Organic Pollutants In Industrial Wastewater Research Articles

A study of highly efficient phenol biodegradation by a versatile Bacillus cereus ZWB3 on aerobic condition.

As one of the organic pollutants in industrial wastewater, phenol seriously threatens the environment and human health. Among various methods, microbial degradation of phenol possesses the advantages of nontoxicity and no secondary pollution. Therefore, search for microbial resources that can efficiently degrade phenol has become an important issue. In this study, a strain that could efficiently degrade phenol was isolated. The strain was identified as Bacillus cereus based on its morphology, physiological and biochemical features and 16S rRNA sequence analysis. The strain can completely degrade phenol up to 1,500 mg/L within 26 h (57.7 mg·L-1·h-1), under the optimum conditions, faster compared with the known degrading bacteria. The strain could efficiently remove phenol at a wide range of temperatures (22-37 °C) and pH (7-9), and Mn2+ and Zn2+ stress. Interestingly, this strain displayed the potential on microthermal environment, which could degrade 1,200 mg/L phenol within 36 h at 22 °C. Further, the strain had capacity that used a variety of aromatic compounds as the sole carbon source for growth. This study shows a useful biodegradation route on the wastewater treatment under high phenol concentration conditions, providing alternatives for environmental remediation.

Preparation of porous activated carbon with ultra-high specific surface area and its adsorption performance for specific organic pollutants in industrial wastewater

Porous activated carbon particles (GAC-1) with ultra-high specific surface area were prepared from starch by hydrothermal carbonization and high temperature activation. The porous structure and surface morphology of GAC-1 were characterized by N2 adsorption desorption isotherm and SEM. Compared with the commercially available activated carbon with the same particle size, the porous GAC-1 with ultra-high specific surface area shows better adsorption performance for CODCr, pyrazole and chloroform in wastewater. The results show that when the amount of activated carbon in the fixed bed is 160 g/L, the removal rate of CODCr, pyrazole and chloroform is 97.3%, 96.1% and 98.0%, respectively. The effluent meets the reuse requirements of the plant (CODCr ≤ 1500 mg/L). Finally, the activated carbon was regenerated five times by simple thermal regeneration method, and the COD removal rate could still reach 87.9%.

Chemical fingerprinting of organic micropollutants in different industrial treated wastewater effluents and their effluent-receiving river

Industry wastewater is considered one of the worst polluters of our precious water ecologies. However, the types of pollutants present in wastewater from industrial wastewater treatment plants (IWTPs) are still unclear. In this study, a simple and effective chemical fingerprinting method for checking the source-sink relationships among different industrial wastewaters and their effluent-receiving river was established. 107, 228, 155, and 337 chemicals were screened out in wastewater from electronics, steel, textile, and printing and dyeing plants, respectively. Chemical fingerprinting of the detected chemicals was performed, and results showed that aromatic compounds were the most prevalent among the pollutant categories (i.e., 56, 189, and 168 in electronics, iron and steel, and printing and dyeing plants, respectively). The traceability analysis of the chemicals selected in the effluent determined the characteristic pollutants of different industrial enterprises. Sixty-eight compounds were identified as the characteristic pollutants in the different process stages of wastewater of the four IWTPs. Of the 84 effluent-receiving river water signature pollutants, 47.6% (n = 40) were also detected in the effluent from the four IWTPs. Effective screening of organic pollutants in industrial wastewater and determining their sources will help accelerate the improvement of industrial wastewater treatment technology.

Characterization of submicro-sized Ag/ZnO particles generated using the spray pyrolysis method

Environmental issues caused by the rapid industrialization and urbanization of modern society are a serious problem. For example, conventional wastewater treatment technologies such as adsorption, coagulation, and filtration are expensive and cannot completely treat the discharge of organic pollutants in industrial wastewater. A promising alternative is the decomposition treatment of organic pollutants using an eco-friendly metal oxide photocatalyst. However, the rapid recombination of excited electron-holes limits the photolytic activity of semiconductor photocatalysts. This study investigates the inhibition of electron-hole recombination by supporting Ag nanoparticles on a ZnO photocatalyst. Ag/ZnO particles are generated under various conditions using ultrasonic spray pyrolysis. XRD analysis confirms the presence of Ag and ZnO crystal peaks in the generated particles. EDX mapping and STEM images show that Ag nanoparticles are well dispersed in ZnO. The photolysis rate of organic dye (rhodamine-B) is faster than that of ZnO in all Ag/ZnO particles, and particles with a 0.2 mass% silver nitrate supported on ZnO particles exhibit twice the photolysis activity of P25. Additionally, the optimal photolysis activity in 100 mL of 5 mg/L rhodamine-B aqueous solution with 10 mg of Ag/ZnO particles are confirmed and had excellent persistence and stability even during 7 reuses.

