Utilization of wastewater from edible oil industry, turning waste into valuable products: A review

The way forward to produce nutraceuticals from agri-food processing residues: obstacle, solution, and possibility

Food matrices contain bioactive compounds that have health benefits beyond nutritional value. The bulk of bioactive chemicals are still present in agro-industrial by-products as food matrices. Throughout the food production chain, there is a lot of agro-industrial waste that, if not managed effectively, could harm the environment, company, and how nutritiously and adequately people eat. It's important to establish processes that maximise the use of agro-industrial by-products, such as biological technologies that improve the extraction and acquisition of bioactive compounds for the food and pharmaceutical industries. As opposed to nonbiological processes, biological procedures provide high-quality, bioactive extracts with minimum toxicity and environmental impact. Fermentation and enzymatic treatment are biological processes for obtaining bioactive compounds from agro-industrial waste. In this context, this article summarises the principal bioactive components in agro-industrial byproducts and the biological methods employed to extract them. In this review efficient utilization of bioactive compounds from agro-industrial waste more effectively in food and pharmaceutical industries has been described.

Experimental investigation on sludge conditioning and dewatering using an agricultural biomass coupled with resource recovery

In this study, the effect of modified areca husk fibre biochar (MAFB-AlCl3) on dairy sludge conditioning and dewatering along with raw and modified coconut shell biochar (MCSB-FeCl3) was investigated. Further, MgO impregnated biochars of areca husk fibre and coconut shells was carried out to evaluate the performance on phosphate recovery from the diary sludge. The enhancement in sludge dewatering with MAFB-AlCl3 were evaluated experimentally and significant reduction of capillary suction time (CST) (51.6 %), moisture content (18%), zeta potential (1.3 mV) and increased settleability (32.7%) were observed. The sludge conditioning parameters namely dosage (% of dry solids (DS)), rapid mixing time (RMT), slow mixing time (SMT) were optimized by response surface methodology for the modified biochars. Optimum CST (31.51 s) was obtained at dosage (50 % of DS), RMT (9.89 min) and SMT (17.23 min). Results of batch study for phosphate recovery by MgO impregnated biochars (MgB) was found to be 96.6 % and 100 % by MgB of areca husk fibre (MgAFB) and coconut shells (MgCSB) respectively. The morphological characteristics and elemental distribution using field emission scanning electron microscopy (FE-SEM) & energy dispersive X-ray spectroscopy (EDS) reveals the structural change in the sludge particles for the modified biochars as well as for sludge. Hence MAFB-AlCl3, MgAFB and MgCSB is proved to be suitable and an effective candidate for sludge conditioning and dewatering coupled with phosphate recovery in handling the diary sludge.

Gas chromatography ion mobility spectroscopy: A rapid and effective tool for monitoring oil oxidation

Oil autoxidation is an early process of food deterioration, monitoring oil oxidation is therefore of great significance to ensure food quality and safety. In this study, a detection method of the primary and secondary oxidative products was developed by gas chromatography ion mobility spectrometry (GC-IMS).The secondary oxidative products was analyzed by GC-IMS. Then, the relationships between peroxide values and the contents of secondary oxidative products were investigated by constructing a prediction model of peroxide value of rapeseed oil with the help of secondary oxidative products and chemometrics. The coefficient of determination Q2 of the model validation set is 0.96, and the RMSECV is 0.1570 g/100 g. These validation results indicated that secondary oxidative products could also reflect the content of the primary oxidative products. Moreover, 10 characteristic markers related to oxidative rancidity were identified for monitoring edible oil rancidity and oxidative stability.

