Wastewater Treatment Technologies Research Articles

Bibliometric analysis of research trends in biogranulation technology for wastewater treatment.

Inadequate management and treatment of wastewater pose significant threats, including environmental pollution, degradation of water quality, depletion of global water resources, and detrimental effects on human well-being. Biogranulation technology has gained increasing traction for treating both domestic and industrial wastewater, garnering interest from researchers and industrial stakeholders alike. However, the literature lacks comprehensive bibliometric analyses that examine and illuminate research hotspots and trends in this field. This study aims to elucidate the global research trajectory of scientific output in biogranulation technology from 1992 to 2022. Utilizing data from the Scopus database, we conducted an extensive analysis, employing VOSviewer and the R-studio package to visualize and map connections and collaborations among authors, countries, and keywords. Our analysis revealed a total of 1703 journal articles published in English. Notably, China emerged as the leading country, Jin Rencun as the foremost author, Bioresource Technology as the dominant journal, and Environmental Science as the prominent subject area, with the Harbin Institute of Technology leading in institutional contributions. The most prominent author keyword identified through VOSviewer analysis was "aerobic granular sludge," with "sequencing batch reactor" emerging as the dominant research term. Furthermore, our examination using R Studio highlighted "wastewater treatment" and "sewage" as notable research terms within the field. These findings underscore a diverse research landscape encompassing fundamental aspects of granule formation, reactor design, and practical applications. This study offers valuable insights into biogranulation potential for efficient wastewater treatment and environmental remediation, contributing to a sustainable and cleaner future.

Chitosan-based modalities with multifunctional attributes for adsorptive mitigation of hazardous metal contaminants from wastewater

The increase in population and industrialization has intensified water scarcity and stress, and contaminated water bodies. Therefore, the development of advanced water and wastewater treatment technologies has gained global attention from researchers. Adsorption, using natural materials (nano, polymer, and bio) is one of the most cost-effective, less challenging, and well-known technologies for wastewater treatment and improving water quality. Among them, chitosan (CS) has demonstrated a set of unique features, such as biodegradability, eco-friendliness, availability, low cost, and biocompatibility. Hence, this review provides an overview of some recent advancements in the removal of heavy metals, including As (III) and (V), Cd (II), Cu (II), Cr (VI), and Pb (II) by CS-based adsorbents, and their potential effects on human health. It also covers the synthesis of CS-based adsorbents for the elimination of mentioned contaminants in recently reported studies. In addition, this study recommends encountering potential drawbacks by enhancing the adsorption capacity by incorporating functional groups, nanoparticles, and other materials. These modifications may help increase selectivity for specific metal contaminants and synthesize adsorbents that can perform better over a wide range of pH. Insights gained from this study will guide researchers in the future toward optimal water treatment and pollutant elimination strategies.

Coating seeds with purified-hydrocolloids extracted from conventional activated sludge affects the growth physiology of wheat under gradient salt stress

With continuous innovations in wastewater treatment technology, the use of excess sludge has become a research focus. Purified-hydrocolloids obtained from aerobic granular sludge (AGS) and conventional activated sludge (CAS) have many practical applications, including waterproofing, adsorption, flame retardance, slow-release properties, and seed coating. In this study, purified-hydrocolloids extracted from CAS was used as a new seed coating, which was uniformly sprayed onto the surface of wheat seeds. Purified-hydrocolloids was most effective in resisting salt stress in wheat seedlings at a NaCl concentration of 125mmol/L (soil salinity 2.74g/Kg). The germination percentage, plant height, K+/Na+ ratio, soluble sugar and soluble protein contents of purified-hydrocolloids-coated seeds increased by 13.33%, 46.32%, 37.25%, 8.89%, and 36.22%, respectively, compared with wheat seeds without purified-hydrocolloids coating. Inhibition of O2− production activity and malondialdehyde content was reduced by 38.62% and 48.00%, respectively. Therefore, the purified-hydrocolloids coating had a mitigating effect on wheat seed germination and seedling growth in salt-stressed environments, and this application would be beneficial to the use of saline soil resources and the improvement of ecosystems in coastal areas.

