Nutrient Removal Efficiency Research Articles

Optimizing photoperiods for enhanced microalgae-based phycoremediation of food wastewater in Malaysia

Food processing wastewater poses significant environmental challenges due to high pollutant levels, necessitating effective treatment methods. While Chlorella vulgaris has shown promise in wastewater treatment, the optimal light/dark photoperiod regimes for maximizing biomass growth, nutrient removal efficiency, and COD reduction remain underexplored. This study evaluates the effects of 12H:12H light/dark and 24H light photoperiods on the performance of C.vulgaris in treating food processing wastewater. The 12H:12H photoperiod achieved 73% COD removal with a biomass yield of 0.44 g/L, while the 24H light achieved 75% COD removal with a biomass yield of 1.02 g/L. Both photoperiods fully removed ammonia by day 12. Although the 24H light period increased biomass production, it is energy-intensive, whereas the 12H:12H photoperiod is more energy-efficient but requires further evaluation. These findings highlight the importance of optimizing photoperiod regimes to enhance the efficacy of microalgae-based wastewater treatment. This research supports sustainable wastewater management in the food industry and aims to meet regulatory standards through tailored photoperiod strategies.

EFFECT OF LOCALLY ISOLATED <i>SCENEDESMUS</i> SP. TN1 ON BIOMASS PRODUCTION AND NUTRIENT REMOVAL FROM COOKING COCOON WASTEWATER: EFFECTS OF INITIAL ALGAL CELL DENSITY AND TEMPERATURE

Scenedesmus sp. TN1, a local freshwater microalga, was cultivated in cooking cocoon wastewater. The effects of initial algal cell density and temperature on microalgae growth and the removal of total nitrogen (T-N), total phosphorus (T-P), and chemical oxygen demand (COD) were studied. The initial algal cell densities were 5, 10, 15, and 20 mg/l. The experimental temperatures varied from 20 °C to 30 °C. The growth rate increased with the increase in initial algal cell density up to 15 mg/l and was statistically stable thereafter. A similar trend of total nitrogen, total phosphorus, and COD removal efficiency was observed. The optimum temperature for microalgae growth and nutrient removal was 30 °C. After 9 days of cultivation, Scenedesmus sp. TN1 exhibited nutrient removal efficiencies of 88.28%, 82.91%, 92.01%, and 89.16% for T-N, T-P, biological oxygen demand (BOD5), and COD, respectively. The maximum biomass production and nutrient removal efficiencies of Scenedesmus sp. TN1 were observed at cultivation conditions of 15 mg/l initial algal cell density at 30 °C. This study compiled information on the cultivation conditions for cooking cocoon wastewater treatment practices.

Treatment of Swine Wastewater Using the Domestic Microalga Halochlorella rubescens KNUA214 for Bioenergy Production and Carotenoid Extraction

The management of swine wastewater (SW) presents significant environmental challenges, requiring solutions that combine effective treatment with resource recovery. This study highlights the dual role of microalgae in wastewater remediation and bioenergy production. H. rubescens KNUA214 was cultivated in media containing varying concentrations of diluted swine wastewater (DSW; 0%, 25%, 50%, and 100%). Cultivating with Blue Green-11 (BG-11) medium + 50% DSW maximized biomass growth, the chlorophyll content, and carotenoid production. Nutrient removal efficiency in 100% DSW over 8 days demonstrated reductions of 59.3% in total nitrogen, 67.7% in ammonia nitrogen, and 40.7% in total phosphorus, confirming the species’ capacity for effective wastewater treatment. The carotenoid analysis using HPLC revealed that astaxanthin, lutein, canthaxanthin, and beta-carotene exhibited the highest levels in BG-11 + 50% DSW. Furthermore, the biomass analyses confirmed its potential for bioenergy applications, with high calorific values and significant polyunsaturated fatty acid concentrations, enhancing its utility for bioenergy and biolubricant production. These findings position H. rubescens KNUA214 as an effective resource for integrating SW management with the sustainable production of high-value biochemicals, offering environmental and economic benefits.

