Biological Treatment of Second Cheese Whey Using Marine Microalgae/Cyanobacteria-Based Systems

Batch kinetics of nutrients removal for palm oil mill effluent and recovery of lipid by Nannochloropsis sp

In the present study, recording and evaluation of the current practices applied for the treatment of wastewater and cheese whey, derived from ten cheese manufacturing units in Greece, was performed. Wastewater from cheese manufacturing includes milk losses, wastewater generated by the staff and by the washing of equipment, floors and milk transferring vehicles. Based on the study, cheese whey is separately collected from the cheese manufacturing wastewater in almost all the Greek units under study. Wastewater generated by Greek medium size units is mainly treated through the extended aeration activated sludge process, while wastewater derived from small size units is either disposed in the sewage system or it is stored until its transportation for further treatment. Moreover, aiming at revealing the potential exploitation opportunities, a comprehensive literature review on cheese whey valorisation technologies was also conducted. The literature review revealed that cheese whey and whey components can be used in a wide range of applications, mainly in the food and nutraceutical industry, as they contain several beneficial compounds that can be exploited. In this context, the increasing consumer concerns related to health and wellbeing have enhanced the acceptability and demand for whey products, such as the whey protein concentrates and isolates, the whey powder, the reduced lactose whey, etc. Moreover, cheese whey can be used for the production of sustainable energy alternatives to fossil fuels, such as ethanol, hydrogen and biogas. Among them, biogas production through anaerobic digestion could be a viable solution since relevant economic analysis revealed that this technology is a profitable and sustainable investment for a Greek cheese whey factory.

Microalgae biomass is regarded as a potential feedstock for valuable compounds such as pigments, lipids and proteins. However, development of single molecule extraction processes is the most common practice. A green multiproduct extraction approach is needed for economically sustainable process development of the microalgal industry. Therefore, this study aims to investigate the sequential extraction of lutein and lipid from dry and wet Chlorella pyrenoidosa biomass pretreated with a choline chloride-based deep eutectic solvent (DES) under a sustainable biorefinery scheme. In this context, we have assessed the kinetic modeling of the solid-liquid extraction process for the aforementioned compounds, focusing on the effects of temperature and time. The maximum lutein (3.80 mg g-1) and lipid (95.0 mg g-1) contents from dry biomass were obtained at 45 °C in 40 min and at 70 °C in 90 min, respectively. From wet biomass, the maximum lutein (2.57 mg g-1) and lipid contents (87.47 mg g-1) were obtained at 35 °C in 40 min and at 70 °C in 90 min, respectively. The kinetics of the solvent-based extraction process for lutein and lipids were assessed via first-order and second-order kinetic models with an associated investigation of kinetic parameters, such as rate constants, saturation concentration and activation energies. We found that temperature is an important parameter that influences the extraction of all compounds and also has a significant impact on the kinetic parameters. Toxicity evaluation of the DES and economic assessment of DES vs. ionic liquids (ILs) were performed. The synthesis cost of the DES is lower than that of ILs, and Escherichia coli JM109 survivability assessment confirms the DES as a non-toxic solvent. The present study provides valuable insights into the sequential extraction for a high-value multiproduct biorefinery.

Seasonal variations in the proximate (protein, carbohydrate, dietary fiber, ash, moisture, lipid, amino acid and fatty acid content), mineral composition (Na, K, Ca, Mg, Fe, Zn, C, Mn) and Heavy metals content (Cd, Pb, Hg and Ni) of Ulva compressa and Ulva fasciata were investigated for all four different seasons (Spring, North east monsoon, Summer and South west monsoon) during 2015 to 2016. Data were analyzed using one- and two-way ANOVA. Significant variations in the proximate constituents were found among seasons and species. Maximum proximate and mineral composition in U. compressa are protein, carbohydrate, ash content, moisture content and lipid in northeast monsoon, dietary fiber, amino acids content and mineral content in southwest monsoon, fatty acids content in spring. Heavy metals were not detected except lead. In U. fasciata, maximum proximate and mineral composition are protein, carbohydrate, moisture content, ash content in spring season, dietary fiber in summer season, lipid and total amino acids content in northeast monsoon, fatty acids contents and mineral content in southwest season. Heavy metals were not detected except lead. U. compressa has highest protein, carbohydrate, moisture content, amino acids and mineral content as compared to U. fasciata. U. fasciata has maximum dietary fiber, ash content, lipid content and fatty acids as compared to U. compressa. In general, Northeast monsoon showed the highest proximate and mineral composition in both the algae. The present study revealed that these two edible algae have higher proximate contents which can be more ideal for food consumption for humans and animals.