Construction and application of highly efficient waste cooking oil degrading bacteria consortium in oily wastewater

The treatment of cooking oil wastewater is an urgent issue need to be solved. We aimed to screen for efficient oil-degrading bacteria and develop a new microbial agent for degrading waste cooking oil in oily wastewater. Three extremely effective oil-degrading bacteria, known as YZQ-1, YZQ-3, and YZQ-4, were found by the enrichment and acclimation of samples from various sources and separation using oil degradation plates. The 16S rRNA sequencing analysis and phylogenetic tree construction showed that the three strains were Bacillus tropicus, Pseudomonas multiresinivorans, and Raoultella terrigena. Under optimal degradation conditions, the maximal degradation rates were 67.30 ± 3.69%, 89.65 ± 1.08%, and 79.60 ± 5.30%, respectively, for YZQ-1, YZQ-3, and YZQ-4. Lipase activity was highest for YZQ-3, reaching 94.82 ± 12.89 U/L. The best bacterial alliance was obtained by adding equal numbers of microbial cells from the three strains. Moreover, when this bacterial alliance was applied to oily wastewater, the degradation rate of waste cooking oil was 61.13 ± 7.30% (3.67% ± 2.13% in the control group), and COD removal was 62.4% ± 5.65% (55.60% ± 0.71% in the control group) in 72 h. Microbial community analysis results showed YZQ-1 and YZQ-3 were adaptable to wastewater and could coexist with local bacteria, whereas YZQ-4 could not survive in wastewater. Therefore, the combination of YZQ-1 and YZQ-3 can efficiently degrade oil and shows great potential for oily wastewater treatment.

Identification of pressed and extracted vegetable oils by headspace GC-MS

Edible vegetable oils are produced either by mechanical pressing or extraction. Although pressing retains the inherent flavor and nutritional value of the oil, the oil yield is low and the process expensive. Extraction methods have high oil yields, low processing costs, and economic benefits; however, No. 6 solvent, which may pose potential risks to human health, is commonly used in the extraction and cleaning process. Differentiating extracted oil containing these solvents from pressed oil, for quality control, based on visual appearance is difficult. Hence, in this study, an identification method using the characteristic components of solvent No. 6 under optimized headspace Gas chromatography-mass spectrometry (GC-MS) conditions was established. It also provided a reference for quality control of industrial production by estimating the amount of solvent present in the oil. Results showed that, in addition to five main components (2-methylpentane, 3-methylpentane, and n-hexane, Methylcyclopentane, Cyclohexane), accounting for 97% of the solvent, No. 6 solvent also contains 16 types of organic substances, such as olefins, aromatic hydrocarbons, and polycyclic aromatic hydrocarbons. Under optimized headspace GC-MS conditions (headspace sampler equilibrium temperature = 150 °C), the No. 6 solvent exhibits high linearity over a concentration range of 0.05-1 mg/kg with a correlation coefficient of 0.999 and a detection limit of 0.01 mg/kg. Pressed and extracted oils can be determined as follows: If three or fewer main components of the No. 6 solvent are detected, and the total content of No. 6 solvent is less than 0.5 mg/kg, it is a pressed oil; if four or more main components of No. 6 solvent are detected, or the total content of No. 6 solvent is ≥0.5 mg/kg, it is confirmed as an extracted oil.

Subcritical and Supercritical Fluids to Valorize Industrial Fruit and Vegetable Waste

The valorization of industrial fruit and vegetable waste has gained significant attention due to the environmental concerns and economic opportunities associated with its effective utilization. This review article comprehensively discusses the application of subcritical and supercritical fluid technologies in the valorization process, highlighting the potential benefits of these advanced extraction techniques for the recovery of bioactive compounds and unconventional oils from waste materials. Novel pressurized fluid extraction techniques offer significant advantages over conventional methods, enabling effective and sustainable processes that contribute to greener production in the global manufacturing sector. Recovered bio-extract compounds can be used to uplift the nutritional profile of other food products and determine their application in the food, pharmaceutical, and nutraceutical industries. Valorization processes also play an important role in coping with the increasing demand for bioactive compounds and natural substitutes. Moreover, the integration of spent material in biorefinery and biorefining processes is also explored in terms of energy generation, such as biofuels or electricity, thus showcasing the potential for a circular economy approach in the management of waste streams. An economic evaluation is presented, detailing the cost analysis and potential barriers in the implementation of these valorization strategies. The article emphasizes the importance of fostering collaboration between academia, industry, and policymakers to enable the widespread adoption of these promising technologies. This, in turn, will contribute to a more sustainable and circular economy, maximizing the potential of fruit and vegetable waste as a source of valuable products.

