Resource recovery from food-processing wastewaters in a circular economy: a methodology for the future.

Food-processing wastewater (FPWW), as opposed to solid residues, occurs extensively throughout the world, and has considerable potential for resource recovery (RR), however, at present, it is severely underutilized. This paper serves as a suggested 'plan forward' to optimize integrated RR from FPWW. In order to optimize this potential and 'close the loop', there needs to be further development in in-depth analytical methods of the FPWW; axenic/mixed cultures or microbial communities capable of growing on FPWW and hence producing single-cell protein for animal feed and food additives; cost-effective methods for separating high-value-added solutes such as vitamins K2, B12, and B2; isoflavones and flavanones; integrated energy- and water-recovery flowsheets; and optimization methods to integrate RR and energy harvesting with minimal impact on the environment. Each of these areas is examined and future research directions are laid out.

Anaerobic membrane bioreactor performance with varying feed concentrations of ciprofloxacin.

The anaerobic membrane bioreactor (AnMBR) has considerable potential for treating wastewater, although there is very little data on the effect of antibiotics on AnMBR performance. This study examined the effect of Ciprofloxacin (CIP) - an antibiotic that can occur at high concentrations, and has a substantial impact on ecosystems, on AnMBR performance. The long-term (44 days) presence of 0.5 mg/L CIP in the feed did not have a strong effect on COD removal, volatile fatty acid (VFA) accumulation, or methane yield, but did affect the pH, soluble microbial products (SMPs) and suspended solids. However, at 4.7 mg/L CIP, a significant effect on all the parameters tested was seen. 16S rRNA gene-based community analysis demonstrated that CIP changed the phylogenetic structure and altered the species richness and diversity. The relative abundance of various genera was also changed, and this explained much of the change in AnMBR behavior.

Linkage of community composition and function over short response time in anaerobic digestion systems with food fermentation wastewater.

We investigated the short-term dynamics of microbial composition and function in bioreactors with inocula collected from full-scale and laboratory-based anaerobic digestion (AD) systems. The Bray-Curtis dissimilarity of both inocula was approximately 10% of the predicted Kyoto Encyclopedia of Genes and Genomes pathway and 40% of the taxonomic composition and yet resulted in a similar performance in methane production, implying that the variation of community composition may be decoupled from performance. However, the significant correlation of volatile fatty acids with taxonomic variation suggested that the pathways of AD could be different because of the varying genus. The predicted function of the significantly varying genus was mostly related to fermentation, which strengthened the conclusion that most microbial variation occurred within the fermentative species and led to alternative routes to result in similar methane production in methanogenic bioreactors. This finding sheds some light on the understanding of AD community regulation, which depends on the aims to recover intermediates or methane.

Comparison of soluble microbial product (SMP) production in full-scale anaerobic/aerobic industrial wastewater treatment and a laboratory based synthetic feed anaerobic membrane system.

This study focused on the characterisation of soluble microbial products (SMPs) produced from a full-scale multi-stage (anaerobic/aerobic) industrial wastewater treatment plant, and contrasted them to the SMPs detected in the effluent of a lab-scale AnMBR treating synthetic wastewater to determine if there were any common solutes detected irrespective of the feed organics. Recently developed analytical methods using gas chromatography coupled mass spectrometry (GC-MS) and liquid chromatography coupled quadrupole-time-of-flight (LC-Q-ToF) for SMP characterisation in a wide molecular weight (MW) range of 30-2000 Da (Da) were applied. Samples collected from the Industrial Wastewater plant were the upflow anaerobic sludge blanket (UASB) influent and effluent, and aerobic membrane bioreactor (MBR) effluent before discharge. The GC-MS detected a spike in cyclooctasulphur in the UASB effluent, an indicator of shock-loading, which disappeared after the MBR process. Alkanes, acids and nitrogenous compounds were found to be the end-products from the GC-MS results, while LC-Q-ToF analysis revealed that eicosanoids, a group of cell-signalling molecules, were produced in the aerobic MBR, and made up 71% of its effluent. A comparison of the submerged anaerobic membrane bioreactor (SAMBR) and aerobic MBR effluents using GC-MS showed that there was only a small degree of similarity between the SMPs, comprising mainly long chain alkanes and phthalate. On the other hand, LC-Q-ToF showed a large contrast in compound composition, mostly having cell-signalling functions, which deepened our understanding of the different metabolic processes occurring in aerobic and anaerobic systems. These data could be useful for future work in various areas such as controlling quorum-sensing and biofilm formation, process optimisation and control, and microbial ecology.

