Way For Wastewater Treatment Research Articles

Potential application of 2D nano-layered MXene in analysing and remediating endocrine disruptor compounds and heavy metals in water.

With the advancement of technologies and growth of the economy, it is inevitable that more complex processes are deployed, producing more heterogeneous wastewater that comes from biomedical, biochemical and various biotechnological industries. While the conventional way of wastewater treatment could effectively reduce the chemical oxygen demand, pH and turbidity of wastewater, trace pollutants, specifically the endocrine disruptor compounds (EDCs) that exist in µgL-1 or ngL-1 have further hardened the detection and removal of these biochemical pollutants. Even in small amounts, EDC could interfere human's hormone, causing severe implications on human body. Hence, this review elucidates the recent insights regarding the effectiveness of an advanced 2D material based on titanium carbide (Ti3C2Tx), also known as MXene, in detecting and removing EDCs. MXene's highly tunable feature also allows its surface chemistry to be adjusted by adding chemicals with different functional groups to adsorb different kinds of EDCs for biochemical pollution mitigation. At the same time, the incorporation of MXene into sample matrices also further eases the analysis of trace pollutants down to ng L-1 levels, thereby making way for a more cleaner and comprehensive wastewater treatment. In that sense, this review also highlights the progress in synthesizing MXene from the conventional method to the more modern approaches, together with their respective key parameters. To further understand and attest to the efficacy of MXene, the limitations and current gaps of this potential agent are also accentuated, targeting to seek resolutions for a more sustainable application.

Efficient persulfate activation by photo-excited organic dyes: Mechanism and application for actual dyeing wastewater self-purification

Sulfate Radical-Advanced Oxidation Processes are considered an efficient way for purifying dyeing wastewater, which commonly resists conventional treatment processes owing to the complex components, low biodegradability and high toxicity. However, this emerging technique is associated with issues of secondary pollution and great energy consumption during peroxymonosulfate (PMS) or persulfate (PS) activation processes. Herein, a dye pollutant/PS/visible light self-catalytic system was constructed, based on the photosensitive property of organic dyes for PS activation without catalyst and energy input. In this system, the degradation ratio of 100 mL 10 mg L−1 basic fuchsin, rhodamine B and eosin Y significantly increased by 60%, 76% and 50%, compared with the process without light irradiation. Such improvements were attributable to an efficient photo-induced electron transfer from photo-excited dyes to PS, which has the precondition that the lowest unoccupied molecular orbital (LUMO) energy level of the dye is higher than that of PS, thereby generating oxidizing species like ·SO4−, ·OH and 1O2 for pollutants degradation. Due to the high performance of pollutants simultaneous removal, wide pH adaptability and anti-interference, the complex self-catalytic system consisted of nine dyes and bis-phenol A exhibited the possibility for practical application. Expectedly, the actual dyeing wastewater self-purification system featured a decolorization efficiency of 54% accompanied by the removal of co-existing aromatic proteins and tryptophan-like substances; moreover, the acute bio-toxicity of the raw wastewater greatly decreased by 61.6%. Owing to its high efficiency, eco-friendliness and low consumption, the constructed “using waste to treat waste” system provides a promising way for wastewater treatment.

Biological treatment solutions using bioreactors for environmental contaminants from industrial waste water

AbstractHuman needs have led to the development of various products which are produced in the industries. These industries in turn have become a source of various environmental concerns. As industries release regulated and unregulated contaminants into the water bodies, it has become a serious concern for all living organisms. Various emerging contaminates from industries like pesticides, pharmaceuticals drugs like hormones, antibiotics, dyes, etc., along with byproducts and new complexes contaminate the water bodies. Numerous traditional approaches have been utilized for the treatment of these pollutants; however, these technologies are not efficient in most cases as the contaminants are mixed with complex structures or as new substances. Advanced technologies such as bioreactor techniques, advanced oxidation processes, and so on have been used for the treatment of industrial wastewater and have served as an alternative way for wastewater treatment. Overall, biological treatment techniques based on bioreactors provide a long-term and ecologically useful solution to industrial wastewater contamination. They play an important role in saving water resources and encouraging a greener sustainable future for mankind. The current review outlines the industrial effluents that are released into water bodies, contaminating them, as well as the numerous traditional and novel treatment procedures used for industrial wastewater treatment. Graphical abstract

