Feasibility of using brewery wastewater for biodiesel production and nutrient removal by Scenedesmus dimorphus

Mixotrophic Cultivation of Arthrospira platensis (Spirulina) under Salt Stress: Effect on Biomass Composition, FAME Profile and Phycocyanin Content

Arthrospira platensis holds promise for biotechnological applications due to its rapid growth and ability to produce valuable bioactive compounds like phycocyanin (PC). This study explores the impact of salinity and brewery wastewater (BWW) on the mixotrophic cultivation of A. platensis. Utilizing BWW as an organic carbon source and seawater (SW) for salt stress, we aim to optimize PC production and biomass composition. Under mixotrophic conditions with 2% BWW and SW, A. platensis showed enhanced biomass productivity, reaching a maximum of 3.70 g L-1 and significant increases in PC concentration. This study also observed changes in biochemical composition, with elevated protein and carbohydrate levels under salt stress that mimics the use of seawater. Mixotrophic cultivation with BWW and SW also influenced the FAME profile, enhancing the content of C16:0 and C18:1 FAMES. The purity (EP of 1.15) and yield (100 mg g-1) of PC were notably higher in mixotrophic cultures, indicating the potential for commercial applications in food, cosmetics, and pharmaceuticals. This research underscores the benefits of integrating the use of saline water with waste valorization in microalgae cultivation, promoting sustainability and economic efficiency in biotechnological processes.

Biotreatment of Industrial Wastewater using Microalgae: A Tool for a Sustainable Bioeconomy

Fresh water is one of the essential sources of life, and its requirement has increased in the past years due to population growth and industrialization. Industries use huge quantities of fresh water for their processes, and generate high quantities of wastewater rich in organic matter, nitrates, and phosphates. These effluents have contaminated the freshwater sources and there is a need to recycle this wastewater in an ecologically harmless manner. Microalgae use the nutrients in the wastewater as a medium for growth and the biomass produced are rich in nutrition that can cater growing food and energy needs. The primary and secondary metabolites of microalgae are utilized as biofuel and as active ingredients in cosmetics, animal feed, therapeutics, and pharmaceutical products. In this review, we explore food processing industries like dairy, meat, aquaculture, breweries, and their wastewater for the microalgal growth. Current treatment methods are expensive and energy demanding, which indirectly leads to higher greenhouse gas emissions. Microalgae acts as a potential biotreatment tool and mitigates carbon dioxide due to their high photosynthetic efficiency. This review aims to address the need to recycle wastewater generated from such industries and potentiality to use microalgae for biotreatment. This will help to build a circular bioeconomy by using wastewater as a valuable resource to produce valuable products.

Enhancement of protein production using synthetic brewery wastewater by Haematococcus pluvialis

Microalgae is a sustainable protein source that has been widely applied in animal feeds, functional foods, pharmaceutical, and cosmeceutical industries. Waste products could be a potential cost-saving and nutrient-rich substrate in the cultivation of microalgae for protein production. This study aims to investigate the cultivation condition of Haematococcus pluvialis for protein synthesis using synthetic brewery wastewater (BW). H. pluvialis was cultivated in the Bold's Basal Medium (BBM) mixed with synthetic BW at different concentrations. Various cultivation conditions including brewer's spent grain hydrolysate (BSGH) concentrations, pH, and light sources were studied. The molecular weight, amino acids profile and antioxidant activity of synthesized protein were determined. Fed-batch cultivation using different percentages of fresh medium replacement for enhancing protein production was investigated. The 20% fed-batch cultivation reached 27 ×10⁵ ± 0.42 cells/mL, and 4-fold of the protein content of 64.93 ± 5.30% of dry weight was recorded on day-13. Seven essential amino acids (lysine, threonine, histidine, phenylalanine, isoleucine, leucine, methionine) were produced in fed-batch cultivation. Red LED obtained the highest DPPH radical scavenging activity of 27.47 ± 0.98%. The findings suggested that BW is a promising substrate in the cultivation of H. pluvialis to commercially produce protein for numerous industrial applications.

A comprehensive review on emerging trends in industrial wastewater research

Rapid industrialization is one of the intricate factors that is linked to the depletion of water resources and increased generation of wastewater. Due to various obstructions and impediments, such as ineffective treatment solutions, exorbitant prices, lack of basic amenities, insufficient financial assistance, and technical expertise, sustainable treatment of industrial effluents has become an onerous process in most parts of the world. The majority of current treatment solutions are conventional and outdated, and thus fall short to remove all the contaminants efficiently from the industrial wastewater. Moreover, poorly treated or untreated industrial effluents are indiscriminately dumped into water bodies such as lakes, ponds, and rivers, causing substantial health hazards to humans and animals and serious threats to the aquatic ecosystem. Thus, there is a need for highly efficient, cost-effective, and sustainable technologies for the treatment of industrial wastewater. Employment of microbial technologies such as microbial fuel cells and microalgal technologies, treatment of wastewater can be coupled with the production of bioelectricity and valuable biomass, respectively. Moreover, with nanofiltration and biochar technologies, the efficiency of the overall treatment procedure can be increased to a greater extent. The present review aims to highlight opportunities and challenges associated with some of the emerging trends in industrial wastewater research.