Datasets on the optimization of alginate extraction from sargassum biomass using response surface methodology.

This article presents data associated with the extraction of sodium alginate from waste Sargassum seaweed in the Caribbean utilizing an optimization approach using Response Surface Methodology [1]. A Box-Behnken (BBD) Response Surface Methodology using Design Expert 10.0.3 software on the alkaline extraction process was used. Data consists of the effects of 4 process variables (temperature, extraction time, alkali concentration and excess volume of alkali: dried seaweed) on the yield of sodium alginate. The model was validated, and extracts were characterization using High Performance Liquid Chromatography (HPLC), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). The data illustrates the applicability of our model in potentially valorizing this waste product into a valuable resource. Furthermore, our methodology can be applied to other macroalgae for efficient extraction of sodium alginate of commercial quality.

Alginate extraction from Sargassum seaweed in the Caribbean region: Optimization using response surface methodology.

Sargassum valorization has become increasingly important as the Caribbean region continues to struggle with the massive growth of the seaweed and its damaging effects. Sodium alginate extraction is one method where the seaweed biomass can be utilized to produce a useful biopolymer. However, current processing generally giving low yields of inferior quality, making it unattractive for commercialization. This article seeks to optimize the extraction process using a Box-Behnken Response Surface Design combined with multistage extraction to obtain higher product yield and purity, as well as giving insights, for the first time, into the physiochemical properties of the extracted alginate from Sargassum biomass. Optimum conditions were found and confirmed through validation, with a crude yield as high as 28 % after 2 stages and a purity of 92 % for purified alginate samples. Characterization of the bleached alginate through NMR studies validated with FTIR, gave an M/G ratio of 0.45 with a molecular weight of 3.14 × 105 g mol-1 and viscosity of 14.10 cP aligned to high gelling capabilities.

Composition and biotransformational changes in soluble microbial products (SMPs) along an anaerobic baffled reactor (ABR).

This work examined the production and catabolism/biotransformation dynamics of SMPs down the length of an eight-compartment-anaerobic baffled reactor (ABR) which physically separates the biological processes, in contrast to completely mixed reactors which do not enable these dynamics to measured, and this is totally novel. SMPs were extracted and characterised by gas and liquid chromatography coupled mass spectrometry to determine their composition and production/catabolism. 60%-70% of the feed compounds decreased from the first to fourth compartment; the increase in SMPs after the fourth compartment suggested a mixture of degraded and biotransformed compounds, and microbial products. High concentrations of low MW alkanes and alkenes, and higher MW (up to 2000 Da) lipids and amino acid derivatives accumulate in the last compartment at pseudo-steady state, and past work identifying polysaccharides/peptides as major membrane biofoulants have excluded these lipids. In addition, lipids and changes detected during feed transients have not been noted before in previous work. Finally, feed step-increases also increased some amino acid derivatives used in cell-signalling. Interestingly, some natural products from plant and fungal extracts were also found in the fourth compartment, where methanogenesis was the dominant process.

Identification of the production and biotransformational changes of soluble microbial products (SMP) in wastewater treatment processes: A short review.

