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Can Microalgae Remove Pharmaceutical Contaminants from Water?
The increase in worldwide water contamination with numerous pharmaceutical contaminants (PCs) has become an emerging environmental concern due to their considerable ecotoxicities and associated health issues. Microalgae-mediated bioremediation of PCs has recently gained scientific attention, as microalgal bioremediation is a solar-power driven, ecologically comprehensive, and sustainable reclamation strategy. In this review, we comprehensively describe the current research on the possible roles and applications of microalgae for removing PCs from aqueous media. We summarize several novel approaches including constructing microbial consortia, acclimation, and cometabolism for enhanced removal of PCs by microalgae, which would improve practical feasibility of these technologies. Some novel concepts for degrading PCs using integrated processes and genetic modifications to realize algal-based bioremediation technologies are also recommended.
Water contamination with numerous pharmaceutical contaminants (PCs) has been one of the most important emerging environmental problems facing humanity due to their ecotoxicities and health issues.
Culturing microalgae in wastewater can create a ‘zero-waste concept’ and stimulate an effective and sustainable practice for the microalgae biofuel industry.
Constructing microbial consortia, acclimating microorganisms, and cometabolic approaches can improve the engineering feasibility of microalgae-based biotechnologies.
Some innovative concepts, such as integrated processes (algae-based technologies with advanced oxidation processes, constructed wetlands, and microbial fuel cells) and genetic modifications, can help to realize algae-based bioremediation technologies.
Journal Article
Using Microbial Aggregates to Entrap Aqueous Phosphorus
The increasing use and associated loss of phosphorus to the environment pose risks to aquatic ecosystems. Technology for phosphorus removal based on microbial aggregates is a natural, ecologically widespread, and sustainable reclamation strategy. Two main processes dominate phosphorus removal by microbial aggregates: extra- and intra-cellular entrapment. Extracellular phosphorus entrapment relies on extracellular polymeric substances, while intracellular entrapment uses a wider variety of phosphorus-entrapping mechanisms. In microbial aggregates, microalgae–bacteria interactions, quorum sensing, and acclimation can enhance phosphorus removal. Based on these insights, we propose novel avenues for entrapping phosphorus using ecological and genetic engineering, manipulated interactions, and integrated processes to create phosphorus removal technology mediated by microbial aggregates.
Phosphorus (P) entrapment by microbial aggregates is a natural process that requires relatively small amounts of operational inputs and is eco-friendly; it offers an effective means to remove P from eutrophic surface waters.Extracellular polymeric substances in microbial aggregates play an important role in extracellular P entrapment due to their inherent characteristics, chemical composition, and role in aggregation.Multiple mechanisms allow intracellular P entrapment by microalgae and polyphosphate-accumulating microorganisms in microbial aggregates.In microbial aggregates, microalgae–bacteria interactions, quorum sensing, and adaption can enhance the community’s ability to remove P.Ecological and genetic engineering, regulation of interactions, and integrated processes (microbial aggregates with enhanced biological P removal and bioelectrochemical system), can help to design P removal technology based on microbial aggregates.
Journal Article
An Extensive Analysis of Combined Processes for Landfill Leachate Treatment
Sanitary landfilling is the predominant process for solid urban waste disposal, but it generates leachate that poses environmental, economic, and social concerns. Landfill leachate (LL) contains complex and refractory pollutants and toxic compounds that can vary depending on landfill maturity, age, and biochemical reactions, making its treatment challenging. Due to its unique characteristics and occurrence in remote locations, LL requires separate treatment from wastewater. Various conventional treatment processes involving biological, chemical, and physical processes have been used for LL treatment, but a single treatment process is insufficient to meet environmental standards. This review demonstrates that combined treatment processes are more effective and efficient for LL treatment compared to single processes. Among the various combinations, chemical–chemical and chemical–biological treatments are the most commonly used. Specifically, the integration of Fenton with adsorption and a membrane bioreactor (MBR) with nanofiltration (NF) processes shows promising results. The combined processes of MBR with NF, Fenton with adsorption, and PF with biological treatment show maximum removal efficiencies for COD, reaching 99 ± 1%, 99%, 98%, and 97%, respectively. Additionally, the combined Fenton with adsorption process and EC with SPF process enhance biodegradability as indicated by increased BOD5/COD ratios, from 0.084 to 0.82 and 0.35 to 0.75, respectively. The findings emphasize the importance of developing and implementing enhanced combined treatment processes for LL, with the aim of achieving efficient and comprehensive pollutant mineralization. Such processes have the potential to address the environmental concerns associated with LL and contribute to sustainable waste management practices.