Innovative potassium hexacyanoferrate intercalated into layered double hydroxide adsorbent for efficient cesium removal from seawater

Effective radioactive wastewater treatment technology is essential to ensure the sustainable development of nuclear energy. Here, the potassium ferrocyanide (HCF) intercalating with layered double hydroxide (LDH) (HCF@LDH) was successfully synthesized by coprecipitation method for selective cesium (Cs) removal from seawater. Characteristics of the adsorbent, and adsorption performance under different environmental conditions including Cs+ ion selectivity, and underlying adsorption mechanism were systematically investigated. The experimental results demonstrated that the adsorption capacity of HCF@LDH was 52.08 mg/g and it effectively removed 100 % of Cs+ from up to 200 mg/L Cs solution within 1 h under an optimal pH of 6.0–10.0. Moreover, the adsorbent displayed high selectivity towards Cs+ even in seawater and more than 90 % of Cs+ was removed from seawater and the highest cesium removal capacity from seawater was 44.64 mg/g. Both the Langmuir isotherm model (R2 = 0.997) and the pseudo-second-order kinetic model (R2 = 0.999) provided a good fit for the adsorption data signifying the adsorption process is homogeneous and formed monolayer through chemisorption. Furthermore, the reusability analysis exhibited this adsorbent was recycled and reused for at least 5 cycles without losing its original adsorption performance. The physicochemical analysis of the HCF@LDH proved that K4Fe (CN)6 successfully intercalated onto LDH and cation exchange between K+ and Cs+ played an important role in effective Cs adsorption. More specifically, the interstitial spaces of the hexacyanoferrate crystals facilitate the cation exchange process. The findings of this study demonstrate that HCF@LDH is a unique, highly effective, and selective adsorbent for Cs+ from complex seawater.

Biofilm Reactors: A Potential Alternative to Current Treatment Technology for Wastewater in Kathmandu Valley

Kathmandu Valley faces challenges managing its growing wastewater volume, compounded by the complex composition of unregulated industrial discharges. Releasing untreated wastewater poses a severe risk to public health and the environment. Existing wastewater treatment infrastructure, primarily reliant on conventional activated sludge processes (ASP) struggles to meet growing demands. These systems require substantial land area, are sensitive to influent variations, produce a high volume of sludge, and incur high operational and maintenance costs. Biofilms, naturally occurring assemblages of microorganisms adherent to surfaces and embedded within an extracellular polymeric matrix (EPS), present a compelling alternative for wastewater treatment due to their diverse pollutant removal capabilities. When implemented as biofilm reactors, they offer distinct advantages, including tolerance to fluctuations in wastewater composition, minimal land requirements, and reduced energy consumption. Notably, microbes residing within a biofilm are capable of biodegradation of persistent materials such as pharmaceuticals, metals, and plastics. Globally, biofilmmediated wastewater treatment has been implemented successfully, while a knowledge gap remains for the treatment of Kathmandu's wastewater. This review critically assesses biological wastewater treatment methods, providing insight into: a) suspended growth process with their configuration, application, and limitations, b) wastewater treatment infrastructures of Kathmandu Valley, and c) biofilm process with their configuration, factors influencing biofilm development and performance, application of specific microbial strains for enhanced treatment efficiency, and factors to be considered during implementation. Furthermore, the paper recommends: a) an extensive study of laboratory-scale biofilm reactors evaluating and optimizing their performance for local integration and b) investigating the role of diverse microbial communities to further enhance the treatment plant's operation. By prioritizing research and development towards biofilm technology, Kathmandu Valley can achieve efficient and environmentally friendly wastewater management.