Potential of culturing microalgae Chlorella vulgaris and Nannochloropsis oculata with aquaculture wastewater for simultaneous aquafeed production and wastewater remediation

Aquaculture expansion has resulted in nutrient pollution in aquatic ecosystems, primarily due to nitrogen-rich effluents, leading to eutrophication and degraded water quality. Although conventional wastewater treatment methods are effective, they are often costly and environmentally risky. Microalgae offer a promising alternative, enabling both wastewater remediation and the production of nutrient-rich biomass. However, most research has mainly focused on nutrient removal efficiencies, with relatively little attention given to the quality of the microalgal biomass and its suitability for simultaneous aquafeed production. This study evaluates the growth, nutritional content, and nutrient removal efficiencies of Chlorella vulgaris (C. vulgaris) and Nannochloropsis oculata (N. oculata) in synthetic aquaculture wastewater (AW). The findings reveal that both species showed significant growth in AW and F/2 media, with N. oculata reaching the highest cell density (17.6 × 10⁶ cells/mL) in AW. After seven days, C. vulgaris removed 83.7 ± 0.42% of nutrients in AW and 78.0 ± 4.35% in F/2, while N. oculata achieved 71.3 ± 1.50% and 72.3 ± 10.0%, respectively. Biomass from both species was also rich in protein (35.9–57.4%) and carbohydrates (12.7–40.9%). Particularly, N. oculata produced 46% dw protein and 40.9% dw carbohydrates in aquaculture wastewater, with protein levels higher than most previously reported values in such conditions. Additionally, with over 71% nutrient removal in only seven days, a longer culture duration and higher initial biomass inoculum could further enhance the efficiency. These findings highlight the potential of N. oculata and C. vulgaris for sustainable aquaculture, effectively treating aquaculture wastewater and producing high-quality aquafeed biomass, thereby supporting environmentally friendly and cost-effective practices.

Characterizing A21: Natural Cyanobacteria-Based Consortium with Potential for Steroid Bioremediation in Wastewater Treatment.

Microalga-bacteria consortia are increasingly recognized for their effectiveness in wastewater treatment, leveraging the metabolic synergy between microalgae and bacteria to enhance nutrient removal and overall treatment efficiency. These systems offer a sustainable approach to addressing pollutants such as nitrogen and phosphorus. However, their potential in removing specific contaminants like steroid hormones is less explored. In this study, a natural microbial consortium, A21, has been characterized and isolated from primary sewage treatment in Madrid and its potential for bioremediation of steroid hormone effluents has been evaluated. The A21 consortium includes Alphaproteobacteria genera Sphingopyxis and Pseudorhizobium and the Cyanobacterium Cyanobium. Sphingopyxis (31.78%) is known for biodegradation, while Pseudorhizobium (15.68%) exhibits detoxification abilities. Cyanobium (14.2%) may contribute to nutrient uptake and oxygen production. The effects of pH, nitrogen sources, and Sodium chloride concentrations on growth were evaluated. The optimal growth conditions were determined to be a pH range of 7 to 9, a salt concentration below 0.1 M, and the presence of a nitrogen source. The consortium also demonstrated effective growth across various types of wastewaters (primary, secondary, and tertiary treatment effluents). Additionally, A21 exhibited the ability to grow in the presence of steroids and transform them into other compounds, such as converting androstenedione (AD) into androsta-1,4-diene-3,17-dione (ADD) and β-estradiol into estrone.

Predicting organic matter and nutrient removal efficiency in a constructed wetland using data mining

Vertical and horizontal flow constructed wetlands (VF and HF CWs) are most widely used in the treatment of domestic sewage, storm runoff and selected industrial wastewaters. Current research focuses on the search for new applications, alternative substrates and developing mathematical and statistical methods to model the process of removing pollutants in CWs. This is important from a scientific and practical point of view. The performance of VF CWs with two types of substrate (gravel and Certyd - a waste material) was investigated over a two-year period. The following parameters were analyzed: biological oxygen demand (BOD5), chemical oxygen demand (COD), ammonia nitrogen (N-NH4), total nitrogen (N-Total), total phosphorus (P-Total) and dissolved oxygen (DO). At the same time, both the temperature of the inlet sewage and the air temperature were monitored. A support vector machine with a Gaussian kernel function was used to model the treatment efficiency. To select the model parameters, a 10-fold cross-validation was applied. The models applied were characterized by a very good fit. The expected average efficiency of organic removal was 88.3% (BOD5) and 80.8% (COD) in the bed filled with Certyd, and 83.8% (BOD5) and 76.9% (COD) in the bed with a classic filling. The predicted average efficiency of N-NH4 and N-Total removal in CWs filled with Certyd and gravel were 80.4 and 74.2%, and 59.6% and 57.0% respectively.