While the definition of soluble microbial products (SMP) remains somewhat contentious, they have been widely accepted to be the pool of organic compounds which are released by cells into their surroundings (liquid or otherwise) due to substrate metabolism and biomass decay. SMPs are also potential precursors of disinfection by-products, and are known to be important in membrane fouling. With recent developments in analytical methodologies, many of the low molecular weight (MW) compounds can now be identified, although they are often incorrectly identified as recalcitrant compounds present in the influent. The old hypothesis of "microbial infallibility" suggested that all organic compounds produced by bacteria will eventually be degraded by microorganisms. However, there are some limitations to this hypothesis due to; the time available for degradation, the rate of activity of the microorganisms themselves, synergistic effects, as well as the degree of complexity of the chemical substance. Therefore, it is important to identify and characterise the SMPs involved in these processes, which can then in turn support the research and development of improving wastewater treatment efficiency and effectiveness, and eventually reduce environmental damage. In addition, it is still unclear what the evolutionary purpose of these compounds are. This paper reviews the work that has been done on the production and biotransformation of chemical compounds up to now and which were reported to be found in wastewater treatment systems.

Current applications of Colloidal Liquid Aphrons: Predispersed solvent extraction, enzyme immobilization and drug delivery.

Colloidal Liquid Aphrons (CLAs) are micron sized discrete spherical solvent droplets formed by the dispersion of polyaphrons into a bulk aqueous phase at a low phase volume ratio where they can be kept homogenously suspended with only minimal agitation. CLAs have high stability due to the presence of a surfactant 'shell' surrounding the solvent core, and possess large surface areas per unit volume for mass transfer due to their small size. Therefore, CLAs are well suited for applications in pre-dispersed solvent extraction (PSE), enzyme immobilization, and have the potential to be used as a drug delivery system. Using PSE, CLAs have been used to remove metals such as Ni2+, Cu2+, Fe3+, Cr3+ and Mg2+ from dilute streams, separate organic dyes such as Yellow 1 from wastewater, extract succinic and lactic acid, reactively extract phenylalanine, and separate suspensions. CLAs have also been used to immobilize enzymes such as lipase, lysozyme and albumins with cases of superactivity being reported due to the influence of surfactant and solvent interactions with the enzyme. Furthermore, due to their similarity to current drug delivery systems such as microemulsions and hydrogels, and other advantages, CLA systems have the potential to be adapted for drug delivery systems also. This article provides a complete list of the current applications of Colloidal Liquid Aphrons (CLAs) in PSE and enzyme immobilization, and also presents insight into how CLAs can be utilized as a drug delivery method in the future. Finally, this review ends by summarizing potentially interesting research areas to pursue in this field.

Alginate as a support ligand for enhanced colloidal liquid aphron immobilization of proteins and drug delivery.

Research within the field of colloidal liquid aphrons (CLAs) for enzyme immobilization has often used ionic surfactants for the retention of enzymes. Although these charged interactions allow for enhanced immobilization, they can often lead to denaturation of enzyme activity, and even release of the protein. Sodium alginate has been used in drug delivery applications due to its low toxicity and charged interactions that allow for encapsulation. Hence, alginate systems can be used as an alternative to ionic surfactants in CLA immobilization. This paper presents, for the first time, the use of sodium alginate as potential ligand for enhanced CLA immobilization. The use of five model proteins; lysozyme, bovine serum albumin, ovalbumin, insulin, and α-chymotrypsin, of various pIs and hydrophobicities, showed the relevance of electrostatic interactions in promoting binding with sodium alginate when the pH < pI, with 100% immobilization attributed to alginate incorporated CLAs over general nonionic formulations. Furthermore, above their pI, >80% protein recovery was observed, with activity and conformation comparable to their native counterparts. Finally, the use of proteolysis showed that as the degree of ionic bonding increased between the protein and sodium alginate, the degree of protease resistance decreased due to conformational changes experienced during binding.

Wastewater To Resource: Design of a Sustainable Phosphorus Recovery System.