Response of aerobic activated sludge to edible oil exposure: Extracellular polymeric substance (EPS) characteristics and microbial community

Aerobic activated sludge is widely used to degrade edible oil wastewater in wastewater treatment plants. During this process, the observed poor organics removal performance might be caused by poor sludge settling performance, which might be influenced by extracellular polymeric substances (EPS) and the structure of the microbial community. However, this hypothesis was not confirmed. Thus, this study investigated the response of activated sludge to 50% and 100% edible oil exposure in comparison to glucose, focusing on organics removal performance, characteristics of sludge, EPS, and microbial community structure. Results showed that both concentrations of edible oil influenced the systems' performance, although 100% edible oil showed more significant negative effects than 50% edible oil. The mechanisms behind the influence of edible oil on the aerobic activated sludge system and the differences between the different concentrations of edible oil were revealed. The worse system performance in the edible oil exposure system was due to the worse sludge settling performance, which was significantly affected by edible oil (p < 0.05). The sludge settling performance was mainly inhibited by promoting the formation of floating particles and the enrichment of filamentous bacteria in the 50% edible oil exposure system; biosurfactant secretion was also speculated as the reason, in addition to the above factors, in the 100% edible oil exposure system. The macroscopic largest floating particles, highest total relative abundance of foaming bacteria and biosurfactant production genera (34.32%), lowest surface tension (43.7 mN/m), and highest emulsifying activity (E₂₄ = 25%) of EPS in 100% edible oil exposure systems provide strong evidence.

Bioaugmentation and enhanced formation of biogranules for degradation of oil and grease: Start-up, kinetic and mass transfer studies

Biogranulation technology is an emerging biological process in treating various wastewater. However, the development of biogranules requires an extended period of time when treating wastewaters with high oil and grease (O&G) content. A study was therefore conducted to assess the formation of biogranules through bioaugmentation with the Serratia marcescens SA30 strain, in treating real anaerobically digested palm oil mill effluent (AD-POME), with O&G of about 4600 mg/L. The biogranules were developed in a lab-scale sequencing batch reactor (SBR) system under alternating anaerobic and aerobic conditions. The experimental data were assessed using the modified mass transfer factor (MMTF) models to understand the mechanisms of biosorption of O&G on the biogranules. The system was run with variable organic loading rates (OLR) of 0.69-9.90 kg/m³d and superficial air velocity (SAV) of 2 cm/s. After 60 days of being bioaugmented with the Serratia marcescens SA30 strain, the flocculent biomass transformed into biogranules with excellent settleability with improved treatment efficiency. The biogranules showed a compact structure and good settling ability with an average diameter of about 2 mm, a sludge volume index at 5 min (SVI₅) of 43 mL/g, and a settling velocity (SV) of 81 m/h after 256 days of operation. The average removal efficiencies of O&G increased from 6 to 99.92%, respectively. The application of the MMTF model verified that the resistance to O&G biosorption is controlled via film mass transfer. This research indicates successful bioaugmentation of biogranules using the Serratia marcescens SA30 strain for enhanced biodegradation of O&G and is capable to treat real AD-POME.

Concentrating emulsified oily wastewater by integrated membrane technology

The effects of operating pressure, feed temperature, oil content of feed solution, and membrane surface flow rate on membrane flux, concentration multiple, and average particle size of oil droplets in the concentrated solution during the single-stage membrane concentration process were investigated. The experimental results show that within a certain operating range, the membrane flux increases with the increase of operating pressure, feed temperature, and membrane surface flow rate, while it decreases continuously with the increase of feed oil content. Optimal conditions for single stage concentration based on membrane flux, concentration factor, and average particle size of oil droplets in the concentrated solution were determined. Then, on the basis of single-stage membrane concentration conditions, three different pore size separation membranes are combined in different ways. After concentration through multi-stage membranes, the particle size of the oil droplets in the concentrate is greater than 20 μm, which is beyond the particle size range of the emulsified oil, and the concentration of the oil in the concentrate is 20-30 times that of the original oil. The method can realize the recovery of oil resources in the emulsified oil-containing wastewater.