Evaluating The Effectiveness of Wastewater Treatment In the Reusable Packaging Industry: A Case Study of ALNER’S WWTP In Indonesia

The widespread use of single-use plastic packaging has become a significant environmental issue, particularly in the Global South. This study examines the innovative approach of the startup Alner, which employs a combination of electrochemical treatment and Moving Bed Biofilm Reactor (MBBR) technology in its wastewater treatment plant (WWTP) to manage wastewater generated from the cleaning of reusable packaging. Wastewater samples were collected before and after treatment, and analyzed for key parameters such as Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5), Total Suspended Solids (TSS), oil and grease, ammonia, surfactants, and phosphates. The results demonstrated a significant reduction in all measured pollutants, with COD reduced by 99.58% and BOD5 by 99.56%. Post-treatment values for all parameters were well within the regulatory limits set by the Ministry of Environment and Forestry Regulation No. P68/MenLHK/Setjen/Kum.1/8/2016. This study underscores the potential of reuse models in reducing single-use plastic waste and highlights the importance of effective wastewater treatment in maintaining environmental sustainability. Alner's approach provides a scalable and environmentally friendly solution, setting a benchmark for similar initiatives in the industry, and supports the feasibility and sustainability of integrating advanced wastewater treatment technologies in the reusable packaging sector, offering a comprehensive solution to plastic pollution.

Fast development of purple nonsulfur bacteria (PNSB) in a bubble column photobioreactor: Influence of carbon source and dissolved O2 availability on wastewater treatment performance

Photobioreactors with purple nonsulfur bacteria (PNSB) constitute a promising technology for wastewater treatment, gas purification, and high value-added bioproducts. In this work, different operational strategies were tested to investigate their impacts on photobioreactor performance, biomass properties, and microbial community. It showed that the operational conditions significantly influence the performance and microbial composition of PNSB photobioreactors. Anaerobic conditions favored the dominance of Rhodopseudomonas spp. and moderate COD removal efficiency (36.7 %), while aerobic conditions significantly enhanced COD removal efficiency (91.7 %) but altered the microbial community composition from PNSB to aerobic heterotrophic microorganisms, such as Delftia sp. and Microbacterium sp.. The removal ratio of chemical oxygen demand (COD):N:P was 100:10:2 under anaerobic conditions with continuous CO2 supply, while it was 100:1:1 under aerobic conditions with continuous supply of a CO2/O2 mixture. Net CO2 removal efficiencies of 2.8 % and 5.4 % were recorded under anaerobic conditions with and without the addition of organic carbon, respectively. The outlet CO2 concentration showed that CO2 uptake occurred under dark and anaerobic conditions without organic carbon. The reduced production of extracellular polymeric substances (EPS) was observed after COD was removed from the influent, preventing granule formation.

Assessment of Compliance of LBR Technology for Wastewater Treatment of Centralized Discharge Systems in Settlements with the Reference Requirements

The paper considers the method for cleaning the municipal wastewater using LBR-technology (Laminar Biofilm Reactor) implemented by RDIEI with patented improvements to analogues. An assessment was made of the technology compliance with the requirements of the best available technologies set out in the information and technical reference book ITS 10-2015 "Wastewater treatment using centralized sewerage systems for settlements and urban districts".

Carbon footprint analysis of wastewater treatment processes coupled with sludge in situ reduction

The goal of this study was to assess the impacts or benefits of sludge in situ reduction (SIR) within wastewater treatment processes with relation to global warming potential in wastewater treatment plants, with a comprehensive consideration of wastewater and sludge treatment. The anaerobic side-stream reactor (ASSR) and the sludge process reduction activated sludge (SPRAS), two typical SIR technologies, were used to compare the carbon footprint analysis results with the conventional anaerobic - anoxic - oxic (AAO) process. Compared to the AAO, the ASSR with a typical sludge reduction efficiency (SRE) of 30 % increased greenhouse gas (GHG) emissions by 1.1 - 1.7 %, while the SPRAS with a SRE of 74 % reduced GHG emissions by 12.3 - 17.6 %. Electricity consumption (0.025 - 0.027 kg CO2-eq/m3), CO2 emissions (0.016 - 0.059 kg CO2-eq/m3), and N2O emissions (0.009 - 0.023 kg CO2-eq/m3) for the removal of secondary substrates released from sludge decay in the SIR processes were the major contributor to the increased GHG emissions from the wastewater treatment system. By lowering sludge production and the organic matter content in the sludge, the SIR processes significantly decreased the carbon footprints associated with sludge treatment and disposal. The threshold SREs of the ASSR for GHG reduction were 27.7 % and 34.6 % for the advanced dewatering - sanitary landfill and conventional dewatering - drying-incinerating routes, respectively. Overall, the SPRAS process could be considered as a cost-effective and sustainable low-carbon SIR technology for wastewater treatment.