To enable a more sustainable wastewater treatment processes, a transition towards resource recovery methods that have minimal environmental impact while being financially viable is imperative. Phosphorus (P) is a finite resource that is being discharged into the aqueous environment in excessive quantities. As such, understanding the financial and environmental effectiveness of different approaches for removing and recovering P from wastewater streams is important to reduce the overall impact of wastewater treatment. In this study, a process-systems modelling framework for comprehensively evaluating these approaches in terms of both economic and environmental impacts is developed. Applying this framework, treatment pathways are designed, simulated and analysed to determine the most suitable approaches for P removal and recovery. The purpose of this methodology is not only to assist with plant design, but also to identify the principal economic and environmental factors acting as barriers to implementing a given technology, incorporating the impact of waste recovery. The results suggest that the chemical and ion-exchange approaches studied deliver sustainable advantages over biological pathways, both economically and environmentally, with each possessing different strengths. The assessment methodology developed enables a more rational and environmentally sound wastewater plant design approach to be taken.

Fate and removal of Ciprofloxacin in an anaerobic membrane bioreactor (AnMBR).

This study examined the removal of varying concentrations of the antibiotic Ciprofloxacin (CIP) over the long-term (120 days) in an anaerobic membrane bioreactor (AnMBR). The results showed that 50-76% CIP was removed with 0.5-1.5 mg CIP/L in the feed, although at 4.7 mg/L its removal efficiency decreased to <20%. It was found that biological degradation was the main mechanism for removing CIP, while adsorption onto the sludge only contributed a small fraction, and an even smaller fraction was due to the waste sludge discharged. CIP was biodegraded to some degree in the AnMBR, with some intermediate compounds detected using LC-MS/MS and GC-MS. This work showed the effectiveness of an AnMBR in removing CIP at low concentrations of <1.5 mg/L, and hence may be an effective treatment for removing other antibiotics from wastewater.

Size-dependent microbial diversity of sub-visible particles in a submerged anaerobic membrane bioreactor (SAnMBR): Implications for membrane fouling.

Sub-visible particles, an often-overlooked fine particle (0.45-10 µm) with a size between sludge solids and soluble microbial products (SMP), have recently been identified as a critical foulant in anaerobic membrane bioreactors (AnMBRs), and our recent new insights into the size-fractionation and composition of sub-visible particles in AnMBRs have enabled fouling to be understood in more depth. Here, we investigated the microbial diversity of the sub-visible particles in three size fractions (i.e., 5-10, 1-5, and 0.45-1 µm) from bulk and cake solutions in a lab-scale AnMBR, and their fouling potential was further explored based on their filtration behavior and biofilm formation. Results show that with decreasing particle size, a significant shift in microbial communities was observed for the sub-visible particles in both bulk and cake solutions; (a) with notable decreases in filamentous microbes in the order SJA-15, GCA004, and Anaerolineales of phylum Chloroflexi, and, (b) with substantial increases in sulfate-reducing bacteria (i.e., the family Syntrophobacteraceae, genus DCE29 of family Thermodesulfovibrionaceae, Desulfovibrio, and Geobacter). More importantly, the filamentous microbes associated with micro-particles (5-10 µm) led to higher cake fouling resistances while free living cells in the form of colloidal particles (0.45-1 µm) induced severer pore blocking. Moreover, the micro-particles had an enhanced capacity to favor biofilm formation (OD595 = 1.0-2.5, categorized as highly positive), thus potentially aggravating biofouling. This work advances our knowledge on the effect of particle size on communities and underlying fouling behavior of microbes associated with fine particles in AnMBRs.

Autoinducer-2-mediated quorum sensing partially regulates the toxic shock response of anaerobic digestion.

This study discovered a strong correlation between the autoinducer-2 (AI-2)-mediated quorum sensing (QS) with the performance of a submerged anaerobic membrane bioreactor during its recovery from a pentachlorophenol (PCP) shock: a decrease in AI-2 levels coincided with a reduction in volatile fatty acid concentrations, and corresponded significantly to a decrease in the relative abundance of Firmicutes, and to an increase in the relative abundance of Bacteroidetes and Synergistetes. Further batch experiments with the addition of an AI-2-regulating Escherichia coli mutant culture showed that a reduction in AI-2 levels resulted in the highest biogas production rate during a PCP shock. In contrast, an increase in AI-2 levels via addition of the E. coli wild type strain or an AI-2 precursor showed no obvious effects on biogas production. These results suggest that the AI-2 level in anaerobic sludge was governed primarily by Firmicutes, and the AI-2-mediated QS partially regulates the toxic shock response of anaerobic sludge via tuning the activities of Firmicutes and Synergistetes. A decrease in the AI-2 level might reduce acetogenesis and favor hydrogenotrophic methanogenesis, thus resulting in less VFA accumulation and higher methane production during the PCP shock. This study is the first of this type that exploits the role of quorum sensing in the toxic shock response of anaerobic sludge; it demonstrates a novel approach to shortening the recovery period of anaerobic processes via manipulating the AI-2-mediated QS.

