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A recent focus has been on the recovery of single-cell protein and other nutritionally valuable bioproducts, such as Coenzyme Q10 (CoQ10) from purple non-sulfur bacteria (PNSB) biomass following wastewater treatment. However, due to PNSB's peculiar cell envelope (e.g., increased membrane cross-section for energy transduction) and relatively smaller cell size compared to wellstudied microbial protein sources like yeast and microalgae, the effectiveness of common cell disruption methods for protein quantification from PNSB may differ. Thus, this study examines the efficiency of selected chemical (NaOH and EDTA), mechanical (homogenization and bead milling), physical (thermal and bath/probe sonication), and combined chemical-mechanical/physical treatment techniques on the PNSB cell lysis. PNSB biomass was recovered from the treatment of gas-to-liquid process water. Biomass protein and CoQ10 contents were quantified based on extraction efficiency. Considering singletreatment techniques, bead milling resulted in the best protein yields (p < 0.001), with the other techniques resulting in poor yields. However, the NaOH-assisted sonication (combined chemical/physical treatment technique) resulted in similar protein recovery (p = 1.00) with bead milling, with the former having a better amino acid profile. For example, close to 50% of the amino acids, such as sensitive ones like tryptophan, threonine, cystine, and methionine, were detected in higher concentrations in NaOH-assisted sonication (>10% relative difference) compared to bead-milling due to its less disruptive nature and improved solubility of amino acids in alkaline conditions. Overall, PNSB required more intensive protein extraction techniques than were reported to be effective on other single-cell organisms. NaOH was the preferred chemical for chemicalaided mechanical/physical extraction as EDTA was observed to interfere with the Lowry protein kit, resulting in significantly lower concentrations. However, EDTA was the preferred chemical agent for CoQ10 extraction and quantification. CoQ10 extraction efficiency was also suspected to be adversely influenced by pH and temperature. [ABSTRACT FROM AUTHOR]

This review paper provides an overview of various types of photobioreactors (PBRs) that could be used for the production of polyhydroxyalkanoates (PHAs) using anoxygenic photoheterotrophs, with a focus on the design and operation of these systems. The paper highlights the potential of different PBRs based on reactor geometry and growth mode, and also examines the advantages and disadvantages of each PBR type and summarizes their suitability for PNSB-PHA production. The optimization of reactor design and operation is crucial for maximizing PNSB growth and PHA productivity. The self-immobilization of bacteria in granular sludge is a promising technology for wastewater treatment and the production of PHAs, while grooved-surface PBRs and porous-substrate PBRs have limitations due to difficult biomass harvesting in the former and the presence of aerobic conditions incongruent with PNSB culturing in the latter. Limitations exist with all solutions for maximizing rapid growth and maintaining high biomass concentrations due to the requirements of phototrophic growth. [ABSTRACT FROM AUTHOR]

The availability of agricultural wastewater in arid climes limits the possibility of exploiting purple non‐sulfur bacteria (PNSB) to recover aqua‐feed bioproducts. Thus, this study examines the feasibility of recovering such bioproducts using fuel‐synthesis process water (FSPW) as a feedstock. Experiments were performed under varying light conditions. The results revealed that PNSB cultured in the zero‐nitrogen feedstock had over 40 % protein content, contained substantial lipids and pigments, and reduced FSPW organics by over 70 %. The light intensity significantly impacted biomass constituents and treatment efficiency. The results are promising for the potential development of a circular economy to convert FSPW to aqua‐feed. [ABSTRACT FROM AUTHOR]