A hypothetical model of multi-layered cost-effective wastewater treatment plant integrating microbial fuel cell and nanofiltration technology: A comprehensive review on wastewater treatment and sustainable remediation

Wastewater management has emerged as an uprising concern that demands immediate attention from environmentalists worldwide. Indiscriminate and irrational release of industrial and poultry wastes, sewage, pharmaceuticals, mining, pesticides, fertilizers, dyes and radioactive wastes, contribute immensely to water pollution. This has led to the aggravation of critical health concerns as evident from the uprising trends of antimicrobial resistance, and the presence of xenobiotics and pollutant traces in humans and animals due to the process of biomagnification. Therefore, the development of reliable, affordable and sustainable technologies for the supply of fresh water is the need of the hour. Conventional wastewater treatment often involves physical, chemical, and biological processes to remove solids from the effluent, including colloids, organic matter, nutrients, and soluble pollutants (metals, organics). Synthetic biology has been explored in recent years, incorporating both biological and engineering concepts to refine existing wastewater treatment technologies. In addition to outlining the benefits and drawbacks of the current technologies, this review addresses novel wastewater treatment techniques, especially those using dedicated rational design and engineering of organisms and their constituent parts. Furthermore, the review hypothesizes designing a multi-bedded wastewater treatment plant that is highly cost-efficient, sustainable and requires easy installation and handling. The novel setup envisages removing all the major wastewater pollutants, providing water fit for household, irrigation and storage purposes.

Effects of urban wastewater application on growth, biomass, nutrition, and heavy-metal accumulation of Populus nigra L. "62/154," P. alba L. "20/45," P. euramericana (Dode) Guinier "92/40," and Salix excelsa S.G. Gmel grown in heavy-metal contaminated soil

Iran is located in a dry climate zone, and climate change has substantially reduced its precipitation and water resources. Reusing wastewaters from urban communities can meet some requirements for irrigation and fertilization of tree plantations in arid environments, leading to sustainable wastewater recycling, enhanced biomass production, and reduced land degradation. The objective of this study was to test the growth, biomass, nutrition, and heavy-metal accumulation of poplars [Populus nigra L. "62/154," P. alba L. "20/45," P. euramericana (Dode) Guinier "92/40"], and willow (Salix excelsa S.G. Gmel) in a pot experiment at four and eight months after planting when grown in soils irrigated with tap water (SITW) and wastewater (SIWW). After four months, SIWW treatment had no significant effect on growth, biomass, nor absorption of macronutrients. After eight months, SIWW treatment of poplars and willow significantly (p = 0.000) increased: (1) height, (2) leaf area, (3) root, stem, leaf, and total biomass, and (5) phytoextraction and phytoaccumulation of macro-/micro-nutrients and heavy metals in tree tissues, over trees receiving the SITW treatment. There were significant differences in growth, biomass, and accumulation of micronutrients and heavy metals in poplar versus willow tissues, with the highest biomass production and tissue-specific content of heavy metals in P. nigra trees, and the greatest total concentrations of heavy metals in P. alba and S. excelsa trees. In contrast, uptake of Fe, Cu, Ni, Cr and Pb were similar between poplar and willow, and phytoaccumulation of these elements was primarily in the roots. Leaf concentrations were highest for Zn and Mn. While P. nigra outperformed all other species overall, tolerance index (TI; defined as the tolerance to the heavy metals as calculated by the ratio of the biomass of SIWW trees relative to SITW trees) values exceeding 100% for all one-year-old poplar and willow trees demonstrated that they can be considered for planting in soil affected by urban wastewaters with similar contaminant profiles as in the current study.

Contactless Discharge-Driven Method for Separation of Oil-Water Mixtures

Oil-water separation technology has potential applications in wastewater treatment, petroleum refining and edible oil processing. As the ultimate means in oil-water treatment, electrostatic coalescence technology has been widely used in oil fields and refineries. However, the technology has many problems, such as complex processes, electrode corrosion, and the inability to treat high-water-cut crude oil emulsions. Here, we propose a contactless method of oil-water separation by corona discharge. With corona discharge of a needle-plate electrode configuration, the oil droplet diffuses to the ITO glass surface and the water droplet oscillates at the edge of the PET film. Here, such droplet behaviors are described in detail. Based on the motion behavior of the oil and water droplet, we designed an efficient oil-water separation device. After the oil-water mixture passes through the device, the oil content in the oil region can reach 99.25% with a voltage of 8 kV. In addition, the separation speed of the oil-water mixture can also be adjusted by varying the corona discharge voltage. This paper presents a simple and innovative method for oil-water separation.

