, NH4, and color removal was 73%, 73%, 86%, 79%, 77%, and 54%, respectively. The WH biomass weight increased by an average of 78%. The plants have also improved the DO level from 0.24 mg/L to 4.88 mg/L. However, the pH of effluent decreased from pH 7.05 to pH 4.88 below the sewage Standard B discharge limit of pH 9–pH 5.50. Four WH plant groups were recommended for future study, as the COD removal among the other plant groups is not a statistically significant difference (p < 0.05). Furthermore, the lower plant biomass is preferable for the high pollutant removal performance due to the fact that it can reduce the maintenance and operating costs.

Aquaculture wastewater treatment not only assists in alleviating the scarcity of clean water for daily usage and environmental pollution, but also generates valuable byproducts. This paper aims to review the generation of wastewater from the aquaculture sector, its characteristics, and available treatment technologies, while comprehensively discussing the adoption of a biocircular economy approach through waste valorization. With rich nutrients, such as nitrogenous compounds, and the presence of phosphorus in the aquaculture effluent, these aspects could be explored and valorized into biofertilizers, broadening their application in aquaponics and hydroponics, as well as in algae and daphnid cultivation. Biofertilizer can also be used in agriculture because it contains essential elements needed by plants. Thus, methods of converting nutrients into biofertilizers in terms of sludge recovery can be accomplished via anaerobic and aerobic digestion, drying, composting, and vermicomposting. Moving forward, aquaculture effluent recovery is addressed under the biocircular economy by re-engaging aquaculture wastewater effluents into the production cycle. The enhancement of aquaculture effluents and biomass for uses such as aquaponics, hydroponics, algae cultivation, daphnid co-cultivation, and biofertilizers presents valuable opportunities for nutrient recovery while ensuring that non-toxic wastewater can be safely discharged into external water bodies. This approach has the potential to revolutionize wastewater treatment in aquaculture, shifting the economic model of wastewater management from a linear system to a circular, more sustainable one.

Aquaculture wastewater contains high levels of organic matter and nutrients, which can be harmful to aquatic life if discharged improperly into surface water bodies. Coagulation-flocculation is currently the best practice for treating aquaculture effluent with biocoagulants, offering an alternative to metal-based coagulants. This study aims to investigate the potential of Tamarindus indica seeds as a biocoagulant for treating aquaculture wastewater, focusing on the optimal solvent extraction, concentration, and dose. This study also examines the toxicity of biocoagulants to aquatic organisms. Coagulation-flocculation study was conducted under jar test experiment with NaCl, NaOH, and HCl used as solvents; concentration of 0-10 g/L; and doses of 1-5 % v/v under 120 rpm (rotation per minute) rapid mixing for 1 min, 20 rpm slow mixing for 20 mins, and 60 mins sedimentation time. A characterization study showed that NaCl-treated T. indica has a positive zeta potential charge, attributed to the presence of hydroxyl, carbonyl, and amide functional groups. Under this optimum condition (NaCl-extract, 6 g/L, and 4 % v/v), the biocoagulant achieved high removal (>50 %) of turbidity, TSS (total suspended solid), and ammonia and considerably good removal of other parameters (TN [total nitrogen], BOD5 [biological oxygen demand], COD [chemical oxygen demand]). The toxicity test revealed that no mortality was observed at a concentration of 1 g/L, whereas 10 g/L resulted in a 100 % mortality rate after 24 hours of exposure. Further toxicity analysis is suggested to be conducted using treated final effluent (not directly using biocoagulant substances) to observe the direct impact of the treated wastewater if discharged into the water bodies.

Increasing aquaculture cultivation produces large quantities of wastewater. If not handled properly, it can have negative impacts on the environment. Constructed wetlands (CWs) are one of the phytoremediation methods that can be applied to treat aquaculture effluent. This research was aimed at determining the performance of Cyperus rotundus in removing COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate from the batch CW system. Treatment was carried out for 30 days with variations in the number of plants (10, 15, and 20) and variations in media height (10, 12, and 14 cm). The result showed that aquaculture effluent contains high levels of organic compounds and nutrients, and C. rotundus can grow and thrive in 100% of aquaculture effluent. Besides that, the use of C. rotundus in CWs with the effect of numbers of plants and media height showed performance of COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate with 70, 79, 90, 96, 64, 82, 92, and 48% of removal efficacy, respectively. There was no negative impact observed on C. rotundus growth after exposure to aquaculture effluent, as indicated by the increase in wet weight, dry weight, and growth rate when compared to the control. Thus, adding aquaculture effluent to CWs planted with C. rotundus supports the growth and development of plants while also performing phytoremediation.

In this study, biosorption potential of nine epiphytic bacteria isolated from the rhizosphere of Lepironia articulata and Scirpus grossus were assessed. Identification of the isolated epiphytic rhizobacteria using 16S rRNA analysis showed species belonging to the four genera of Bacillus, Enterobacter, Aeromonas, and Chromobacterium. Batch biosorption studies were carried out to assess the capacity of the isolated bacteria to act as Pb and Cu biosorbents. Different initial concentrations of the two heavy metals (50, 100, 200, 300, and 400 ppm) were used to determine the ability of the biosorbent to reach a tolerance level and then calculate the percentage of biosorption with respect to 0.1 g dry weight. Initial concentration of Pb and Cu exposed showed that the isolated bacteria have high tolerance up to 400 ppm. Bacteria prefer Pb ions over Cu, which is indicated by higher removal of Pb in all tested reactors. Bacillus sp. (coded Sc1) showed the highest biosorption capacity with 100% Pb and 97% Cu removal.

Tofu effluent contains a high concentration of organic materials, nutrients, suspended solids and is also low in pH. This research was aimed at applying phytotreatment using floating plant species of Pistia stratiotes to polish tofu effluent before final discharge into water bodies while also producing biogas from the resultant biomass after treatment. A range-finding test (RFT) was conducted to determine the initial concentration to be treated and resulted in 10 % tofu effluent. Phytotreatment was conducted for a period of 14 days, focusing on the removal of organic matter and nutrient contents. After 14 days of treatment, P. stratiotes were able to remove total suspended solids (TSS) by 88 %, ammonia by 42.3 %, phosphate by 50 %, chemical oxygen demand (COD) by 84 %, and biological oxygen demand (BOD) by 95 %, significantly higher as compared to control. Phytotreatment was able to stabilize pH to a neutral value, and P. stratiotes were able to transfer oxygen from air to the rhizosphere area. The maximum daily production of biogas using the plant's biomass was higher as compared to the control; however, the overall biogas accumulation was significantly lower during the 45 days of observation. Further biomass pretreatment was suggested before digestion to obtain higher biogas production since the cellulose, hemicellulose, and lignin content inside the plant biomass were subjected to being hardly degraded by the anaerobic microorganisms.