Industrial wastewater treatment methods employed in Southeast Asian countries

Wastewater pollution from industrial sector has tremendously increased in recent years and has posed severe environmental and health problems in many countries worldwide. Humans and other living organisms need clean water to sustain life and performing other daily activities, such as growing crops in agriculture, mining, and manufacturing. However, lack of effective water treatment and poor management of water sources caused by wastewater discharge to the environment without sufficient treatment have contributed to the high concentration of organic matter and hazardous compounds. In Southeast Asian countries, several treatments are employed in treating wastewater such adsorption, advanced oxidation process and membrane filtration reactor. As there are limited data demonstrating the most efficient and cost-effective way for wastewater treatment in the Southeast Asia’s industrial sector, this paper aims to examine the existing and advanced methods for treating industrial wastewater in Southeast Asian countries and assess its efficacy in removing contaminants from the industrial wastewater. PRISMA approach was used to conduct the review of this study with 64 articles making the final selection from 5 Southeast Asian countries (Malaysia, Singapore, Indonesia, Thailand and Vietnam). The review found that the anaerobic aerobic-wetland sequential system and a convective sludge dryer removed the highest number of contaminants eliminating almost 99% of chemical oxygen demand (COD), volatile suspended solid (VSS), and volatile fatty acid (VFA) with an added benefit of being cost effective, environmentally friendly and sustainable.

Hg2+ removal from wastewater by anchoring nitrogen/sulfur active center onto metal-organic framework via Schiff-base reaction: Synthesis, characterization, and experiment

Remediation of Hg2+ pollution in wastewater is imminent. Herein, a Metal-Organic Framework hybrid Uio-DBD-x was designed and synthesized via rational introducing the 5-Diamino-1,4-benzenedithiol Dihydrochloride (DBD) molecule onto parent Uio-66-NH2. By optimizing the synthesis conditions, the material exhibited better adsorption performance when x = 1. The characteristics including crystallinity, morphology, and pore size were analyzed. 12.64 nm for pore diameter and 493.73 m2/g for surface areas of Uio-DBD-1 were obtained. Subsequently, the adsorption performance of Uio-DBD-1 towards Hg2+ was studied under different pH, dosage, concentration, and time. The corresponding maximum adsorption capacity of 423.10 mg/g and equilibrium time of 10 min was achieved. Remarkably, Hg2+ concentration could be reduced below the emission limit (0.05 mg/L). Furthermore, the selectivity and reusability of the adsorbent were investigated, and the results manifested that Uio-DBD-1 maintains high removal efficiency (82.10%) after 6 times recycles. The possible adsorption mechanism could be ascribed to the strong interaction (chelation, proton exchange, and coordination) between Hg2+ and –NH2/-SH groups. This work breaks new ground in functional material design and paves the way for wastewater treatment.

Temperature-swing adsorption of 4-isopropylphenol and bisphenol A onto a poly(N-isopropylacrylamide)/silica gel composite

Poly( N -isopropylacrylamide) (poly(NIPA)) is a thermosensitive polymer, with a lower critical solution temperature (LCST) of ~33 °C in water. Herein, a poly(NIPA)/silica gel composite was developed as an adsorbent for the temperature-swing adsorption (TSA) of organic pollutants in aqueous media. Poly(NIPA) was grafted onto a millimeter-sized silica gel by silane coupling, followed by free radical polymerization. The composite reversibly adsorbed/desorbed organic pollutants such as bisphenol A and 4-isopropylphenol by changing the temperature across the LCST range to modulate the hydrophilicity/hydrophobicity of poly(NIPA). The adsorption isotherms and kinetics were evaluated through a batch experiment. A continuous TSA process using a fixed-bed column with adsorption at 40 °C followed by desorption at 20 °C was demonstrated. The associated breakthrough curve was predicted by a mathematical analysis involving the Henry constant and effective diffusivity. The composite overcomes drawbacks such as a low mechanical strength and thermosensitive volume change of conventional poly(NIPA) gels. Thus, this study provides a strategy for preparing an environmentally friendly adsorbent and designing an adsorption process for wastewater treatment and conservation of water environments. • A thermosensitive poly( N -isopropylacrylamide)/silica gel composite was developed. • The composite adsorbed/desorbed organic pollutants with a change in temperature. • The adsorption isotherms and kinetics were investigated. • A continuous temperature-swing adsorption process was demonstrated and designed. • It is an environment-friendly way for wastewater treatment and water conservation.