Garcinia gummi-gutta seeds: a novel source of edible oils

BACKGROUND

Edible oils are important for human nutrition and health. The demand for edible oils is increasing globally and the situation warrants the identification of new natural sources of oils that have been subjected to proper quality and safety evaluation. Garcinia gummi-gutta is a widely cultivated fruit crop in Kerala, south India. The fruit rinds are the useful part, while the seeds are treated as waste material. This study evaluated the composition, physico-chemical properties, and toxicity of the seed oil with a view to considering its utility in the food sector.

RESULTS

The yield of oil obtained from the seeds of Garcinia gummi-gutta through hexane extraction was 335.30 g kg^-1 . The physico-chemical parameters of the oil were determined through nuclear magnetic resonance (NMR) studies. The values agree well with those of conventional edible oils. Stearic acid, a saturated fatty acid, was identified as the main component (55.39%) followed by monounsaturated oleic acid (40.22%) through gas chromatography-mass spectrometry (GC-MS) analysis of fatty acid methyl esters (FAMEs). Preliminary in vivo acute oral toxicity studies and acute dermal toxicity studies on female Wistar rats, and dermal irritation studies on New Zealand white male rabbits showed no morbidity, mortality, appreciable change in the bodyweight, or clinical signs of dermal responses.

CONCLUSIONS

The results suggest that the seeds of G. gummi-gutta are a rich source of edible oil. The presence of stearic acid, a stable fatty acid, as the major constituent suggests that the oil could be suitable for use in value-added food products such as chocolates. Preliminary toxicological studies also recommend the use of the oil in the food and cosmetics sectors. © 2021 Society of Chemical Industry.

Trends in mitigation of industrial waste: Global health hazards, environmental implications and waste derived economy for environmental sustainability

Majority of industries, in order to meet the technological development and consumer demands generate waste. The untreated waste spreads out toxic and harmful substances in the environment which serves as a breeding ground for pathogenic microorganisms thus causing severe health hazards. The three industrial sectors namely food, agriculture, and oil industry are among the primary organic waste producers that affect urban health and economic growth. Conventional treatment generates a significant amount of greenhouse gases which further contributes to global warming. Thus, the use of microbes for utilization of this waste, liberating CO₂ offers an indispensable tool. The simultaneous production of value-added products such as bioplastics, biofuels, and biosurfactants increases the economics of the process and contributes to environmental sustainability. This review comprehensively summarized the composition of organic waste generated from the food, agriculture, and oil industry. The linkages between global health hazards of industrial waste and environmental implications have been uncovered. Stare-of-the-art information on their subsequent utilization as a substrate to produce value-added products through bio-routes has been elaborated. The research gaps, economical perspective(s), and future research directions have been identified and discussed to strengthen environmental sustainability.

Photosynthetic bacteria with iron oxide nanoparticles as catalyst for cooking oil removal and valuable products recovery with heavy metal co-contamination

Waste cooking oil discharge causes environmental pollution in receiving waters, particularly when associated with heavy metals that can lead to formation of hazardous organometallic compounds. This study combined iron oxide nanomaterial and the anoxygenic photosynthetic bacterium Rhodopseudomonas faecalis PA2 for removal of cooking oil in the presence of heavy metals. R. faecalis PA2, with known capability to generate beneficial substances from several wastes, was capable of cooking oil removal with production of valuable products. Oil removal, biomass, protein, and carotenoid production were 82.38%, 1.48 g/L, 1,600.19 mg/L, and 1,046.33 mg/L, respectively, under optimal conditions (cooking oil as carbon source and 30% inoculum density). Iron (Fe) stimulates growth of R. faecalis; in this study, Fe₃O₄ nanoparticles were synthesized and used as a catalyst to facilitate interaction and high reactivity between Fe and R. faecalis PA2. Size measurement by transmission electron microscopy (17.44 nm), X-ray diffraction peaks, and magnetic susceptibility confirmed that the synthesized nanoparticles were magnetite Fe₃O₄. Biomass, protein, and carotenoid production of the Fe₃O₄ supplemented experiment increased by 61.56%, 70.78%, and 57.2%, respectively, when compared with the control. When different concentrations of heavy metals (Pb, Ni, Co, and Zn) were supplemented in the media containing cooking oil, Fe₃O₄ addition increased heavy metal tolerance, improved bacterial growth, and enhanced valuable products when compared with the non-supplemented group. This study reports the positive impact of nanoparticle application as a catalyst for valorization of cooking oil waste with heavy metal co-contamination by the photosynthetic bacterium R. faecalis PA2.