In this study, the feasibility of banana straw (BS) hydrolysate as carbon source and reutilizing the pretreated liquor (PL) of BS in the Rhodosporidium toruloides fermentation was explored for the first time. When BS hydrolysate was used as the carbon source, total biomass concentration, lipid concentration, and lipid content under optimal conditions reached 15.52 g/L, 5.83 g/L, and 37.56% (w/w), respectively, which was similar to the results of pure sugar control. After detoxification, 50% PL can be returned to enzymatic hydrolysis and fermentation, and total biomass concentration, lipid concentration, and lipid content can reach 15.14 g/L, 5.59 g/L, and 36.91% (w/w). Then, ethanol stillage (ES) was used as the nitrogen source. The NaCl and glycerol of ES could promote lipid accumulation, reaching 7.52 g/L under optimized conditions. Finally, microbial lipid production from BS hydrolysate and ES without any additional nutrients was investigated, and the maximum total biomass concentration, lipid concentration, and lipid content were 13.55 g/L, 4.88 g/L, and 36.01% (w/w), respectively. Besides, the main compositions of microbial lipid produced were C16 and C18, and the biodiesel production from the microbial lipid could meet Chinese and US standard through theoretical numerical calculation.

Today’s society is faced with many upfront challenges such as the energy crisis, water pollution, air pollution, and global warming. The greenhouse gases (GHGs) responsible for global warming include carbon dioxide (CO2), methane (CH4), nitrous oxide (NOx), water vapor (H2O), and fluorinated gases. A fraction of the increased emissions of CO2 in the atmosphere is due to agricultural and municipal solid waste (MSW) management systems. There is a need for a sustainable solution which can degrade the pollutants and provide a technology-based solution. Hence, the present work deals with the custom design of a loop photobioreactor with 34 L of total volume used to handle different inlet CO2 concentrations (0.03%, 5%, and 10% (v/v)). The obtained values of biomass productivity and CO2 fixation rate include 0.185 ± 0.004 g L−1 d−1 and 0.333 ± 0.004 g L−1 d−1, respectively, at 10% (v/v) CO2 concentration and 0.084 ± 0.003 g L−1 d−1 and 0.155 ± 0.003 g L−1 d−1, respectively, at 5% (v/v) CO2 concentration. The biochemical compositions, such as carbohydrate, proteins, and lipid content, were estimated in the algal biomass produced from CO2 mitigation studies. The maximum carbohydrate, proteins, and lipid content were obtained as 20.7 ± 2.4%, 32.2 ± 2.5%, and 42 ± 1.0%, respectively, at 10% (v/v) CO2 concentration. Chlorophyll (Chl) a and b were determined in algal biomass as an algal physiological response. The results obtained in the present study are compared with the previous studies reported in the literature, which indicated the feasibility of the scale-up of the process for the source reduction of CO2 generated from waste management systems without significant change in productivity. The present work emphasizes the cross-disciplinary approach for the development of bio-mitigation of CO2 in the loop photobioreactor.

The unsafe disposal of milk processing effluents has a negative impact on the environment due to their high content of nutrients and organic matter. Green alternatives can be applied to effectively manage and valorize these effluents, reducing their environmental footprint. The ability of the free-living cyanobacterium Oscillatoria sp. to grow in real cheese whey was evaluated as a potential strategy for integrating dairy wastewater treatment with biomass valorization. Autotrophic and mixotrophic cultures were maintained under controlled laboratory conditions and monitored over 28 days for growth, cell viability, biomass, pigment content, and physicochemical parameters, including pH, protein, carbohydrate, and chemical oxygen demand (COD). Oscillatoria sp. successfully adapted to the initial acidic conditions of the effluent (pH 2.8-2.9), increasing the pH of the treated whey to levels suitable for industrial wastewater disposal (pH 6.0-9.0). A 5-fold increase in dehydrogenase activity was observed after a 28-day culture, with no signs of oxidative damage. Cyanobacterial biomass cultivated under mixotrophic conditions displayed a significant reduction (∼55%) in photosynthetic pigments, including chlorophyll a and total carotenoids, compared to autotrophic cultures. Notably, Oscillatoria sp. biomass increased by 2.3-fold under mixotrophy, compared to the autotrophic control. The higher biomass production was accompanied by a significant reduction in the whey COD from 35,250 mg/L to 8500 mg/L, along with a 65% and 80% decrease in protein and carbohydrate content, respectively. These findings provide new insights into the metabolic behavior of Oscillatoria sp. during cheese whey bioremediation, highlighting the potential of mixotrophic cyanobacteria for managing dairy wastewater management.

This study aimed to optimize the growth conditions of the microalgae Auxenochlorella protothecoides to maximize the biomass and lipid content. The pH values and acetate concentrations of a tris-acetate-phosphate medium were varied for a photoheterotrophically grown culture of A. protothecoides. Approximately 23% of the microalgal biomass consisted of saturated fatty acids (SFAs). The highest lipid content (47.8%) was achieved with a medium containing 17 mM acetate at pH 6.2, and a medium containing 50 mM acetate at pH 5.8 resulted in the highest SFA content (43.7%). Surface response methodology was used to analyze the effects of two independent variables, pH (5.8–7.2) and acetate (0–35 mM), on lipid and biomass content. Four quadratic models, using the Box-Wilson central composite design, were proposed to correlate the optimal pH and acetate concentrations that would achieve the maximum biomass and lipid content. The study demonstrated that medium containing 24.4 mM acetate at pH 5.96 resulted in the highest lipid content (47.8%), and resulted in the highest biomass (1537 mg/L). Microalgae growth under these optimized conditions can enhance biomass and lipid productivity and can provide suitable conditions for high-quality biodiesel.