Experimental investigation of hydrodynamic cavitation of single and multiple hole orifice for wastewater treatment

In present scenario, fluid dynamics is widely used in industries in order to simplify industrial processes like to enhance chemical reactions, mineralization bio-refractory materials. Hydrodynamic cavitation is one of the fluid dynamic phenomena in which vapor filled cavities are formed and gets collapsed within fraction of seconds; used in textile industries for wastewater treatment. To find out effectiveness of hydrodynamic cavitation experimentation is done. In experimentation, a closed system is used with which hydrodynamic cavitation is studied using single and multi-hole orifice plates having different geometries and cross section areas are tested under different flowrates. Flow rates and cavitation are controlled by the application of a bypass line in system in order to find the best possible geometry of orifice that can give a higher cavitation effect. Orifice plate with multi hole is used to analyze the cavitation and its effect on waste water treatment. This experimentation provides an approach towards convenient way of wastewater treatment, preferably for textile industry.

Nanosheet-MoO3/Ti Porous Membrane Electrode for Dye Wastewater Treatment

Membrane coupling with electrochemical processes has proven to be an effective way for wastewater treatment. However, it still suffering from high energy consumption and low operational stability. Three different forms nanosheet-MoO3 were prepared by hydrothermal synthesis method via adjusting various additives to ammonium heptamolibdate. MoO3 loaded porous Ti membranes was employed as anode to constitute fixed-bed electrocatalytic reactor (FBER) for synthetic dye wastewater treatment to overcome the drawback of three different forms. The electrochemical properties of MoO3/Ti membranes were investigated, results showed that the MoO3/Ti membranes with hexadecyltrimethylammonium bromide (CTAB) additive exhibited the best electrochemical performance. Meanwhile, three MoO3/Ti membranes were used to constitute FBER for 100 mg l−1 MO wastewater treatment, the MO and COD removal rate of MoO3/Ti without additive, MoO3/Ti with CrCl3 additive and MoO3/Ti with CTAB additive were 78.6% and 65.3%, 83.2% and 72.9%, 90.3% and 81.6%, respectively. Furthermore, the energy consumption of MoO3/Ti with CTAB additive was only 0.76 kWh·kg−1·COD. After 3 repeated stabilities experiment of 12 h MO wastewater treatment, the removal rate of MO and COD remained above 97.2% and 88.6%. In sum, the FBER exhibits a great potential in the dye wastewater treatment with high efficiency and excellent stability.

Fluorescent hydrogels based on oxidized carboxymethyl cellulose with excellent adsorption and sensing abilities for Ag+

Heavy metal contamination in water and soil are harmful and destructive to the environment, it has always been regarded as a big problem. Herein, we developed a self-healing fluorescent hydrogel based on oxidized carboxymethyl cellulose with excellent sensing and adsorption abilities for Ag+. The detection and adsorption effects of hydrogels on heavy metal ions were studied. It turned out that the fluorescent hydrogel has sensitive detection and high adsorption capacity for Ag+, the detection limit was 3.798 μM, and the maximum adsorption capacity was 407 mg/g. The adsorption isotherm fitted the Langmuir model well, and the pseudo-secondary model for adsorption kinetics fitted well. The hydrogel could heal itself without external stimulus, it could be easily regenerated 7 times without loss of adsorption performance. In short, the prepared hydrogel has capability of self-healing, detecting and adsorbing heavy metal ions at the same time, good mechanical strength, these all made it a promising long-life adsorbent and provided a new way for wastewater treatment.