Within the frame of this article, briefly but comprehensively, we present the existing knowledge, perspectives, and challenges for the utilization of Layered Double Hydroxides (LDHs) as adsorbents against a plethora of pollutants in aquatic matrixes. The use of LDHs as adsorbents was established by considering their significant physicochemical features, including their textural, structural, morphological, and chemical composition, as well as their method of synthesis, followed by their advantages and disadvantages as remediation media. The utilization of LDHs towards the adsorptive removal of dyes, metals, oxyanions, and emerging pollutants is critically reviewed, while all the reported kinds of interactions that gather the removal are collectively presented. Finally, future perspectives on the topic are discussed. It is expected that this discussion will encourage researchers in the area to seek new ideas for the design, development, and applications of novel LDHs-based nanomaterials as selective adsorbents, and hence to further explore the potential of their utilization also for analytic approaches to detect and monitor various pollutants. [ABSTRACT FROM AUTHOR]

In the present study, the adsorption behavior of ciprofloxacin (CIP) from aqueous solution onto MWCNTs/Al2O3 was studied using batch experiments. Physical characterization of MWCNTs/Al2O3 was determined by SEM, XRD, and BET. The effective parameters investigated included: initial CIP concentration, contact time, MWCNTs/Al2O3 mass, and temperature. Based on experimental results and correlation coefficients, the rate of CIP adsorption followed the pseudo-second-model kinetics. Complete compatibility of the adsorption isotherm process was achieved with the Langmuir model, and the maximum adsorption capacity reached 41.73 mg/g under the optimized conditions (pH = 7, MWCNTs/Al2O3 dose = 1.2 g/L, contact time = 60 min, initial concentration = 10 mg/L, and temperature= 45 °C). The adsorption capacities based on the Langmuir model at different temperatures, 273, 288, 303, and 318 K, were equal to 72.18, 75.92, 79.65, and 83.47 mg/g, respectively. The determined parameters of the thermodynamic studies demonstrated the endothermic and spontaneous nature of the biosorption. The mean free energy was estimated from D–R isotherm model to be 0.316–0.707 KJ/mol, which clearly proved that the adsorption experiment followed a physical process. The data suggest that MWCNTs/Al2O3 could be used as a highly effective adsorbent material with a high capacity for the removal of antibiotics from water and wastewater. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) and lead (Pb) are toxic heavy metals commonly used in various industries. The simultaneous presence of these metals in wastewater amplifies the toxicity of wastewater and the complexity of the treatment process. This study has investigated the selective behavior of an aluminosilicate-based mesoporous adsorbent. It has been demonstrated that when equimolar quantities of the metals are present in wastewater, the adsorbent uptakes the Pb2+ ions selectively. This has been attributed to the higher electronegativity value of Pb2+ compared to Cd2+ which can be more readily adsorbed on the adsorbent surface, displacing the Cd2+ ions. The selectivity can be advantageous when the objective is the separation and reuse of the metals besides wastewater treatment. In non-equimolar solutions, a complete selectivity can be observed up to a threshold Pb2+ molar ratio of 30%. Below this threshold value, the Cd2+ and Pb2+ ions are uptaken simultaneously due to the abundance of Cd2+ ions and the availability of adsorption sites at very low Pb2+ molar ratios. Moreover, the total adsorption capacities of the adsorbent for the multi-component system have been shown to be in the same range as the single-component system for each metal ion which can be of high value for industrial applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Production of a novel activated adsorbent material from the non-metallic component of PCB waste. [•] High copper, zinc and lead removal capacities which are 3mmol/g, 2mmol/g and 3.4mmol/g, respectively. [•] Enhanced selective adsorption of heavy metals in multi-component systems. [•] Single equilibrium isotherm modeling-best fitted with Redlich–Peterson. [•] Binary equilibrium isotherm modeling-best fitted with modified extended Freundlich model. [ABSTRACT FROM AUTHOR]