Potential Application of Algae in Biodegradation of Phenol: A Review and Bibliometric Study

One of the most severe environmental issues affecting the sustainable growth of human society is water pollution. Phenolic compounds are toxic, hazardous and carcinogenic to humans and animals even at low concentrations. Thus, it is compulsory to remove the compounds from polluted wastewater before being discharged into the ecosystem. Biotechnology has been coping with environmental problems using a broad spectrum of microorganisms and biocatalysts to establish innovative techniques for biodegradation. Biological treatment is preferable as it is cost-effective in removing organic pollutants, including phenol. The advantages and the enzymes involved in the metabolic degradation of phenol render the efficiency of microalgae in the degradation process. The focus of this review is to explore the trends in publication (within the year of 2000-2020) through bibliometric analysis and the mechanisms involved in algae phenol degradation. Current studies and publications on the use of algae in bioremediation have been observed to expand due to environmental problems and the versatility of microalgae. VOSviewer and SciMAT software were used in this review to further analyse the links and interaction of the selected keywords. It was noted that publication is advancing, with China, Spain and the United States dominating the studies with total publications of 36, 28 and 22, respectively. Hence, this review will provide an insight into the trends and potential use of algae in degradation.

Cultivating Scenedesmus dimorphus in lactic acid wastewater for cost-effective biodiesel production

The combination of lactic acid production wastewater and oil-producing microalgal culture could not only achieve harmless treatment of wastewater but also provided nutrients and significant amounts of water for microalgal culture. Thus the effects of different nutrients on the biomass yield, lipid yield of Scenedesmus dimorphus with lactic acid wastewater were investigated. Although lactic acid wastewater was very suitable for the cultivation of oil-producing microalgae, some nutrients were still needed. So 0.79 g/L NaNO₃, 14 mg/L MgSO₄·7H₂O, 4 mg/L K₂HPO₄·3H₂O, and trace elements needed to be added in the microalgal culture with lactic acid wastewater. In the optimized wastewater medium, the lipid yield could reach 1.54 ± 0.04 g/L, which was 48.1% higher than the level of 1.04 ± 0.06 g/L in the BG11 medium. Microalgae cells had high absorption capacity for nitrogen and phosphorus. The nitrogen, phosphorus removal rate of wastewater reached 96.31% and 90.78%, respectively, after 10 days of culture. And the treated wastewater could be used for lactic acid production for four times. These investigations laid a foundation for reducing the pollution of lactic acid wastewater, exploring a late-model for oleaginous microalgae cleaner production.

Influence of Nitrogen to Phosphorus Ratio and CO2 Concentration on Lipids Accumulation of Scenedesmus dimorphus for Bioenergy Production and CO2 Biofixation

The potential of Scenedesmus dimorphus microalgae for CO₂ biofixation and lipid biosynthesis for bioenergy applications was evaluated in this study. Batch experiments were conducted using synthetic tertiary municipal wastewater samples at several nitrogen to phosphorus (NP) ratios (1 : 1 to 8 : 1) and CO₂ concentrations (∼0%, 2%, 4%, and 6% CO₂ in supplied air). Scenedesmus dimorphus was cultivated for 25 days and the growth is highly dependent on the CO₂ concentration and the NP ratio. An NP ratio of 2 : 1 produces a biomass yield of 733 mg/L when the microalga culture was supplied with air enriched with 2% CO₂ . The maximum CO₂ biofixation rate of 49.6 mg L^-1  d^-1 is at an NP ratio of 8 : 1 with 4% CO₂ . A colorimetric technique depending on sulpho-phospho-vanillin (SPV) was utilized for the determination of the intracellular lipid content. The highest lipid content of 31.6% as the dry weight of the biomass is at an NP ratio of 1 : 1 and 6% CO₂ . These results indicate that supplementation of suitable CO₂ with favorable NP ratio has a considerable effect on lipid accumulation in the microalgae Scenedesmus dimorphus biomass.

Microalgae Brewery Wastewater Treatment: Potentials, Benefits and the Challenges

Concerns about environmental safety have led to strict regulations on the discharge of final brewery effluents into water bodies. Brewery wastewater contains huge amounts of organic compounds that can cause environmental pollution. The microalgae wastewater treatment method is an emerging environmentally friendly biotechnological process. Microalgae grow well in nutrient-rich wastewater by absorbing organic nutrients and converting them into useful biomass. The harvested biomass can be used as animal feed, as an alternative energy source for biodiesel production and as biofertilizer. This review discusses conventional and current brewery wastewater treatment methods, and the application and potential of microalgae in brewery wastewater treatment. This study also discusses the benefits as well as challenges associated with microalgae brewery and other industrial wastewater treatments.