Microwave Radiation in Wastewater Treatment and Sedimentations Treatment Technologies

The main results of research on the use of microwave radiation in wastewater treatment and treatment of their sedimentations, as well as water treatment waste, are presented. The thermal influence of microwaves on the water and sedimentations properties is considered. The experimental data obtained by foreign and domestic specialists for the following processes using microwaves are shown: degradation of organic substances, de-emulsification of oil-containing wastewater, removal of metals, disinfection, intensification of biogas yield, sediments pyrolysis, modification of the absorbents, intensification of compaction and dewatering of natural water treatment sedimentation. New microwave equipment for treatment the various wastes is described.

Emulsion liquid membrane (ELM) enhanced by nanoparticles and ionic liquid for extracting vanadium ions from wastewater.

Emulsion liquid membrane (ELM) stands out as an extraction process that has drawn much attention due to its promising prospects in industrial wastewater treatment technology. Nevertheless, the pivotal challenge is to reach high membrane stability to overcome the obstacle of applying ELM at the industrial scale. In this study, ELM was boosted by using nanoparticles (superparamagnetic iron oxide (Fe2O3)) in the stripping phase (W1) and ionic liquid (1-methyl-3-octyl-imidazolium-hexafluorophosphate [OMIM][PF6) in the oil phase (O) for recovering/extracting vanadium from synthetic wastewater to near completion and at the same time enhancing emulsion stability to be appropriate for industrial application. The vanadium recovery/extraction percentage has been raised significantly in 3min to 99.6% when adding 0.01% (w/w) Fe2O3 NPs (20 to 50nm in size) in the internal phase (W1) and 5% (v/v) [OMIM]PF6 ionic liquid in the oil phase (O). Also, the emulsion stability was considerably improved, and the leakage percentage was reduced to 16% after 3days. The results of this study could be used in the future to remove additional heavy metal ions from industrial effluents.

Na-Kenyaite as Efficient Basic Blue-41 Dye Removal: Synthesis and Regeneration Studies

Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially contaminated water using Na-kenyaite materials in batch mode. Firstly, Na-kenyaites were prepared by the hydrothermal process at a temperature of 150 to 170 °C for a period of 2 to 7 days using different silica sources and ratios of SiO2/NaOH/H2O. The prepared materials were characterized by different techniques such as XRD, FTIR, 29Si MAS NMR, TGA/DTA, SEM, and nitrogen adsorption isotherms. A pure Na-kenyaite phase was successfully obtained using a fumed silica source and 5SiO2/Na2O/122H2O ratio. The removal experiments of basic blue-41 estimated the effectiveness of Na-kenyaites in removing properties, investigating the influence of the solid dosage, initial basic blue-41 concentration, and solution pH or Na-kenyaite solid. Results showed optimal dye removal of around 99% at pH levels above 7. Furthermore, the estimated maximum removal capacity from the Langmuir isotherm was between 124 and 165 mg/g. The results demonstrated efficient removal by Na-kenyaites and its prominence for wastewater treatment. Finally, this study explored the regeneration and reuse of Na-kenyaites through seven cycles and reported a design of a batch adsorber system to reduce the initial concentration of 200 mg/L at different percentages.