With rapidly growing industrial development worldwide, the need for a new class of nanoparticles and techniques for treating wastewater remains a major concern to protect the environment. Layered double hydroxides and particularly LDH-containing hybrids are emerging as potential nano-sized adsorbents for water treatment. Recent studies have demonstrated LDH-containing hybrids as promising multifunctional materials for potential utilization in various applications such as, photo-catalysis, energy storage, nanocomposites and water purification. This article reviews the recent applications of LDH-containing hybrids as adsorbents for water remediation. The maximum adsorption capacities of various toxic heavy metals and dyes on different LDH hybrids were reported as 483 mg/g for Pb 2 + , 95 mg/g for Cd 2 + , 181 mg/g for Cu 2 + , 649 mg/g for Cr 6 + , 180 mg/g As 5 + , 813 mg/g for Hg 2 + , 450 for Ag + , 277 mg/g for U 6 + , 1062 mg/g for methyl orange, 185 mg/g for methylene blue, and 1250 mg/g for Congo red, which is comparatively higher than other commercial adsorbents. This review discusses the adsorption performance of manifold LDH-containing hybrids for treating various pollutants such as heavy metals and dyes. The mechanisms of interaction of LDH-containing hybrids with pollutants and the influence of key adsorption parameters such as pH, contact time, adsorbent dose and temperature have been comprehensively discussed. Moreover, the regeneration potential and reuse of spent LDH-containing hybrids and its toxicity effects have also been reviewed. [ABSTRACT FROM AUTHOR]

A low cost and high performing hybrid ceramic/carbon symmetric membrane has been fabricated and tested. The hybrid membrane was fabricated by mixing alumina powder with high surface area powdered activated carbon (PAC). The hybrid Al 2 O 3 /AC membrane has a developed complex network of micro and nano channels which enhanced the porosity of the membrane two fold compared to a pure Al 2 O 3 membrane. Furthermore, due to enhanced pore size and porosity, the hybrid membrane exhibited super-hydrophilic characteristics with the contact angle being close to zero. The increase in the membrane roughness enhanced the surface area of the membrane, which created an increase in the membrane surface area for the filtration path. The membrane exhibited a very high removal efficiency and retention (more than 99%) of oil from an oil-in-water emulsion stabilized by a surfactant. The membrane performance has been tested under harsh conditions such as a high oil concentration in a concentrated saline feed and no change in the separation efficiency or performance was observed with time. The membrane proved to be a good candidate for applications such as the treatment of oily wastewater or oil separation from seawater or from produced-water. [ABSTRACT FROM AUTHOR]

As a potential solution for water scarcity, the membrane bioreactor (MBR) has attracted much consideration in the field of wastewater treatment. In any case, MBRs have fouling issues which lead to a short membrane life and high operational costs. Henceforth, better antifouling polysulfone (PSU) nanocomposite membranes blended with polyethylene glycol functionalized carbon nanotubes (PEG-CNTs) were developed via non-solvent induced phase separation (NIPS) method. CNTs were chemically functionalized with PEG and their successful preparation was confirmed by SEM, FTIR, TGA, and XRD analyses. The fabricated nanocomposite membranes were characterized with respect to water uptake, hydrophilicity, bulk porosity, mean pore radius, and tortuosity. The effect of PEG-CNTs on the membrane morphology and mechanical strength was investigated by scanning electron microscope (SEM) and tensile testing, respectively. The filtration performance of nanocomposite membranes was evaluated by the filtration of water and protein solution. According to the results, the optimum blending of 0.25 wt% PEG-CNTs exhibited an approximately four-fold increase in water and protein permeabilities of 16.8 + 0.5 and 10.8 + 0.8 Lm −2 h −1 bar −1 , respectively. Moreover, the addition of PEG-CNTs in polysulfone membranes reduced the interaction between protein and membrane surface, thus improving the fouling resistance by 72.9 ± 1%. The optimized nanocomposite membrane could be a promising material with enhanced fouling control for wastewater treatment by MBR. [ABSTRACT FROM AUTHOR]