Magnetically separable NiFe2O4/sepiolite catalyst for enhanced ozonation treatment of quinoline and bio-treated coking wastewater in a catalytic ozonation system

In a quest to eliminate the bio-refractory organic pollutants in industrial wastewater, the NiFe2O4/SEP composites were synthesized via a sol-gel method and investigated by XRD, SEM, XPS, FTIR, VSM. The TOC removal increased from 16.82% to 69.35% in NiFe2O4/SEP+O3 system using quinoline as a target contaminant after 30 min, which is about 4.12 times as that in O3 system. The evolution of acetic acid, oxalic acid and formic acid in quinoline degradation was analyzed, saturated carboxylic acids were inertia to ozone molecules. However, 93.54% of oxalic acid was removed after 10 min, and 77.66% of acetic acid was degraded after 30 min in catalytic ozonation. The generation of small molecular organic acids could promote the Fe3+/Fe2+ redox cycle by complexing with Fe3+ on NiFe2O4/SEP, and then accelerated the formation of reactive oxygen species. In the presence of NiFe2O4/SEP, the high oxidation potential of •OH and •O2- contributed to an excellent TOC removal rate. Meanwhile, NiFe2O4/SEP was proved to be active for bio-treated coking wastewater in catalytic ozonation. The naturally fluorescent constituents in bio-treated coking wastewater were almost entirely removed by NiFe2O4/SEP+O3 system in 60 min. These findings indicated the good potential of NiFe2O4/SEP for practical applications in industrial wastewater treatment.

Preparation of a Phthalocyanine – Nanometal‐Coated Silica Microparticle Conjugate as Heterogeneous Photocatalyst and Investigation of Its Photocatalytic Activity

AbstractThis work details the preparation and characterization of a tetracarboxyzinc phthalocyanine (ZnTCPc) immobilized onto silica gel coated with gold nanometal (Au@SiO2) and investigates its photocatalytic activity for the first time. The immobilization of ZnTCPc on the Au@SiO2 surface was performed through pre‐anchorage of cysteine (CSH) via the post‐synthesis method, and then the ZnTCPc was conjugated to the nanometal surface (Au@SiO2) with an amide bond to obtain a heterogeneous photocatalyst (ZnTCPc−Au@SiO2). The prepared photocatalyst (ZnTCPc‐Au@SiO2) were characterized using various spectroscopic techniques such as Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV‐vis) spectrophotometry, and energy dispersive X‐ray (EDX) spectroscopy. Singlet oxygen quantum yields (ΦΔ) for both ZnTCPc and ZnTCPc‐Au@SiO2 were calculated, and the photocatalytic activity of the photocatalyst was tested for photodegradation of organic pollutants, namely Orange G (OG) and Methyl orange (MO), in aqueous solutions. The photodegradation process concluded in under 25 min. with a 20 mg dose of the ZnTCPc‐Au@SiO2 under visible light irradiation for 5 min. intervals in the presence of organic pollutants. The reusability of the photocatalyst was also tested. The results reveal that the photocatalyst (ZnTCPc‐Au@SiO2) has potential for use in the photodegradation of organic pollutants in industrial wastewater.

Spectrophotometric analysis of stability of gold nanoparticles during catalytic reduction of 4-nitrophenol.

Spectrophotometric monitoring of 4-nitrophenol (4-NP) reduction by sodium borohydride (NaBH4) using gold nanoparticles (GNPs) as a catalyst has been extensively studied, but the stability of GNPs in terms of change in the surface plasmon resonance (SPR) at different temperatures has not been explored. In the present investigation, our aim was to evaluate the SPR stability of GNPs as a catalyst during the reduction of 4-NP at different elevated temperatures (i.e. 30–60 °C) and sodium borohydride concentrations. Sensitivity of this degradation process toward concentration of GNPs at a range of temperatures is also evaluated. The spectrophotometric results reveal that up to 45 °C, 12 ± 1.5 nm catalyst has a consistent optical density (OD) during the entire 4-NP reduction process, which is related to the surface integrity of catalyst atoms. As the temperature approached 50 °C, the OD gradually decreased and showed a blue shift as the reaction proceeded, which could be related to a decrease in particle size or surface dissolution of gold atoms. The present study may find application in the design of catalysts for the reduction of organic pollutants in industrial wastewater at a range of temperatures.

Turning waste into wealth: facile and green synthesis of carbon nanodots from pollutants and applications to bioimaging.

In an effort to turn waste into wealth, Reactive Red 2 (RR2), a common and refractory organic pollutant in industrial wastewater, has been employed for the first time as a precursor to synthesize carbon nanodots (CNDs) by a facile, green and low-cost route, without utilization of any strong acids or other oxidizers. The detailed characterizations have confirmed that the synthesized CNDs exhibit good water dispersibility, with a mean particle size of 2.43 nm and thickness of 1–3 layers. Importantly, the excellent fluorescence properties and much reduced biotoxicity of the CNDs confer its potential applications in further biological imaging, which has been successfully verified in both in vitro (cell culture) and in vivo (zebrafish) model systems. Thus, it is demonstrated that the synthesized CNDs exhibit nice biocompatibility and fluorescence properties for bioimaging. This work not only provides a novel economical and environmentally friendly approach in recycling a chemical pollutant, but also greatly promotes the potential application of CNDs in biological imaging.