Developing a molecularly imprinted channels catalyst based on template effect for targeted removal of organic micropollutants from wastewaters

In this study, a novel catalyst with three-dimensional molecularly imprinted channels (3D-MICs) was proposed to preferentially remove the noxious organic micropollutants (OMPs) from wastewaters. The 3D-MICs catalysts exhibited robust selectivity (the imprinting factor reached above 2.04) and larger adsorption capacity (enhanced over 2.7 times), which was benefited from the synergy of template effect and size-exclusion effect. Compared with the original MOF-#/ persulfate (PS) system (40%), the SMX removal by MIC-#/PS system still retained over 91% in simulated wastewater, tap water, and polluted river water, respectively. With the spatial confinement, the degradation products by the MIC-#/PS system showed less quantity (4.6-fold) and lower toxicity than that by the original MOF-#/PS system. In-situ ATR-FTIR analysis and density functional theory (DFT) calculation revealed that the specific adsorption property for the targeted OMPs was mainly realized by the shape of the imprinted cavity, hydrogen bonds, hydrophobic-hydrophobic interaction, π-π stacking, and electrostatic interactions. Finally, the radical and non-radical pathways are involved in the MIC-#/PS system to ensure the high-efficiency removal of SMX. These insights revealed here could pave the way for wastewater treatment.

Multi-objective optimized pre-collection of sewage resources by sustainable enhanced coagulation process

Methods by which resources and energy in wastewater are recycled have been gaining popularity as promising and sustainable ways of wastewater treatment. Enhanced coagulation process (ECP) can effectively achieve resources recovery through its synergistic separation of particles, colloids, and dissolved substances. In this study, four significant parameters of ECP influencing simultaneous C, N and P recovery were obtained through the Plackett-Burman method: polyaluminium chloride (PACl), polyferric sulphate (PFS), powder-activated carbon (PAC), and zeolite. Considering the demanding connection between multivariate input and output parameters in practical engineering, their multi-objective parametric interaction and performance were investigated and optimized through the response surface method (RSM) on the basis of the varied values of retention efficiency. Specifically, PFS and PACl exhibited negative synergistic effects on soluble chemical oxygen demand (SCOD) recovery, while their interaction on the retention of total phosphorous (TP) and total nitrogen (TN) were not significant. Meanwhile, PAC and zeolite had positive synergistic effects on the retention of SCOD and on the TN recovery at high dosages, and revealed negative synergistic effects on the retention of TN at low dosages. However, their interaction on TP recovery was insignificant. According to obtained RSM model, the optimized parametric conditions were 20 mg L−1 of PACl, 136 mg L−1 of PFS, 50 mg L−1 of zeolite, and 236 mg L−1 of PAC, achieving the actual maximum values of 69.4%, 92.9% and 45.0% for the collaborative retention of SCOD, TP, and TN respectively. This suggests the promising performance of ECP in multi-objective pre-collection for fast integrated sewage resource recovery.

Molecularly Engineered Covalent Organic Frameworks for Hydrogen Peroxide Photosynthesis.

Synthesizing H2O2 from water and air via a photocatalytic approach is ideal for efficient production of this chemical at small‐scale. However, the poor activity and selectivity of the 2 e− water oxidation reaction (WOR) greatly restricts the efficiency of photocatalytic H2O2 production. Herein we prepare a bipyridine‐based covalent organic framework photocatalyst (denoted as COF‐TfpBpy) for H2O2 production from water and air. The solar‐to‐chemical conversion (SCC) efficiency at 298 K and 333 K is 0.57 % and 1.08 %, respectively, which are higher than the current reported highest value. The resulting H2O2 solution is capable of degrading pollutants. A mechanistic study revealed that the excellent photocatalytic activity of COF‐TfpBpy is due to the protonation of bipyridine monomer, which promotes the rate‐determining reaction (2 e− WOR) and then enhances Yeager‐type oxygen adsorption to accelerate 2 e− one‐step oxygen reduction. This work demonstrates, for the first time, the COF‐catalyzed photosynthesis of H2O2 from water and air; and paves the way for wastewater treatment using photocatalytic H2O2 solution.