Assessment of temperature dynamics and microbial community responses in aerobic membrane bioreactors from mesophilic to hyper-thermophilic conditions.

This study investigates the impact of temperature variations on the performance of an aerobic membrane bioreactor (MBR) as it transitions from mesophilic (30°C) to hyper-thermophilic (65°C) conditions. The microbial community structure was analyzed using 16S rRNA gene sequencing to assess how temperature influences microbial diversity and composition. In mesophilic conditions, the system exhibited high alpha diversity with a Shannon index of 5.92 and 224 observed species. As the temperature increased to 45°C and 65°C, diversity decreased significantly, with Shannon indices of 2.54 and 2.82, and 96 and 77 observed species, respectively. Additionally, nutrient removal efficiency, particularly for ammonia and phosphorus, declined at higher temperatures. COD removal efficiency reached 96.5% at 30°C but decreased to 57% at 45°C before recovering to 94% at 65°C. Notably, biomass yield at hyper-thermophilic conditions was 37% lower than at mesophilic conditions, with a yield of 0.06 gVSS/gCODremoved. These findings highlight the potential advantages of operating under hyper-thermophilic conditions, including reduced sludge production, lower nutrient requirements, and increased organic loading capacity. The results provide valuable insights into optimizing high-temperature wastewater treatment processes for more efficient and sustainable industrial applications.

How Well Do Endemic Wetland Plant Species Perform in Water Purification?

Rising anthropogenic-induced nutrient enrichment of surface waters is of great concern globally as it jeopardizes the ecological integrity and functioning of freshwater ecosystems. Floating wetlands have been successfully used to treat nutrient enriched wastewater in developing nations, and provide additional co-benefits. We aimed to quantify the nutrient removal efficiency of high-potential, endemic wetland species on floating wetlands in different conditions and to understand whether the nutrient uptake process was characterised by key plant functional traits. Two experiments were run under Mediterranean-climate conditions of the Western Cape of South Africa: (1) a closed, oligotrophic mesocosm experiment representing local conditions and (2) a real-life (in-situ) eutrophic application. The mesocosm experiment conducted under oligotrophic local conditions yielded low nitrate, phosphate and ammonium removal rates (34.8–35.2 mgNO3-Nm− 2.d− 1, 10.4–10.7 mgPO4-Pm− 2.d− 1 and 3.6–3.8 mgNH4-Nm−2.d− 1) in comparison to other floating wetland studies globally, yet high removal efficiencies (> 90%). However the eutrophic in-situ experiment demonstrated the potential for these same endemic plants to remove up to 312 g.m− 2 of nitrogen and 47 g.m− 2 of phosphorus per year– which is relatively high compared to similar global research. Cyperus textilis had the highest daily nutrient uptake and content followed by Prionium serratum and Juncus lomatophyllus, while J. lomatophyllus had the greatest nutrient uptake efficiency. Two of the three species (C. textilis and P. serratum) stored significantly more total nutrients in their shoot tissue compared to their root tissue, suggesting that the permanent removal of nutrients from the system is possible through shoot harvesting. Floating wetlands planted with endemic plant species have the potential to remove nutrients effectively and sustainably from eutrophic water and can thus be implemented as low-cost nature-based solutions to mitigate pollution of lentic systems.

Comparative Study of Ammonium and Orthophosphate Removal Efficiency with Natural and Modified Clay-Based Materials, for Sustainable Management of Eutrophic Water Bodies

Eutrophication, a global threat that leads to degradation of freshwater and seawater aquatic ecosystems, is driven by excessive nutrient loading. This study explores the sustainable management of eutrophic water bodies with the application of natural and modified clay-based materials as a practical solution to mitigate eutrophication by removing ammonium and orthophosphate ions. Comparative analyses of six materials: natural zeolite, bentonite, and perlite, along with their modification with calcium and iron, were assessed after kinetic analysis of each material. Batch adsorption experiments were performed to evaluate the material’s performance in fresh and seawater. Fitting experimental data assessed adsorption kinetics to pseudo-second-order models. Furthermore, Langmuir isotherm models were employed to determine each material’s maximum adsorption capacity for ammonium and orthophosphate ion uptake. The results revealed that freshwater applications of modified zeolite or natural bentonite achieved better orthophosphate ion removal efficiency from seawater, whereas employing natural zeolite maximized the ammonium ion removal efficiency in freshwater bodies. Finally, orthophosphate and ammonium ion removal efficiency results for almost all materials were diminished in seawater. This research contributes valuable insights to the development of efficient and sustainable nutrient removal methodologies to remediate natural eutrophic water bodies and protect aquatic ecosystems.