Effect of different phosphorus concentrations on biodiesel production from Isochrysis zhangjiangensis under nitrogen sufficiency or deprivation condition

The effects of two nitrogen (N) concentrations combining with three phosphorus (P) concentrations on Isochrysis zhangjiangensis growth and formation of fatty acid (FA) were investigated in this study. Biomass concentration, mass fraction, and productivity of FA in I. zhangjiangensis were low in N-deprived media. Under both N and P sufficiency conditions, the intake of P and N was 40 times and 4.7 times of the normal algal growth condition, respectively, indicating I. zhangjiangensis had the potential for removing P and N from high concentrated N and P salinity wastewater. This study also showed that P deficiency in N sufficient medium increased the FA content, however, the difference between P limitation and P deprivation was not significant (P > 0.05). In N sufficient and P limitation medium, FA productivity was the highest, with a composition suitable for biofuel, so, this condition was the optimal condition for biodiesel production from I. zhangjiangensis.

Algal treatment of wastewater generated during oil and gas production using hydraulic fracturing technology

Hydraulic fracturing technology is widely used for recovering natural gas and oil from tight oil and gas reserves. Large volumes of wastewater, flowback water, are produced during the fracturing process. This study examines algal treatment of flowback water. Thirteen microalgae strains consisting of cyanobacteria and green algae were examined. Wastewater quality before and after algae treatment, as well as volatile matter, fixed carbon and ash contents of the biomass grown in flowback water were examined. The experimental results demonstrated that microalgae can grow in flowback water. The chemical composition of the algal biomass produced in flowback water was strain specific. Over 65% total dissolved solids, 100% nitrate and over 95% boron reduction in flowback water could be achieved. Hence, algal treatment of flowback water can significantly reduce the adverse environmental impact of hydraulic fracturing technology and produce biomass that can be converted to bioproducts.

Pretreatment of brewery effluent to cultivate Spirulina sp. for nutrients removal and biomass production

Due to the low concentration of nitrate and high contents of organics, brewery effluent was not suitable for the cultivation of Spirulina sp. This work changed the nutrient profile of brewery effluent effectively by dilution, addition of nitrate, and anaerobic digestion. The result showed that the optimum dilution rate and NaNO₃ addition for brewery effluent were 20% and 0.5 g/L, respectively. Spirulina sp. grown in pretreated brewery effluent produced 1.562 mg/L biomass and reduced concentrations of nutrients to reach the permissible dischargeable limits. In addition, Spirulina sp. grown in pretreated brewery effluent had much higher protein content and oil content. So the appropriate treatment converted brewery effluent into a nutrient balanced medium for algae cultivation and alleviated the potential environmental problems. Pretreatment procedure developed in this work is an effective way to realize the sustainable utilization of brewery effluent and produce algal biomass with valuable nutrients.

Polishing of anaerobic secondary effluent by Chlorella vulgaris under low light intensity

To investigate anaerobic secondary effluent polishing by microalgae (Chlorella vulgaris) under low light intensity (14μmol/m²/s), bubbling column reactors were operated in batches of 8 d with initial ammonium nitrogen 10-50mg/L, initial phosphate phosphorus 2-10mg/L and microalgal seed 40mg/L. Maximum microalgal biomass and minimum generation time were 370.9mg/L and 2.5d, respectively. Nitrogen removal (maximum 99.6%) was mainly attributed to microalgal growth rate, while phosphorus removal (maximum 49.8%) was related to microalgal growth rate, cell phosphorus content (maximum 1.5%) and initial nutrients ratio. Dissolved microalgal organics release in terms of chemical oxygen demand (maximum 63.2mg/L) and hexane extractable material (i.e., oil and grease, maximum 8.5mg/L) was firstly reported and mainly affected by nitrogen deficiency and deteriorated effluent quality. Ultrafiltration critical flux (16.6-39.5L/m²/h) showed negative linear correlation to microalgal biomass. Anaerobic membrane bioreactor effluent polishing showed similar results with slight inhibition to synthetic effluent.

An oleaginous filamentous microalgae Tribonema minus exhibits high removing potential of industrial phenol contaminants

Discharge of industrial phenol contaminants could cause great harm on natural environment. Through oleaginous microalgae cultivation in phenolic wastewater, pollutants can be phototrophically biofixed into biomass as feedstock for bioenergy production. It was firstly reported in this study that, an oleaginous filamentous microalgae Tribonema minus exhibited strong environmental phenol removal ability. T. minus filaments showed 449.46mgg^-1 of phenol-uptake capacity, obviously higher than those strains with low phenol absorption such as Scenedesmus dimorphus. And phenols could be removed efficiently at the initial phenol concentration up to 700mgL^-1. Simultaneously, through T. minus growth, phenol concentration could be decreased from 100mgL^-1 to the range of 0.1-0.5mgL^-1, which meet industrial discharge need of phenol contaminants in most countries. So Tribonema minus is a potential algal specie to help the construction of integrated process for both oleaginous biomass production and bioremediation of phenol contaminants.