Photopolymerized superhydrophobic hybrid coating enabled by dual-purpose tetrapodal ZnO for liquid/liquid separation

Low-cost and scalable superhydrophobic coating methods provide viable approaches for energy-efficient separation of immiscible liquid/liquid mixtures. A scalable photopolymerization method is developed to functionalize porous substrates with a hybrid coating of tetrapodal ZnO (T-ZnO) and polymethacrylate, which exhibits simultaneous superhydrophobicity and superoleophilicity. Here, T-ZnO serves dual purposes by (i) initiating radical photopolymerization during the fabrication process through a hole-mediated pathway and (ii) providing a hierarchical surface roughness to amplify wettability characteristics and suspend liquid droplets in the metastable Cassie-Baxter regime. Photopolymerization provides a means to finely control the conversion and spatial distribution of the formed polymer, whilst allowing for facile large-area fabrication and potential coating on heat-sensitive substrates. Coated stainless-steel meshes and filter papers with desired superhydrophobic/superoleophilic properties exhibit excellent performance in separating stratified oil/water, oil/ionic-liquid, and water/ionic-liquid mixtures as well as water-in-oil emulsions. The hybrid coating demonstrates desired mechanical robustness and chemical resistance for their long-term application in large-scale energy-efficient separation of immiscible liquid/liquid mixtures.

Statistical optimization of lipase production from oil mill effluent by Acinetobacter sp. KSPE71

The present study investigated the valorization of oil-rich residues of coconut oil mill effluent (COME) as a potential growth medium for the microbial production of extracellular lipase. The bacterial species isolated from oil mill effluent, Acinetobacter sp. KSPE71 was tested for its efficiency to grow and produce lipase in undiluted COME and 0.2 % yeast extract and 0.2 % NH4Cl sup-plemented COME. In this connection, the process parameters such as pH, temperature, agitation speed, and inoculum size were optimized to maximize the production using a central composite design in the Response surface methodology. At the optimized state of pH 7.5, 35 ?C, 150 rpm with 0.6 % inoculum size, a maximum of 3.95 U mL-1 activity was obtained, four-fold higher than the basal condition. At this stage, 73 % of the lipid content was degraded. The present work results imply that the oil mill effluent can be used as a cheaper production medium for lipase and the new isolate Acinetobacter sp. KSPE71 as a potential lipase producer. The degradation of oil waste along with the production of the valuable product has multiple advantages of cost reduction of lipase and environmental concern.

A review on the potential of polyhydroxyalkanoates production from oil-based substrates

Polyhydroxyalkanoate (PHA) is a type of polyesters produced in the form of accumulated intracellular granules by many microorganisms. It is viewed as an environmentally friendly bioproduct due to its biodegradability and biocompatibility. The production of the PHA using oil substrates such as waste oil and plant oil, has gained considerable attention due to the high product yield and lower substrate cost. Nevertheless, the PHA fermentation using oil substrate is complicated due to the heterogenous fatty acid composition, varied bio-accessibility and possible inhibitory effect on the bacterial culture. This review presents the current state-of-the-art of PHA production from oil-based substrates. This paper firstly discusses the technical details, such as the choice of bacteria strain and fermentation conditions, characteristic of the oil substrate as well as the PHA composition and application. Finally, the paper discusses the challenges and prospects for up-scaling towards a cleaner and effective bioprocess. From the literature review, depending on the cell culture and the type of PHA produced, the oil platform can have a PHA yield of 0.2-0.8 g PHA/g oil substrate, with PHA content mostly from 40 to 90% of the cell dry weight. There is an on-going search for more effective oil-utilising PHA producers and lower cost substrate for effective PHA production. The final application of the PHA polymer influences the treatment needed during downstream processing and its economic performance. PHA with different compositions exhibits varied decomposition behaviour under different conditions, requiring further insight towards its management towards a sustainable circular economy.