Sustainable land-based IMTA: Holistic management of finfish, mussel, and macroalgae interactions, emphasizing water quality and nutrient dynamics

This research aims to minimize the environmental impact and promote the sustainability of aquaculture by optimizing nutrient dynamics, improving water quality and enhancing species growth performance through a land-based Integrated Multi-Trophic Aquaculture (IMTA) system. The study focused on Black Sea trout (Salmo labrax), Mediterranean mussel (Mytilus galloprovincialis), and sea lettuce (Ulva lactuca), reared in interconnected tanks using Black Sea water over 90 days. The Black Sea trout more than doubled in size to 333.92 ± 6.60 g and significant improvements were observed in the specific growth rate (SGR) at 0.85% and the feed conversion ratio (FCR) at 1.38. The fish's proximate composition included 19.19% protein, 2.31% lipid, 70.35% moisture, and 1.34% ash, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels at 6.06% and 13.50%, respectively. The macroalgae showed substantial growth, with a SGR of 0.34% and a weight gain of 310 ± 3.50 g. Additionally, it increased protein content by 13.41% and demonstrated significant nutrient removal efficiencies: 41.4% for nitrate, 66.7% for nitrite, and 90.8% for ammonia. EPA and DHA levels increased by 45% and 70%, reaching 4.66% and 2.19%, respectively. In contrast, the mussels experienced a weight loss, with a weight gain of −1.20 ± 0.00 g and an SGR of −0.20%. Initially, wild mussels had a composition of 77.56% moisture, 13.79% protein, 1.54% lipid, and 1.77% ash. The presence of mussels and macroalgae significantly improved water quality, notably reducing ammonia by 92.2%, nitrate by 44.6% and nitrite by 75%, benefiting the overall ecosystem. This study concludes that a land-based IMTA system enhances sustainable aquaculture by improving product quality and bioremediation, with macroalgae playing a crucial role in nutrient absorption and growth within the system.

Synergistic microalgal co-cultivation for treatment of municipal wastewater using a two-stage cultivation system and biomass valorization

The present study aimed to develop different microalgal co-cultivation Tetraselmis indica BDUG001 (TS) and Picochlorum sp. (PC) for the treatment and recycling of raw municipal wastewater (MWW). The nutrient removal and biomolecules production, 75 % raw MWW + 25 % ASN-III, 50 % secondary treated municipal wastewater (STMWW) + 50 % ASN-III, and 50 % TS-treated MWW (TSTMWW) + 50 % ASN-III was used. Among them, co-cultivation 2TS:1PC and 2PC:1TS exhibited maximum nutrient removal efficiency (NRE) and biomass and biomolecules production in 75 % raw MWW + 25 % ASN-III, and 50 % TSTMWW + 50 % ASN-III, respectively. Based on the above outcomes, two-stage cultivation systems (TSCSs) were developed to maximize the NRE and biomolecules production using the micro vertical glass photobioreactor (MVG-PBR). 2TS:1PC and 2PC:1TS co-cultivation ratio was used for first and second stage of cultivation and noted as 2TS:1PC (S1) and 2PC:TS (S2), respectively. The co-cultivation ratios were compared with monoculture TS (S1) and PC (S2), and the cost analysis was performed to assess the viability of the process. The obtained results showed that during the first stage of TSCSs, co-cultivation 2TS:1PC (S1) and TS (S1) exhibited NRE of COD (95 and 91.42 %), TN (93.06 and 89.54 %) and TP (100 and 93.87 %), and generated dry biomass (3.11 and 2.75 g/L), lipid content (46 and 42.17 %) having FAME content (82.25 and 32.01 %), astaxanthin (1.12 and 0.93 mg/g DCW) and β-carotene (7.01 and 3.30 mg/g DCW), respectively. During the second stage of TSCSs, co-cultivation 2PC:1TS (S2) and PC (S2) exhibited NRE of COD (95.50 and 93.28 %), TN (98.97 and 94.38 %) and TP (100 and 94.50 %), and generated biomass (3.24 and 2.78 g/L), lipid content (48.50 and 40.70 %) having FAME content (86.78 and 44.20 %), astaxanthin (1.15 and 0.71 mg/g DCW) and β-carotene (5.14 and 5.33 mg/g DCW), respectively. The cost analysis suggested that co-cultivation-assisted TSSCSs generated more revenue compared to monoculture-based TSCSs.