The water cleaning applications of carbon nanotubes (CNT) have generated much research interest since their initial discovery. However, in the early stages of research, the efficiency of CNTs for the removal of heavy metal ions has been severely limited because of the intense agglomeration of CNTs and their deficiency of functional groups. In this research, a new method has been discovered for the preparation of dendrimer functionalized CNTs and a PAMAM/CNT nanocomposite was prepared. FTIR, SEM, TEM, Raman spectroscopy, zeta potential measurements, and dispersion observing methods have been employed for characterizing the synthetic nanocomposite and these techniques indicated that the dendrimer functionalized CNTs have been favorably synthesized. In addition, the uniquely high adsorption capacities properties of PAMAM/CNT nanocomposite for Ni 2 + , Zn 2 + , As 3 + , Co 2 + were examined. The effects of several parameters including initial metal ion concentration, temperature, solution pH, the nanocomposite dosage and contact time were studied. The experimental data were analyzed using equilibrium isotherm relationships (Langmuir, Temkin and Freundlich) and the uniquely high adsorption capacities and rates were studied using (pseudo-first order, intraparticle diffusion and pseudo second-order) adsorption kinetics models. The results indicated that the maximum adsorption occurred at pH = 8. With increasing nanocomposite dosage and increasing contact time, there was increased adsorption capacity. Analysis of the adsorption process demonstrated that the Langmuir isotherm and pseudo-second order kinetics are the most appropriate models for heavy metal ions adsorption onto PAMAM/CNT nanocomposite. [ABSTRACT FROM AUTHOR]

Sludge, a byproduct produced from numerous industrial activities, has been recognized as an ecological burden for the society. However, viewing the sludge, as a carbon-rich material, has stimulated new gateways for the production of porous activated carbons for water treatment applications. Herein, various textural properties of the sludge-based activated carbons have been compiled and critically reviewed with the focus on surface area, pore size and pore size distribution for both physically and chemically activated carbons. It has been found that chemical activation using various activating agents yields more superior adsorbents with high specific surface areas than physical activation methods. Moreover, the potential of sludge-derived activated carbons for the sequestration of metals and dyes from aqueous media has been discussed. Furthermore, the adsorption mechanism in several adsorbent–adsorbate systems and the effect of various parameters on the adsorption behavior of different dyes and metals on sludge-based activated carbons have been reviewed. It has been shown that the pollutant uptake capacities of the adsorbents derived from sewage sludge are not only governed by the textural properties of the adsorbents, but also by their surface properties, such as the functional groups and the surface charge and thus it is proposed that both of these crucial factors be considered concurrently. [ABSTRACT FROM AUTHOR]

The recycling of waste printed circuit boards (PCBs) has become one of the global challenges in the technological era. The colossal volume of waste PCB generated annually coupled with its toxic nature and the existence of highly-precious metals in its composition intensifies the problems associated with waste PCB management and recycling. The two prevalent waste management options, landfill disposal and incineration, are being phased out for this special waste as a result of public health concerns. Hence, in the past few decades, several PCB recycling schemes are being introduced. The most efficient and environmentally-sound practice for waste PCB recycling has been the separation of metallic and nonmetallic fraction of PCBs by extensively-studied physico-mechanical approaches. Although the metallic fraction can be directly rendered into the market due to its high value, the nonmetallic fraction (NMF) is either disposed of in landfills causing secondary pollution or used as a low-value filler with the sole purpose of its safe disposal. This study presents a brief overview of the utilization of NMF as a filler in various industries. The main objective of the present review is to thoroughly examine the novel, highly efficient application of NMF as precursor for the production of a mesoporous structured adsorbent and its application in the removal of a myriad of heavy metals in single- and multi-component systems. In addition, the effects of the operational parameters on the adsorption behavior of the adsorbent material have been provided. Moreover, a comprehensive overview of the adsorption system modelling for single and binary-component systems for this novel material has been compiled. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel developed adsorbent material derived from waste printed circuit boards’ component. [•] The innovative adsorbent material can effectively remove cadmium ions from aqueous solutions. [•] The maximum capacity for cadmium ion removal is 2.1mmol/g. [•] Cadmium removal capacity is either equivalent or better than commercial resins. [Copyright &y& Elsevier]