Study on the treatment of oil production wastewater by corona discharge coupling Fenton reagent

As the main by-product of oil production, oil production wastewater has the characteristics of high organic content and poor biodegradability, which makes the low temperature plasma wastewater treatment technology get new development. The Ground electrode atomization negative corona discharge（GEANCD） technology increases the discharge current on the basis of traditional corona discharge, but the uneven atomization of liquid is a key challenge at present, which will have a great impact on the degradation of wastewater pollutants. In this study, the GEANCD reactor was redesigned and a self-developed spiral wire hole electrode (SWHE) was used to replace the conventional wire electrode (WE). The discharge characteristics of the reactor under the two electrode structures were investigated and the optimal discharge parameters were determined. Under the optimum discharge parameters, the treatment effect of the two electrode structures with or without coupling Fenton reagent on oil production wastewater was also compared. The experimental results show that under the optimal discharge parameters of flow rate of 25 mL/min, plate electrode distance of 50 mm and discharge voltage of 14 kV, the reactor equipped with SWHE has higher discharge current, and the treatment effect of oil production wastewater is better when coupled with Fenton reagent.

Characterization and application of LDH with chitosan composites investigated by positron annihilation lifetime spectroscopy and surface texture for the adsorption of methyl orange

With a rapid increase in industrial growth around the world, the demand for an entirely novel category of nanoparticles and technologies for wastewater treatment has become a key concern for environmental protection. Recently, hybrids of layered double hydroxides (LDH), particularly those containing LDH, have gained attention as potential nanoscale adsorbents for water treatment. Recent research has shown that LDH-containing composites are interesting versatile materials with the ability to be used in energy storage, photocatalysis, nanocomposites, and water treatment. In the current work, LDH-containing composites were utilized as adsorbents for the purpose of purifying water. The adsorbents investigated are Zn–Co–Fe/LDH/Chitosan-in situ sample preparation (LDH/CS1) and Zn–Co–Fe/LDH/Chitosan-ex situ sample preparation (LDH/CS2). Furthermore, LDH/CS1 and LDH/CS2 were investigated for wastewater treatment from methyl orange dye (MO) with various adsorption conditions. When the initial MO concentration was 20 mg/L and the amount of adsorbent was 0.1 g, the removal efficiency reached 72.8 and 91.7% for LDH/CS1 and LDH/CS2, respectively. The MO’s maximum adsorption capabilities are 160.78 and 165.89 mg/g for LDH/CS1 and LDH/CS2, respectively, which is much greater than that of comparable commercial adsorbents. MO adsorption onto LDH/CS1 and LDH/CS2 was best characterized by the pseudo-second-order kinetic model. The equilibrium adsorption data was followed by the Freundlich and Langmuir models. The adsorption is favorable as evidenced by the equilibrium parameter RL values for MO adsorption onto LDH/CS1 and LDH/CS2, which were 0.227 and 0.144, respectively. Using the free volume distribution method and the positron annihilation lifetime technique, the nanostructure of the materials was examined.

Crystal phase-driven performance of MnO2 in aqueous phase low-temperature thermal catalysis: Synergistic interactions between Mn3+ and surface lattice oxygen

Catalytic oxidation at mild conditions is crucial for mitigating the high pressure and high temperature challenges associated with current catalytic wet air oxidation (CWAO) technologies in wastewater treatment. Among potential materials for catalytic oxidation reactions, polycrystalline MnO2 existed in natural minerals holds considerable promise. However, the relationships between different crystal phases of MnO2 and their catalytic activity sources in aqueous phase remain uncertain and subject to debate. In this research, we synthesized various MnO2 crystal phases, comprising α-, β-, δ-, γ-, ε-, and λ-MnO2, and assessed their catalytic oxidation efficiency during low-temperature heating for treatment of organic pollutants. Our findings demonstrate that λ-MnO2 exhibits the highest catalytic activity, followed by δ-MnO2, γ-MnO2, α-MnO2, ε-MnO2, and β-MnO2. The variations in catalytic activity among different MnO2 are attributed to variances in their oxygen vacancy abundance and redox activity. Furthermore, we identified the primary active species, which include Mn3+ and superoxide radicals (•O2–) generated by surface lattice oxygen of MnO2. This research highlights the critical role of crystal phases in influencing oxygen vacancy content, redox activity, and overall catalytic performance, providing valuable insights for the rational design of MnO2 catalysts tailored for effective organic pollutant degradation in CWAO applications.