Combining fermentation broth with spent water recycling for microalgae cultivation: Nutrient reutilization, biodiesel production and techno-economic simulation

This study presents an innovative and promising technology, Water Cycling Combined Fermentation Broth (WC2FB), which offers a sustainable solution to significantly reduce the costs associated with microalgae-based biodiesel production. The innovative approach involves utilizing food waste as a nutrient source, supplemented by recycled water after microalgae harvesting, with the goal of improving the viability of industrial biofuel production. The results of nutrient removal efficiency demonstrated that the addition of 15% fermentation broth to the microalgal suspension efficiently utilized volatile fatty acids, resulting in a significant increase in lipid content. Additionally, biocomponent analysis confirmed that the WC2FB mode did not compromise the desirable properties of biodiesel. Through techno-economic simulations, we predicted a 90% probability of achieving net present value (NPV) at a selling price of $5/kg. Finally, we recommended that directing future efforts be directly towards the development of culture devices, low-cost bioflocculation methods, and biorefinery extraction to further advance biodiesel production.

Biomass Accumulation, Contaminant Removal, and Settling Performance of Chlorella sp. in Unsterilized and Diluted Anaerobic Digestion Effluent

Microalgae demonstrate significant efficacy in wastewater treatment. Anaerobic digestion effluent (ADE) is regarded as an underutilized resource, abundant in carbon, nitrogen, phosphorus, and other nutrients; however, the presence of inhibitory factors restricts microalgal growth, thereby preventing its direct treatment via microalgae. The purpose of this study was to dilute ADE using various dilution media and subsequently cultivate Chlorella sp. to identify optimal culture conditions that enhance microalgal biomass and water quality. The effects of various dilution conditions were assessed by evaluating the biomass, sedimentation properties, and nutrient removal efficiencies of microalgae. The results demonstrate that microalgal biomass increases as the dilution ratio increased. The microalgae biomass in the treatments diluted with simulated wastewater was significantly higher than that with deionized water, but their effluent quality failed to meet discharge standards. The treatment diluted with deionized water for 10 times exhibited abundant microbial biomass with strong antioxidant properties. The corresponding total phosphorus concentration in the effluent (6.96 mg/L) adhered to emission limits under the Livestock and Poultry Industry Pollutant Emission Standards (8 mg/L), while ammonia nitrogen concentration (90 mg/L) was near compliance (80 mg/L). The corresponding microbial biomass, with a sludge volume index (SVI30) of 72.72 mL/g, can be recovered economically and efficiently by simple precipitation. Its high protein (52.07%) and carbohydrate (27.05%) content, coupled with low ash (10.75%), makes it a promising candidate for animal feed and fermentation. This study will aid in understanding microalgal growth in unsterilized ADE and establish a theoretical foundation for cost-effective ADE purification and microalgal biomass production.

Electrochemical Methods for Nutrient Removal in Wastewater: A Review of Advanced Electrode Materials, Processes, and Applications

In response to the increasing global water demand and the pressing environmental challenges posed by climate change, the development of advanced wastewater treatment processes has become essential. This study introduces novel electrochemical technologies and examines the scalability of industrial-scale electrooxidation (EO) methods for wastewater treatment, focusing on simplifying processes and reducing operational costs. Focusing on the effective removal of key nutrients, specifically nitrogen and phosphorus, from wastewater, this review highlights recent advancements in electrode materials and innovative designs, such as high-performance metal oxides and carbon-based electrodes, that enhance efficiency and sustainability. Additionally, a comprehensive discussion covers a range of electrochemical methods, including electrocoagulation and electrooxidation, each evaluated for their effectiveness in nutrient removal. Unlike previous studies, this review not only examines nutrient removal efficiency, but also assesses the industrial applicability of these technologies through case studies, demonstrating their potential in municipal and industrial wastewater contexts. By advancing durable and cost-effective electrode materials, this study emphasizes the potential of electrochemical wastewater treatment technologies to address global water quality issues and promote environmental sustainability. Future research directions are identified with a focus on overcoming current limitations, such as high operational costs and electrode degradation, and positioning electrochemical treatment as a promising solution for sustainable water resource management on a larger scale.