Abstract: Printed circuit boards (PCBs) constitute one of the major sources of toxicity in landfill areas throughout the world. Hence, PCB recycling and separation of its metallic and nonmetallic components has been considered a major ecological breakthrough. Many studies focus on the metallic fraction of the PCBs due to its economic benefits whereas the nonmetallic powder (NMP) has been left isolated. In this work, the feasibility of using NMP as an adsorbent to remove charged toxic heavy metal ions have been studied and its efficiency has been compared with two widely-used commercial adsorbents. The results indicated that the virgin NMP material has no adsorption capacity, while the application of an activation stage to modify the NMP process has a significant effect on its porosity and thus adsorption capacity. The Cu and Pb removal capacity of the activated sample (A-NMP) at a pH level of 4 was 3mmol and 3.4mmol per gram of the adsorbent, respectively, which was considerably higher than the commercial ones. [Copyright &y& Elsevier]

• A review on sources and composition of sewage sludge for pyrolysis. • Thermal degradation studies and behavior of sewage sludge using TGA. • Review of mechanism and principles of pyrolysis process for sewage sludge. • Comprehensive discussion on the selection of kinetic models for scale up. • Application of machine learning tool forprediction of kinetic data. Sewage sludge is a by-product of the wastewater treatment process, which has the potential to be a source of transport fuels, heat, and power using the pyrolysis process. Considering the prevalence and disposal issues associated with sewage sludge, the objective of this study is to critically review the recent advancements in sewage sludge pyrolysis and its kinetics obtained using the thermogravimetric techniques, and other associated different kinetic models documented in the literature. The study will identify optimum operating conditions and design parameters to obtain high yields. The state-of-the-art perspectives and the challenges associated with full-scale implementation are highlighted for biofuels and resource recovery from the sewage sludge. Furthermore, machine-learning approaches in thermal kinetics of pyrolysis are presented and discussed in terms of their effectiveness in predicting thermal kinetics data. Finally, the challenges for a successful implementation and commercial viability of sewage sludge pyrolysis are discussed. [ABSTRACT FROM AUTHOR]

In the present study the evaluation of Direct Red 89 (DR89) dye removal from synthetic wastewater by a lab-scale hydrodynamic cavitation (HC) process has been investigated under different operational conditions; the influence of co-existing cations and anions was applied using synthetic wastewater to assess whether the DR89 removal was enhanced. To study the effect of operational parameters, an empirical approach was adopted for the modeling of the HC process. The results showed that the DR89 degradation rate was strongly influenced by solution pH, reaction time and initial DR89 concentration. The removal efficiencies of DR89 were enhanced remarkably with the reaction time increment. When the initial concentration of DR89 increased from 30 to 90 mg/L, the DR89 removal efficiency decreased from 36.3 ± 3.8% to 17.5 ± 2.5%. In addition, the highest DR89 removal efficiency (75.4 ± 3.4%) was observed at a solution pH of 3. At a solution pH of 8, the DR89 removal efficiency was 18.4 ± 1.1%. An initial DR89 concentration of 80 mg/L was 75.4 ± 5.1% degraded after 130 min at a solution pH of 3. The results indicated that a synergistic effect occurred due to the added ions except for HCO 3 –. The removal of DR89 by the HC process was extremely enhanced with NO 3 ‾ ions with synergetic index higher than 2.5. Kinetic studies revealed that the decolorization of DR89 by HC followed a first order kinetic mechanism. The comparison between the predicted results of the empirical model and experimental data was also conducted. The empirical model described the DR89 removal efficiency under different conditions (R2 : 0.93) and the results showed the HC reaction to be a useful technology for the treatment of dye in the textile wastewater. [ABSTRACT FROM AUTHOR]