Molecularly Engineered Covalent Organic Frameworks for Hydrogen Peroxide Photosynthesis

AbstractSynthesizing H2O2 from water and air via a photocatalytic approach is ideal for efficient production of this chemical at small‐scale. However, the poor activity and selectivity of the 2 e− water oxidation reaction (WOR) greatly restricts the efficiency of photocatalytic H2O2 production. Herein we prepare a bipyridine‐based covalent organic framework photocatalyst (denoted as COF‐TfpBpy) for H2O2 production from water and air. The solar‐to‐chemical conversion (SCC) efficiency at 298 K and 333 K is 0.57 % and 1.08 %, respectively, which are higher than the current reported highest value. The resulting H2O2 solution is capable of degrading pollutants. A mechanistic study revealed that the excellent photocatalytic activity of COF‐TfpBpy is due to the protonation of bipyridine monomer, which promotes the rate‐determining reaction (2 e− WOR) and then enhances Yeager‐type oxygen adsorption to accelerate 2 e− one‐step oxygen reduction. This work demonstrates, for the first time, the COF‐catalyzed photosynthesis of H2O2 from water and air; and paves the way for wastewater treatment using photocatalytic H2O2 solution.

Advanced treatment of landfill leachate using integrated coagulation/ photo-Fenton process through in-situ generated nascent Al3+ and H2O2 by Cl, N co-doped aluminum-graphite composite

Herein, we report an integrated coagulation/ photo-Fenton (CPF) process for advanced treatment of mature landfill leachate using nascent aluminum ions as coagulant and hydrogen peroxide (H2O2) as oxidant for Fenton reaction, which were in-situ produced by a novel chlorine and nitrogen co-doped aluminum-graphite (Cl, N-Al-Gr) composite. The coagulation of the MBR-treated landfill leachate was performed by nascent aluminum ions generated in Cl, N-Al-Gr/O2 system; and the resulting coagulation effluent was treated by photo-Fenton oxidation in the presence of ultraviolet (UVA). The Cl, N-Al-Gr composite exhibited excellent performance for in-situ H2O2 production (813.9 mg/L). The humic substances in landfill leachate could promote the cycle of Fe3+/Fe2+, and the removal efficiency of total organic carbon (TOC) and color was 88.1% and 97.6%, respectively under the optimized condition. The current study suggested that “coagulation + Fenton” process using nascent Al3+ as coagulant and in-situ generated H2O2 for Fenton oxidation could be a new way for wastewater treatment.

Green Synthesis of Reusable Adsorbents for the Removal of Heavy Metal Ions.

Industrial wastewater often contains heavy metals, like lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Overdoses of heavy metals will impose a severe threat to human health. Adsorption is the most efficient way of wastewater treatment for eliminating heavy metals. A novel material-reusable hydrogel-based adsorbent was developed in overcoming the regeneration issue. The polyethylene glycol diacrylate-3-sulfopropyl methacrylate potassium salt (PEGDA-SMP) hydrogel performed an ion-exchange rate to remove heavy metals from wastewater in 30–120 min. The adsorption capacity of PEGDA-SMP increases the increasing pH of a solution, in which pH 5 reaches the maximum. Pseudo-second-order adsorption and the Langmuir adsorption model can fully describe the adsorption properties of PEGDA-SMP for heavy metals. PEGDA-SMP prefers to exchange Pb2+ through K+, and its adsorption capacity can achieve 263.158 mg/g. Ag+, Zn2+, Ni2+, and Cu2+ were 227.27, 117.647, 102.041, and 99.010 mg/g, respectively. The hydrated ionic radius of the heavy metal might play an essential role to affect the adsorption preference. The removal efficiency of heavy metals can approach over 95% for each heavy metal. PEGDA-SMP performs rapid desorption and reaches desorption equilibrium in 15 min. After 10 consecutive adsorption–desorption cycles, the adsorption capacity remained over 90%. The hydrogel developed in this study showed reversible heavy metal absorption. Therefore, excellent adsorption–desorption properties of PEGDA-SMP can be potentially extended to industrial wastewater for removing heavy metals.

Enhanced Cr(VI) reduction on natural chalcopyrite mineral modulated by degradation intermediates of RhB