Research advancement and commercialization of microalgae edible oil: a review

The global food crisis has led to a great deal of attention being given to microalgal oil as a sustainable natural food source. This article provides an overview of the progress and future directions in promoting the commercialization of microalgal edible oils, including microalgal triglyceride accumulation, suitable edible oil culture strategies for high nutritional value, metabolic engineering, production, and downstream technologies. The integration of the production process, biosafety, and the economic sustainability of microalgal oil production are analyzed for their critical roles in the commercialization of microalgal edible oil to provide a theoretical and scientific basis for the comprehensive development and utilization of microalgal edible oil. © 2021 Society of Chemical Industry.

Utilizing treated wastewater in tree plantation in Indian desert: part I - species suitability, plant growth and biomass production

Treated wastewater can partly meet the requirements of water for irrigating tree crops in dry areas to better utilize, produce biomass and reduce land degradation. Seedlings of Acacia nilotica, Azadirachta indica, Eucalyptus camaldulensis, Prosopis cineraria, P. juliflora, Tamarix aphylla, Salvadora persica, S. oleoides and Tecomella undulata were planted and irrigated with bore-well (BW) and treated wastewater (WW) at ½ET (Evaporation-transpiration) and ¾ET. Plants irrigated at BW1/2 attained less height and collar diameter, and showed low growth increments and dry biomass. These variables increased by 1.2-2.0-fold at WW3/4 irrigation. Plants produced 1.4-fold higher biomass with WW over BW, whereas it was 1.5-fold higher at ¾ET over ½ET. Responses of species to BW/WW irrigation differed in biomass allocation to roots and other parts as a mechanism to uptake water and nutrients. Conclusively, A. nilotica, A. indica, P. juliflora and T. aphylla had stronger preference to increased irrigation level, whereas E. camaldulensis, S. persica, S. oleoides and T. undulata had preferred nutrients added through treated wastewater. A. nilotica, E. camaldulensis, P. juliflora and A. indica were best species in growth and biomass production and wastewater utilization. These can be replicated in urban afforestation to enhance bio-product and reduce degradation in environmental quality.

Environment and food safety: a novel integrative review

Environment protection and food safety are two critical issues in the world. In this review, a novel approach which integrates statistical study and subjective discussion was adopted to review recent advances on environment and food safety. Firstly, a scientometric-based statistical study was conducted based on 4904 publications collected from the Web of Science Core Collection database. It was found that the research on environment and food safety was growing steadily from 2001 to 2020. Interestingly, the statistical analysis of most-cited papers, titles, abstracts, keywords, and research areas revealed that the research on environment and food safety was diverse and multidisciplinary. In addition to the scientometric study, strategies to protect environment and ensure food safety were critically discussed, followed by a discussion on the emerging research topics, including emerging contaminates (e.g., microplastics), rapid detection of contaminants (e.g., biosensors), and environment friendly food packaging materials (e.g., biodegradable polymers). Finally, current challenges and future research directions were proposed.

Roles and applications of enzymes for resistant pollutants removal in wastewater treatment

Resistant pollutants like oil, grease, pharmaceuticals, pesticides, and plastics in wastewater are difficult to be degraded by traditional activated sludge methods. These pollutants are prevalent, posing a great threat to aquatic environments and organisms since they are toxic, resistant to natural biodegradation, and create other serious problems. As a high-efficiency biocatalyst, enzymes are proposed for the treatment of these resistant pollutants. This review focused on the roles and applications of enzymes in wastewater treatment. It discusses the influence of enzyme types and their sources, enzymatic processes in resistant pollutants remediation, identification and ecotoxicity assay of enzymatic transformation products, and typically employed enzymatic wastewater treatment systems. Perspectives on the major challenges and feasible future research directions of enzyme-based wastewater treatment are also proposed.