Emergency response facilities including primary and secondary prevention strategies across 79 professional football clubs in England.

AIM: To assess the emergency response planning and prevention strategies for sudden cardiac arrest (SCA) across a wide range of professional football clubs in England. METHODS: A written survey was sent to all professional clubs in the English football league, namely the Premiership, Championship, League 1 and League 2. Outcomes included: (1) number of clubs performing cardiac screening and frequency of screening; (2) emergency planning and documentation; (3) automated external defibrillator (AED) training and availability; and (4) provision of emergency services at sporting venues. RESULTS: 79 clubs (86%) responded to the survey. 100% clubs participated in cardiac screening. All clubs had AEDs available on match days and during training sessions. 100% Premiership clubs provided AED training to designated staff. In contrast, 30% of lower division clubs with AEDs available did not provide formal training. Most clubs (n=66; 83%) reported the existence of an emergency action plan for SCA but formal documentation was variable. All clubs in the Premiership and League 1 provided an ambulance equipped for medical emergencies on match days compared with 75% of clubs in the Championship and 66% in League 2. CONCLUSIONS: The majority of football clubs in England have satisfactory prevention strategies and emergency response planning in line with European recommendations. Additional improvements such as increasing awareness of European guidelines for emergency planning, AED training and mentorship with financial support to lower division clubs are necessary to further enhance cardiovascular safety of athletes and spectators and close the gap between the highest and lower divisions.

Post-treatment of anaerobic membrane bioreactor (AnMBR) effluent using activated carbon.

Anaerobic membrane bioreactors (AnMBR) are very effective for wastewater treatment, however, with the antibiotic ciprofloxacin (CIP) (0-4.7 mg CIP/L) in the feed their performance decreases, the characteristics of the effluent changes, and further treatment is needed to recycle or discharge the treated effluent. Batch experiments using six activated carbons to treat AnMBR effluents resulting from the treatment of a synthetic wastewater containing ciprofloxacin were carried out at 35 °C. 22-82% COD was removed at a dose of 1 g activated carbon/L, while size characterization showed the 13.4 kDa and <1 kDa fractions were the most difficult to adsorb, while CIP was often removed with high efficiencies of mainly 100%. Significant removal of VFAs also occurred, up to 100%, and this contributed greatly to COD removal. Nitrogen containing compounds and phenols showed the highest removal (∼100%), whereas other groups such as esters, alkanes, and alkenes showed lower removal efficiency.

The effect of Fe2NiO4 and Fe4NiO4Zn magnetic nanoparticles on anaerobic digestion activity.

Two types of magnetic nanoparticles (MNPs), i.e. Ni ferrite nanoparticles (Fe2NiO4) and Ni Zn ferrite nanoparticles (Fe4NiO4Zn) containing the trace metals Ni and Fe, were added to the anaerobic digestion of synthetic municipal wastewater at concentrations between 1 and 100 mg Ni L-1 in order to compare their effects on biogas (methane) production and sludge activity. Using the production of methane over time as a measure, the assays revealed that anaerobic digestion was stimulated by the addition of 100 mg Ni L-1 in Fe2NiO4 NPs, while it was inhibited by the addition of 1-100 mg Ni L-1 in Fe4NiO4Zn NPs. Especially at 100 mg Ni L-1, Fe4NiO4Zn NPs resulted in a total inhibition of anaerobic digestion. The metabolic activity of the anaerobic sludge was tested using the resazurin reduction assay, and the assay clearly revealed the negative effect of Fe4NiO4Zn NPs and the positive effect of Fe2NiO4 NPs. Re-feeding fresh synthetic medium reactivated the NPs added to the anaerobic sludge, except for the experiment with 100 mg Ni L-1 addition of Fe4NiO4Zn NPs. The findings in this present study indicate a possible new strategy for NPs design to enhance anaerobic digestion.