Wastewater with complex compositions of both heavy metals and organic pollutants is of critical environmental and socioeconomic threat worldwide, which urgently requires feasible remediation technologies to target this challenge. In this study, natural chalcopyrite (CuFeS2, NCP), the most abundant copper-based mineral in the Earth's crust, has been discovered to be a heterogeneous catalyst that can activate peroxydisulfate (PDS) for the simultaneous degradation of organic pollutant Rhodamine B (RhB) and reduction of hexavalent chromium (Cr(VI)). Batch experimental results indicate that both RhB and Cr(VI) could be simultaneously removed under a near-neutral condition in NCP/PDS combined system. The radicals SO4•− and •OH generated from PDS activation are the main oxidative species detected by electron paramagnetic resonance (EPR) spectroscopy. SO4•− acted as a predominant role in RhB degradation, while Cr(VI) reduction is mainly attributed to the oxidization of S2− and S22− species on NCP surface, as well as the photoreduction performance of NCP, which could be enhanced by the intermediates generated from RhB degradation. Density functional theory (DFT) calculation results disclose that Fe is the critical catalytic site for PDS activation. This work demonstrates a user-friendly strategy for remediation of complex wastewater containing both heavy metal and organic pollutants by combining photoreduction and advanced oxidation processes (AOPs) with natural minerals. It paves a way for wastewater treatment by utilizing low-cost natural abundant minerals as catalysts.

Three-dimensional hierarchical porous carbon derived from natural resources for highly efficient treatment of polluted water

BackgroundDealing with the ever-increasing water pollution has become an urgent global problem, especially the organic containing polluted water. Physical adsorption has become one of the most popular ways for removal of organic dyes from wastewater due to its low cost as well as high efficiency. However, the adsorption performance is still limited by the low specific surface area (SSA) and unsuitable pore size. Hence, it is still a challenge to synthesize active carbon (AC) with high SSA, suitable pore size distribution as well as low cost for polluted water treatment. Here, we report an efficient method to prepare AC with large SSA from jujube for removal of both cationic dye and anionic dye from aqueous solution. The present results demonstrate that biomass-derived hierarchical porous carbon has a real potential application for wastewater treatment.ResultsThe as-prepared hierarchical porous structure carbon material (PC-500-6) shows a high specific surface area (3203 m2/g) and pore size distribution in the range 0.8 to 3.0 nm, while exhibiting an enhanced adsorption performance for both methylene blue (MB) and methylene orange (MO) from an aqueous solution. The maximum adsorption capacity even reaches 925.93 mg/g and 1281.39 mg/g for MB and MO, which was calculated from Langmuir model. Through analysis of the adsorption data, it was found that the corresponding adsorption kinetic fits the pseudo-second-order model very well.ConclusionsIt can be concluded that the adsorption of MB has a strong correlation with SSA, pore size distribution as well as the pore volume. The present study paved a practical way for wastewater treatment by using biomass-derived hierarchical porous carbon.

Photothermal Membrane of CuS/Polyacrylamide–Carboxymethyl Cellulose for Solar Evaporation

Solar water evaporation is an environment-friendly and clean way of wastewater treatment and seawater desalination. However, a solar evaporator based on a hydrogel substrate still needs excellent t...

INFLUENCE OF PROBIOTIC PRODUCTS ON THE QUALITY OF WASTE WATER TREATMENT IN DAIRY INDUSTRIES

Nowadays there is the problem of the effective treatment of dairy industry plants’ wastewaters. Industrial wastewaters of these plants have high concentrations of organic matters and differ significantly from domestic wastewaters. The method of intensification of dairy wastewaters treatment in Tyumen region, using probiotic «PIP Plus WATER» (Belgium) is considered in this article. The article presents the results of conducted research on the impact of the probiotic on such wastewaters indices as pH, chemical oxygen demand, anionic surfactants, ammonium, nitrites, nitrates and phosphates concentrations. The comparison among different ways of wastewater treatment with probiotics has been made. Based on obtained results technological scheme of local treatment plant of dairy industry plant has been suggested.

Perspectives of bark dump recycling at wood processing enterprises

Woodworking and pulp-and-paper mill areas accumulate significant volumes of wood debarking waste, which is stored in bark dumps with a volume of up to 1 000 000 m3. Methods for recycling bark, both fresh and stagnant, are proposed through the production of fuel briquettes and pellets, composting, building materials, and the use of combustible gases that accumulate in the depths of the old bark layers. Characteristics of extractive substances obtained from bark are given and their fields of application are considered. Possible ways of recultivation of old bark dumps, ways of waste water treatment are offered. The recommendations on reduction of technogenic hazard of bark dumps are given and the necessity of constant monitoring of such objects is grounded. The technological scheme of complex use of bark dump materials on the basis of developments of Saint-Petersburg State Forest Technical University is proposed.