Prioritizing conservation sites for multi-pond systems to maintain protection of water quality in a fragmented agricultural catchment

Precise targeting of conservation practices to the most effective sites in multi-pond systems (MPSs) is critical for resource optimization and water quality improvement. Previous studies generally prioritized ponds for conservation practices considering nutrient removal efficiency. However, they have frequently overlooked the role of ponds in sediment interception and the impact of human activities and environmental factors around the pond. Herein, the present study developed and applied a novel framework for pond prioritization by integrating the Pressure-State-Response (PSR) model, graph theory, and K-mean clustering. The framework consists of three components. An indicator system is developed to represent the nutrient removal performance of any MPS, impacts on catchment sediment connectivity, external threats, and human-initiated conservation. A flow path network considering natural and artificial elements was constructed to calculate indicator values. A cluster analysis was conducted on the index values of different ponds, and a hierarchical sorting method were used to prioritize ponds. The framework was applied to the Guilinqiao Catchment, a typical fragmented agricultural catchment in the Yangtze River Basin, China. The study has quantified the Pressure, State, and Response indices of different ponds in this catchment, prioritized the ponds, and drawn recommendations for conserving MPSs based on field surveys and remote sensing data. Ponds with higher Pressure index, higher State index, and lower Response index scores should be targeted as conservation priorities. This framework provides an effective method for ensuring management of MPSs to sustainably maximize water cleanup capacity with limited resources.

Sustainable remediation of piggery wastewater using a novel mixotrophic Chlorella sorokiniana Cbeo for high value biomass production

Piggery wastewater (PW) contains high density of organic carbon (COD), nitrogen (NH4+-N and TN) and phosphorous (TP), which are essential nutrients for microalgae growth. This work was attempted to use a newly isolate Chlorella sorokiniana Cbeo for recovery these compounds into its biomass via mixotrophic cultivation. Critical factors including level of ammonia, C/N ratio, pH, light intensity, sterilized/unsterilized media, and indoor/outdoor cultivations affecting biomass production and nutrients removal efficiencies were investigated. Data revealed that C. sorokiniana Cbeo achieved the optimal growth in the unsterilized medium at NH4+-N concentration, C/N ratio, initial pH, and light intensity of 250 mg/L, 10/1, 7, and 150 μmol/m2/s, respectively. Under the optimal conditions, dry cell weight (DCW) reached the maximal level of 4.30 g/L, which was slightly higher than 4.14 g/L determined for the sterilized medium. In 30 L-scale photobioreactor, C. sorokiniana Cbeo grown under indoor and outdoor achieved DCW of 3.61 and 3.19 g/L, respectively. COD, NH4+-N, TN, TP removal efficiencies for both conditions were determined as 91.9–96.7, 96.6–99.7, 96.2–96.4, and 98.2–100 %, respectively. The C. sorokiniana Cbeo biomass contained 14–27 % lipid, 25–32 % carbohydrate, 44–48 % protein, and 0.25–0.97 % lutein. Interestingly, α-Linolenic acid (C18:3n3) was 19.84 –27.0 % of the total fatty acids. C. sorokiniana Cbeo is the promising algal strain for development of a sustainable biorefinery of PW.

Transforming wastewater-derived algae biodiesel with ammonium hydroxide emulsion for enhanced energy efficiency and emission reduction

The growing demand for sustainable energy has prompted a search for alternative fuels, with microalgae-based biodiesel emerging as a promising option. However, improving its energy efficiency and minimizing environmental impacts remain key challenges. This study presents a novel approach by integrating wastewater-derived algae cultivation with ammonium hydroxide emulsion to enhance biodiesel performance. Chlorella vulgaris microalgae were grown in a medium of diluted human urine, where nutrient removal efficiency was evaluated, and biooil was extracted via solvent extraction. The resulting biodiesel was analyzed for elemental, chemical, and physicochemical properties. A 30 % blend of Chlorella vulgaris algae biodiesel (CVAB) with normal diesel fuel (NDF) was prepared. To further boost energy efficiency and emissions performance, ammonium hydroxide emulsion was added at concentrations of 5 % and 10 %. Results confirmed that wastewater-sourced algae cultivation is a viable method for sustainable biodiesel production. While CVAB's combustion characteristics were similar to NDF's, it exhibited a 7 % decrease in brake thermal efficiency and a 5 % increase in nitrogen oxide emissions. The addition of ammonium hydroxide emulsion notably improved both energy efficiency and emission profiles. This study highlights a breakthrough in using ammonium hydroxide emulsion to enhance algae biodiesel, making it a more competitive alternative to fossil fuels. Economically, this approach offers a dual advantage: utilizing low-cost wastewater for biodiesel production while improving fuel performance and reducing emissions.