Novel insights into the biological state in algal-bacterial granular sludge granulation: Armor-like protection provided by the algal barrier

Algal-bacterial granular sludge (ABGS) composed of microalgae and aerobic granular sludge, is a sustainable and promising technology for wastewater treatment. However, the formation mechanism of ABGS has not been clearly defined, and the direct formation of ABGS in saline wastewater has rarely been investigated. This study proposed novel insights into the granulation process of ABGS by assembling the algal barrier, which was successfully cultivated directly in saline wastewater. The results concluded that ABGS with the algal barrier maintained a higher biomass (MLSS of 7046 ± 61 mg/L), larger particle sizes (1.21 ± 0.06 mm), and better settleability (SVI30 of 46 ± 1 mL/g), enabling efficient pollutants removal. Soluble microbial products (SMP) were found to be closely related to the emergence of the algal barrier. In addition, under salinity stress, the high production of extracellular polymeric substances (EPS, 133.70 ± 1.40 mg/g VSS), specifically TB-EPS (90.29 ± 1.12 mg/g VSS), maintained a crucial role in the formation of ABGS. Further analysis indicated that biofilm producing bacteria Pseudofulvimonas and filamentous eukaryote Streptophyta were the key players in ABGS formation with the algal barrier. Furthermore, the enhancement of key genes and enzymes involved in nitrogen metabolism, TCA cycle, and polysaccharide metabolism suggested a more robust protective effect provided by the algal barrier. This study is expected to advance the application of simultaneous ABGS formation and pollutant removal in wastewater.

Investigations of nanomaterial-based membranes for efficient removal of contaminants from wastewater via membrane distillation: a critical review

The requirement for wastewater treatment is paramount in ensuring environmental sustainability and safeguarding public health. As industrialization and urbanization accelerate, the volume of wastewater generated continues to increase, containing a diverse range of pollutants and contaminants. Untreated wastewater poses serious threats to ecosystems, water bodies, and human communities, leading to pollution, waterborne diseases, and ecological imbalances. Effective wastewater treatment becomes essential to mitigate these adverse effects by removing or reducing pollutants before discharge into natural water sources. This process helps to preserve water quality, protect aquatic life, and maintain the overall health of ecosystems. Membrane distillation (MD) has emerged as a promising technology for wastewater treatment, offering an innovative approach to address the challenges associated with conventional treatment methods. In MD, a hydrophobic membrane serves as a selective barrier, allowing water vapor to pass through while preventing the passage of contaminants. This paper offers an extensive overview of the latest advancements in nanotechnology and membrane distillation applied in wastewater treatment. We will delve into different types of nanomaterials that have been used to enhance the properties of MD membranes, such as nanocomposites, nanoparticles, and nanofiber membranes. We also explore the mechanisms by which these nanomaterials improve the separation efficiency, anti-fouling properties, and durability of MD membranes. Additionally, we highlight the potential of hybrid membranes that combine different types of nanomaterials for further improving the performance of MD in wastewater treatment. We provide examples of recent studies that have investigated the use of hybrid membranes, including carbon nanotube-graphene oxide hybrid membranes, nanocomposite nanofiber membranes, and silver nanoparticle-embedded membranes. We also identify some areas for future research and development, such as the scale-up and commercialization of nanotechnology-based MD systems. In summary, this review paper highlights the potential of nanotechnology to enhance the performance of MD in wastewater treatment, leading to improved water quality and a cleaner environment.