A novel strategy for triacylglycerides and polyhydroxyalkanoates production using waste lipids

Lipids are one of the main components of the organic matter present in the effluents of the food-processing industry. These waste streams can be biotransformed into valuable triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs), precursors of biofuels and biomaterials alternative to petroleum-based products. These compounds are yielded by mixed microbial cultures, and considering that both TAG and PHA accumulators may coexist within the community, it seems crucial to define those operational strategies that might control the selection of the dominant metabolic pathways (TAG or PHA accumulation). In this work, residual fish-canning oil was used as a carbon source in a two-stage process (culture selection and intracellular compounds accumulation) in which the substrate was simultaneously hydrolyzed in these two stages without the need for a previous fermentation unit. It was pretended to maximize preferential TAG or PHA storage in the accumulation reactor by the imposition of certain selective pressures in the enrichment one. Uncoupling C and N feedings and limiting nitrogen availability in the medium, allowed to maximize PHA production (82.3 wt% of PHAs, 0.80 Cmmol_PHA/Cmmol_S). Besides, when low pH in the famine phase was considered as additional selective pressure, it was possible to shift the ratio TAG:PHA from 4:96 obtaining 43.0 wt% of TAGs (0.67 Cmmol_TAG/Cmmol_S). Therefore, this novel and simplified process demonstrated versatility and efficiency in the storage of TAGs and PHAs from a unique residual feedstock and using an open culture proving that product selection can be harnessed if choosing the right operational conditions in the enrichment stage.

A new bioremediation method for removal of wastewater containing oils with high oleic acid composition: Acinetobacter haemolyticus lipase immobilized on eggshell membrane with improved stabilities

As a result of the increasing demand for edible oils, which are an important part of human nutrition, in recent years, serious environmental problems may arise both during the production and after consumption of these oils.

Valorization of by-products from olive oil industry and added-value applications for innovative functional foods

BACKGROUND

In the last years, the consumption of olive oil has experienced a sharp rise due to its organoleptic and healthy properties and with this the wastes and by-products derived from the olive production and the olive oil industry have also increased causing important environmental and economic issues. However, the high content in bioactive compounds of these wastes and by-products makes that its recovery is both a great challenge and an excellent opportunity for the olive oil sector.

AIM OF THE REVIEW

This review encompasses the more outstanding aspects related to the advances achieved until date in the olive oil by-products valorisation and added-value applications for innovative functional foods.

CONCLUSION

Taking into account the information reported in this manuscript, the development of a multiproduct biorefinery in cascade using eco-friendly technologies interchangable seems a suitable stratety to obtaining high added value compounds from olive oil by-products with applications in the field of innovative functional foods. In addition, this would allow an integral valorization of these residues enhancing the profitability of the olive oil industry. On the other hand, the biocompounds fom olive oil by-products have been described by their interesting bioactivities with beneficial properties for the consumers' health; therefore, their incorporation into the formulation of functional foods opens new possibilities in the field of innovative foods. Future perspective: Despite the studies descibed in the literature, more research on the healthy properties of the recovered compounds and their interactions with food components is key to allow their reintegration in the food chain and therefore, the removal of the olive oil by-products.

Oily Wastewater Treatment Using Polyamide Thin Film Composite Membrane Technology

In this study, polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membrane filtration was used in edible oil wastewater emulsion treatment. The PA-TFC membrane was characterized using mechanical, thermal, chemical, and physical tests. Surface morphology and cross-sections of TFCs were characterized using SEM. The effects of edible oil concentrations, average droplets size, and contact angle on separation efficiency and flux were studied in detail. Purification performance was enhanced using activated carbon as a pre-treatment unit. The performance of the RO unit was assessed by chemical oxygen demand (COD) removal and permeate flux. Oil concentration in wastewater varied between 3000 mg/L and 6000 mg/L. Oily wastewater showed a higher contact angle (62.9°) than de-ionized water (33°). Experimental results showed that the presence of activated carbon increases the permeation COD removal from 94% to 99%. The RO membrane filtration coupled with an activated carbon unit of oily wastewater is a convenient hybrid technique for removal of high-concentration edible oil wastewater emulsion up to 99%. Using activated carbon as an adsorption pre-treatment unit improved the permeate flux from 34 L/m²hr to 75 L/m²hr.