Effects of Temperature and Light on Microalgal Growth and Nutrient Removal in Turtle Aquaculture Wastewater.

The aim of this study was to explore the effects of temperature and light on microalgal growth and nutrient removal in turtle aquaculture wastewater using a single-factor experiment method. Results showed that the growth process of Desmodesmus sp. CHX1 in turtle aquaculture wastewater exhibited three stages, namely adaptation, logarithmic, and stable periods. Temperature and light significantly influenced the growth and protein and lipid accumulation of Desmodesmus sp. CHX1. The optimal conditions for the growth and biomass accumulation of Desmodesmus sp. CHX1 included a temperature of 30 °C, a photoperiod of 24L:0D, and a light intensity of 180 μmol photon/(m2·s). Increased temperature, photoperiod, and light intensity enhanced nutrient removal efficiency. Maximum nitrogen removal was achieved at a temperature of 30 °C, a photoperiod of 24L:0D, and a light intensity of 180 μmol photon/(m2·s), with the removal efficiency of 86.53%, 97.94%, 99.57%, and 99.15% for ammonia, nitrate, nitrite, and total phosphorus (TP), respectively. Temperature did not significantly affect TP removal, but increased photoperiod and light intensity improved the removal efficiency of TP. The development of microalgae biomass as a feed rich in protein and lipids could address feed shortages and meet the nutritional needs of turtles, offering a feasible solution for large-scale production.

Interactions between SDBS and Hydrilla verticillata − epiphytic biofilm in wetland receiving STPs effluents: Nutrients removal and epiphytic microbial assembly

The fate and effects of sodium dodecyl benzene sulfonate (SDBS) in sewage treatment plants effluents on nutrients and submerged macrophytes are far from clear in wetlands. This study conducted a 24-day experiment to investigate changes in nutrients and epiphytic biofilm of Hydrilla verticillata in wetlands receiving effluents with 0.5, 2 and 5 mg L−1 SDBS. The decrease of SDBS in overlying water followed pseudo-first-order kinetic equation, with over 80 % of SDBS removal achieved. 2 and 5 mg L−1 SDBS decreased nutrient removal efficiency, induced oxidative stress response and damaged cells of H. verticillata. SDBS altered bacterial and eukaryotic community diversity. 0.5 mg L−1 SDBS can promote carbon fixation and methane oxidation of microorganisms. Network analysis revealed that 0.5 mg L−1 SDBS decreased the stability of epiphytic ecosystems. Mantel tests indicated significant influences of SDBS, temperature, and total nitrogen on epiphytic microbial communities.

Experimental evaluation of Scenedesmus javanensis, Halochlorella rubescens, and Chlorolobion braunii for lipid-rich biomass production and phycoremediation of dairy wastewater

Phycoremediation uses algae as an ecotechnological tool to recycle eutrophic and polluted wastewater from industries. It is vital for fostering a sustainable circular bioeconomy, as the resulting algal biomass can be utilized as a versatile industrial bioresource. This approach is especially pertinent for the dairy industry, which produces substantial amounts of nutrient-rich dairy wastewater (DWW). The effectiveness of phycoremediation of DWW depends on the knowledge of indigenous algae that can thrive in such conditions and rapidly produce lipid-rich or nutraceutically or otherwise valuable biomass. This study assessed the lab-scale phycoremediation of DWW, emphasizing the biomass production potential and quality of three fast-growing green microalgae: Chlorolobion braunii, Scenedesmus javanensis, and Halochlorella rubescens, which are recognized for their high lipid yield potential in growth media. We assessed nutrient and mineral removal efficiency, biomass yield, productivity, biomass quality, and the biodiesel properties of lipids from these algae after ten days of growth in various dilutions and 100 % DWW. C. braunii demonstrated the highest biomass productivity of 149.32 mg L−1 d−1 in 100 % DWW. All species significantly reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) of DWW, achieving complete removal of nutrients, along with 80–100 % removal of heavy metals after growth in DWW. C. braunii had a lipid productivity of 49.79 mg L−1 d−1 in 100 % DWW, and lipids from C. braunii and S. javanensis were suitable for biodiesel production, highlighting their potential for large-scale industrial phycoremediation of DWW while generating biodiesel-grade lipids and other valuable bioproducts.