Effect of ciprofloxacin on methane production and anaerobic microbial community.

This study investigated the effects and fate of CIP on anaerobic sludge over a wide range of concentrations (0.05-50 mg/L), and 0.5-50 mg/L significantly inhibited organic removal and methanogenic activity, increased volatile fatty acids accumulation and low molecular weight soluble microbial products (SMPs), including p-cresol and nitrogen-containing compounds. Although microbial communities exposed to CIP did not differ significantly from the control in species diversity indices, Syntrophobacter and Methanothrix associated with acetogenesis and acetoclastic methanogenesis, respectively, were underrepresented in the CIP-exposed communities. Our study advances understanding of how environmentally relevant concentrations of CIP disrupts anaerobic digestion, which has important implications for anaerobic engineered systems treating CIP-bearing waste streams.

Downstream protein separation by surfactant precipitation: a review.

In a conventional protein downstream processing (DSP) scheme, chromatography is the single most expensive step. Despite being highly effective, it often has a low process throughput due to its semibatch nature, sometimes with nonreproducible results and relatively complex process development. Hence, more work is required to develop alternative purification methods that are more cost-effective, but exhibiting nearly comparable performance. In recent years, surfactant precipitation has been heralded as a promising new method for primary protein recovery that meets these criteria and is a simple and cost-effective method that purifies and concentrates. The method requires the direct addition of a surfactant to a complex solution (e.g. a fermentation broth) containing the protein of interest, where the final surfactant concentration is maintained below its critical micelle concentration (CMC) in order to allow for electrostatic and hydrophobic interactions between the surfactant and the target protein. An insoluble (hydrophobic) protein-surfactant complex is formed and backextraction of the target protein from the precipitate into a new aqueous phase is then carried out using either solvent extraction, or addition of a counter-ionic surfactant. Importantly, as highlighted by past researchers, the recovered proteins maintain their activity and structural integrity, as determined by circular dichroism (CD). In this review, various aspects of surfactant precipitation with respect to its general methodology and process mechanism, system parameters influencing performance, protein recovery, process selectivity and process advantages will be highlighted. Moreover, comparisons will be made to reverse micellar extraction, and the current drawbacks/challenges of surfactant precipitation will also be discussed. Finally, promising directions of future work with this separation technique will be highlighted.

Fate and behavior of dissolved organic matter in a submerged anoxic-aerobic membrane bioreactor (MBR).

In this study, the production, composition, and characteristics of dissolved organic matter (DOM) in an anoxic-aerobic submerged membrane bioreactor (MBR) were investigated. The average concentrations of proteins and carbohydrates in the MBR aerobic stage were 3.96 ± 0.28 and 8.36 ± 0.89 mg/L, respectively. After membrane filtration, these values decreased to 2.9 ± 0.2 and 2.8 ± 0.2 mg/L, respectively. High performance size exclusion chromatograph (HP-SEC) analysis indicated a bimodal molecular weight (MW) distribution of DOMs, and that the intensities of all the peaks were reduced in the MBR effluent compared to the influent. Three-dimensional fluorescence excitation emission matrix (FEEM) indicated that fulvic and humic acid-like substances were the predominant DOMs in biological treatment processes. Precise identification and characterization of low-MW DOMs was carried out using gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis indicated that the highest peak numbers (170) were found in the anoxic stage, and 54 (32%) compounds were identified with a similarity greater than 80%. Alkanes (28), esters (11), and aromatics (7) were the main compounds detected. DOMs exhibited both biodegradable and recalcitrant characteristics. There were noticeable differences in the low-MW DOMs present down the treatment process train in terms of numbers, concentrations, molecular weight, biodegradability, and recalcitrance.