Biomass valorization of agriculture wastewater grown freshwater diatom Nitzschia sp. for metabolites, antibacterial activity, and biofertilizer

A two-stage process for hydrogen production from cheese whey: Integration of dark fermentation and biocatalyzed electrolysis

Cheese whey and cheese factory wastewater treatment with a biological anaerobic—aerobic process

The effect of amylase on growth performance, survival rate and proximate composition of Perinereis cultrifera was investigated. The amylase produced by Bacillus sp. was added to polychaete basal diets at three concentrations such as 50, 100 and 150 mg kg−1 in experiments I, II and III, respectively. After 90 days, polychaete receiving the diets supplemented with enzymes at 150 mg kg−1 showed significantly better growth performance and survival rate than those fed the basal diet (Control). Among these experimental animals, the maximum protein, lipid, carbohydrate and ash contents were recorded in experiment III, whereas moisture content was maximum in control and minimum in experiment III. The essential fatty acids such as palmitic acid (C16:0), margaric acid (C17:0), stearic acid (C18:0) and arachidonic acid (C20:4ω-6) occurred at higher concentration in experiment group than in control. Thus, the amylase produced by Bacillus sp. significantly influenced growth, survival rate and proximate composition of P. cultrifera which has importance in aquaculture industry.

Two experiments were conducted to investigate the chemical and fermentative characteristics of by-product-mixed silages consisting of wheat straw (WS), grape pomace (GP), olive mill wastewater (OMWW) and cheese whey (CW) at 7, 30 and 90 days. The silage formulations were based on a ratio of 60% solids (WS + GP) and 40% liquids (CW + OMWW), with the addition of water (W) where necessary to achieve 40% of liquids. In experiment 1, the effects of the inclusion of GP or CW in a mixture of WS and OMWW were studied according to two silage formulations: SIL-A, WS40% + OMWW5% + GP20% + W35%; SIL-B, WS60% + OMWW5% + CW35%. In experiment 2, the effects of two levels of CW and the inclusion of OMWW in mixed silages based on WS, GP, and CW were studied according to four silage formulations: SIL-C, WS40% + GP20% + CW20% + W20%; SIL-D, WS40% + GP20% + CW20% + OMWW5% + W15%; SIL-E, WS40% + GP20% + CW35% + W5%; SIL-F, WS40% + GP20% + CW35% + OMWW5%. In experiment 1, the silage formulation affected the chemical composition showing a greater (p < 0.05) content of DM in SIL-B; crude protein, ether extract and ADL contents were higher (p < 0.05) in SIL-A. In experiment 2, no differences (p > 0.05) in the chemical characteristics of the silages were found. In both of the experiments, the chemical composition and total phenol content did not change (p > 0.05) during the ensiling period. Fermentative characteristics were not affected (p > 0.05) by the by-product combination nor the ensiling period and proved to be adequate for good-quality silages. The Flieg’s scores at D30 and D90 were greater than a 100 score in all the experimental silages, leading to the conclusion that WS, GP, OMWW and CW can be effective for producing silage.

The decline in fossil fuel reserves has forced researchers to seek out alternatives to fossil fuels. Microalgae are considered to be a promising feedstock for sustainable biofuel production. Previous studies have shown that urea is an important nitrogen source for cell growth and the lipid production of microalgae. The present study investigated the effect of different concentrations of urea combined with kelp waste extract on the biomass and lipid content of Chlorella sorokiniana. The results revealed that the highest cell density, 20.36 × 107 cells−1, and maximal dry biomass, 1.70 g/L, were achieved in the presence of 0.5 g/L of urea combined with 8% kelp waste extract. Similarly, the maximum chlorophyll a, b and beta carotenoid were 10.36 mg/L, 7.05, and 3.01 mg/L, respectively. The highest quantity of carbohydrate content, 290.51 µg/mL, was achieved in the presence of 0.2 g/L of urea and 8% kelp waste extract. The highest fluorescence intensity, 40.05 × 107 cells−1, and maximum total lipid content (30%) were achieved in the presence of 0.1 g/L of urea and 8% kelp waste extract. The current study suggests that the combination of urea and kelp waste extract is the best strategy to enhance the biomass and lipid content in Chlorella sorokiniana.

Biomass and lipid enhancement in Chlorella sp. with emphasis on biodiesel quality assessment through detailed FAME signature