Journal Article
Upcycling chitin-containing waste into organonitrogen chemicals via an integrated process
Chitin is the most abundant renewable nitrogenous material on earth and is accessible to humans in the form of crustacean shell waste. Such waste has been severely underutilized, resulting in both resource wastage and disposal issues. Upcycling chitin-containing waste into value-added products is an attractive solution. However, the direct conversion of crustacean shell waste-derived chitin into a wide spectrum of nitrogen-containing chemicals (NCCs) is challenging via conventional catalytic processes. To address this challenge, in this study, we developed an integrated biorefinery process to upgrade shell waste-derived chitin into two aromatic NCCs that currently cannot be synthesized from chitin via any chemical process (tyrosine and L-DOPA). The process involves a pretreatment of chitin-containing shell waste and an enzymatic/fermentative bioprocess using metabolically engineered Escherichia coli. The pretreatment step achieved an almost 100% recovery and partial depolymerization of chitin from shrimp shellwaste (SSW), thereby offering water-soluble chitin hydrolysates for the downstream microbial process under mild conditions. The engineered E. coli strains produced 0.91 g/L tyrosine or 0.41 g/L L-DOPA from 22.5 g/L unpurified SSW-derived chitin hydrolysates, demonstrating the feasibility of upcycling renewable chitin-containing waste into value-added NCCs via this integrated biorefinery, which bypassed the Haber–Bosch process in providing a nitrogen source.
Journal Article
On the performance of electrocoagulation-assisted biological treatment processes: a review on the state of the art
The combined treatment systems have become a potential alternative to treat highly polluted industrial wastewater to achieve high-quality treated effluents. The current review focuses on the treatment systems compromising electrocoagulation (EC) as a pretreatment step followed by a biological treatment step. The reasons for applying EC as a pretreatment process were mainly to (1) detoxify the wastewater by removing inhibitors of the biotreatment step or (2) to remove the major part of the COD or (3) the dissolved materials that could cause fouling to membrane bioreactors or (4) to increase the activity of the microorganisms. This combination represents a new and promising application characterized by higher performance and removal efficiency. The main published findings related to this application are presented and analyzed. Besides, the statistical models used to optimize the process variables and the kinetics of microorganism growth rate are discussed herein. Most of the previous investigations were conducted in a laboratory-scale level with biologically treated water as a feed to the EC process. Only a few works applied a hybrid system consisting of the biological step and the EC step. In all studies, improved performance and higher removal efficiencies of the combined process were achieved particularly when applying aluminum electrodes, providing more than 95% removal efficiency. Many researchers have reported that they had faced a significant problem in the operation of the electrocoagulation process associated with the reduction of electrodes’ efficiency caused by deposits of the coagulation complex. This problem needs to be effectively resolved.
Journal Article
Natural Organic Matter Removal in Surface Water Treatment via Coagulation—Current Issues, Potential Solutions, and New Findings
Considerable changes have been observed in surface waters’ quality in recent years. They include an increase in dissolved organic carbon (DOC) concentrations, as well as a shift of natural organic matter (NOM) composition in favor of low molecular weight (LMW), and they are expected to occur on a wider scale in the future. Those predictions are particularly worrying given the importance of surface water as the main potable water source for numerous communities across the globe. Conventional methods of surface water treatment for drinking purposes mostly focus on the process of coagulation. The progressing changes in the quality of surface waters, however, render the conventional treatment via coagulation inefficient. The issue of the presence of natural organic matter in drinking water sources, its anticipated changes, and the related treatment problems are all complex and pressing matters that need addressing. This paper aims to provide a critical review of recent findings regarding NOM removal via coagulation in reference to the current NOM-related issues and their potential solutions. The paper discusses the application of different types of coagulants, and their respective advantages and disadvantages. Coagulation-integrated processes including adsorption, membrane filtration, biological processes, and oxidation are also addressed. Lastly, insights on the future approach to the discussed issues and conclusions are presented.
Journal Article
ESTIMATION AND INFERENCE IN THE PRESENCE OF FRACTIONAL d = 1/2 AND WEAKLY NONSTATIONARY PROCESSES
We provide new limit theory for functionals of a general class of processes lying at the boundary between stationarity and nonstationarity—what we term weakly nonstationary processes (WNPs). This includes, as leading examples, fractional processes with d = 1/2, and arrays of autoregressive processes with roots drifting slowly towards unity. We first apply the theory to study inference in parametric and nonparametric regression models involving WNPs as covariates. We then use these results to develop a new specification test for parametric regression models. By construction, our specification test statistic has a χ² limiting distribution regardless of the form and extent of persistence of the regressor, implying that a practitioner can validly perform the test using a fixed critical value, while remaining agnostic about the mechanism generating the regressor. Simulation exercises confirm that the test controls size across a wide range of data generating processes, and outperforms a comparable test due to Wang and Phillips (Ann. Statist. 40 (2012) 727–758) against many alternatives.
Journal Article
Integrated process planning and scheduling in networked manufacturing systems for I4.0: a review and framework proposal
Integrated process planning and scheduling in networked manufacturing systems plays a crucial role nowadays and in the forthcoming context of Industry 4.0 to enable effective and efficient decisions, and to improve the business market, based on collaboration, along with computer-based distributed manufacturing and management functions. In this paper some insights regarding a literature review carried out about this main subjects analysed are presented and discussed. Moreover, a framework for integrated process planning and scheduling in networked manufacturing systems is proposed and briefly described, along with some main underlying issues, which are further discussed. Thus, the main purpose of this research consists on presenting a proposed methodology, based on the study conducted, to enable to further assist either academia or industry to develop new tools, techniques and approaches for integrated process planning in networked manufacturing environments. The findings and contributions of this research can help in the implementation and improvement in distributed manufacturing environments, to be linked with small and medium enterprises, to further expand their potentialities through well suited integrated process planning and scheduling decision making processes.
Journal Article