Self-regulation strategy of influent dissolved oxygen in ANAMMOX unit of domestic wastewater onsite source-separation and synergistic treatment process

An onsite source-separation and synergistic treatment (O3ST) process has been proposed in a previous study. In the study, it was found that toilet wastewater is characterized by spontaneously realizing and stably maintaining a partial nitritation (PN) without dissolved oxygen (DO) control. On this basis, to realize the goal of practical application of ANAMMOX technology following the PN in the O3ST process, this paper carries out the key research on the self-regulation strategy of DO in the effluent of PN unit to reduce the influent DO of ANAMMOX unit. By adding a buffer unit between the PN and ANAMMOX unit with an effective volume of 50.0 % of the PN unit, an interconnecting area of 0.9 % of the coplanar area of the PN and buffer unit, an overflow length of 35.7 % of the width of the PN unit, the automatic control to reduce the amount of DO diffusion and residual in the buffer unit was realized, and the DO concentration of the influent from the buffer to ANAMMOX unit was guaranteed to be less than 1.00 mg/L. Successful application of ANAMMOX technology can increase the TN removal efficiency of the process from a bottleneck value of 66.0 % to 84.0 %, with 44.0 % of the TN removal occurring in the ANAMMOX unit. This study is expected to apply the ANAMMOX technology in a low-maintenance or even no-maintenance form in the O3ST process, which is both an expansion of the application scope of the ANAMMOX technology and a breakthrough in decentralized wastewater treatment technology.

Phosphorous speciation in EPS extracted from Aerobic Granular Sludge

Wastewater treatment technologies opened the door for recovery of extracellular polymeric substances (EPS), presenting novel opportunities for use across diverse industrial sectors. Earlier studies showed that a significant amount of phosphorus (P) is recovered within extracted EPS. P recovered within the extracted EPS is an intrinsic part of the recovered material that potentially influences its properties. Understanding the P speciation in extracted EPS lays the foundation for leveraging the incorporated P in EPS to manipulate its properties and industrial applications. This study evaluated P speciation in EPS extracted from aerobic granular sludge (AGS). A fractionation lab protocol was established to consistently distinguish P species in extracted EPS liquid phase and polymer chains. 31P nuclear magnetic resonance (NMR) spectroscopy was used as a complementary technique to provide additional information on P speciation and track changes in P species during the EPS extraction process. Findings showed the dominance of organic phosphorus and orthophosphates within EPS, besides other minor fractions. On average, 25% orthophosphates in the polymer liquid phase, 52% organic phosphorus (equal ratio of mono and diesters) covalently bound to the polymer chains, 16% non-apatite inorganic phosphorus (NAIP) precipitates mainly FeP and AlP, and 7% pyrophosphates (6% in the liquid phase and 1% attached to the polymer chains) were identified. Polyphosphates were detected in initial AGS but hydrolyzed to orthophosphates, pyrophosphates, and possibly organic P (forming new esters) during the EPS extraction process. The knowledge created in this study is a step towards the goal of EPS engineering, manipulating P chemistry along the extraction process and enriching certain P species in EPS based on target properties and industrial applications.

Advanced Treatment Technologies for Pollutants Removal in Wastewater

Conventional wastewater treatment technologies have been extensively studied for degrading organic matter, suspended solids, nutrient removal, and lowering microbial loads. They produce acceptable-quality effluent, but researchers have reported several limitations. Recently, advanced wastewater treatment technologies have preceded as an alternative to the degradation of recalcitrant wastes such as persistent organic compounds (POPs), pharmaceutically active compounds (PhACs), contaminants of emerging concern (CECs), and heavy metals (H.M). They can be physical, chemical, biological, or integration between one or more technologies. This is to meet the requirements for reuse for different purposes, minimize or prevent the negative impacts on the environment, and create new untraditional water resources to solve the water shortage problem. This article is a collected review of advanced wastewater treatment technologies. Also, the applications of these technologies with special concern for partially/hardly degradable pollutants from wastewater are indicated. They are eco-friendly, cost-effective, low-energy systems with a small footprint. Their selection depends on the characterization of wastewater, biodegradability, available footprint, quality of treated effluent required, cost, availability of funds, and personal skills.