Full insights into the roles of pH on hydroxylation of aromatic acids/bases and toxicity evaluation

Advanced oxidation processes (AOPs) based on hydroxyl radicals (•OH) are the most important technologies for the removal of bio-recalcitrant organic pollutants in industrial wastewater. The pH is one of the crucial environmental parameters that affect the removal efficiency of pollutants in AOPs. In this work, the mechanistic and kinetic insights into the roles of pH on the hydroxylation of five aromatic acids and bases in UV/H2O2 process have been investigated using theoretical calculation methods. Results show that the reactivity of •OH towards the twelve ionic/neutral species is positively correlated with electron-donating effect of substituents, which contributes to the positively pH-dependent reactivity of aromatic acids and bases towards •OH. The hydroxylation apparent rate constants (kapp, M−1 s−1) (at 298 K) increase as the pH values increase from about 1 to 10, but they decrease as the pH values increase from about 10 to 14. However, the best pH values for degradation are not around 10 because the [•OH] decreases continuously with the increasing pH values from 3 to 9.5. Combining the factors of kapp and [•OH], the best degradation pH values are around 5.5~7.5 for p-hydroxybenzoic acid, p-aminophenol, aniline and benzoic acid, 3.0~7.5 for phenol and 5.5~7.5 for mixed pollutants of these aromatic acids/bases in UV/H2O2 process. Moreover, a significant number of hydroxylation by-products are more toxic or harmful to aquatic organisms and rat (oral) than their parental pollutants. Altogether, this work provides comprehensive understanding of the roles of pH on •OH-initiated degradation behavior of aromatic acids and bases.

Characterization and Evaluation of Copper Slag as a Bifunctional Photocatalyst for Alcohols Degradation and Hydrogen Production

With the goal of providing an economically viable method for reducing water pollution and health impact by the mezcal industry wastes, photocatalytic degradation of toxic alcohols using copper slag (CS) was evaluated, investigating the possibility for a concurrent hydrogen production. CS was characterized extensively by XRD, XRF, SEM–EDS, UV–Vis and electrochemical techniques to evaluate its properties as a photocatalyst. The slag consists of magnetite, fayalite and a silicate glass phase. CS showed a band gap of 2.75 eV, which is in the values range reported for fayalite, an n-type semiconductor with a clearly defined surface state. The band edge scheme for CS shows energy levels within the range required to perform the photocatalytic water reduction reaction, as well as the oxidation of the studied alcohols and their by-products. Experiments using UV and simulated solar light show that the efficiency of CS is higher in the visible range and that hydrogen production increases in the order methanol > propanol > isoamyl alcohol. An apparent quantum yield for methanol degradation of 40% under simulated solar light was obtained. This provides the prospect for a low cost and potential efficient photocatalyst for the oxidation of organic pollutants in industrial wastewater under solar radiation, with the simultaneous hydrogen generation.

Analysis for Effect of Chemical Pollutants on Wetland Ecology

Wetlands play an important role in maintaining ecological balance and promoting the development of surrounding economy. Chemical pollutants in industrial wastewater cause serious damage to the wetland ecosystem. For this, taking the polycyclic aromatic hydrocarbons (PAHs), one typical chemical organic pollutant in industrial wastewater as examples, this paper studies the effects of PAH on plants and microorganisms in wetlands. Then, the experimental simulation was conducted to study the degradation and absorption effects of wetland soil sediments and wetland plant (Spartina alterniflora) on PAHs, and also analyse the effects of PAHs on total biomass and microbial active enzymes in wetlands. The results show that the wetland ecosystem has significant absorption and degradation effects on chemical pollutants. The average removal rate of PHE is 26%, and the average removal rate of PYR is 20%; the content of PHE and PYR in leaves of Spartina alterniflora (S. alterniflora) is much smaller than that of root system, indicating that the root system of S. alterniflora is the main part of absorbing PAHs. PAHs pollution will cause serious damage to the distribution and content of microorganisms in the wetland. PHE causes the microbial content in the leaves of S. alterniflora to decrease by more than 35%, while PYR causes it to decrease by more than 26%. The plant-microbial combined treatment system in the wetland system can resist the harmful effects of chemical pollutants to a certain extent, and the bacteria in the plant roots are more sensitive to the response of chemical pollutants. This can provide a new research idea for the microbe-plant joint degradation of chemical pollutants in wetland ecosystems.

Recyclable Fenton-like catalyst based on zeolite Y supported ultrafine, highly-dispersed Fe2O3 nanoparticles for removal of organics under mild conditions

A versatile wet impregnation method was employed to conveniently and controllably deposit Fe2O3 nanoparticles on zeolites including commercial Y, mordenite and ZSM-5 with the similar framework Si/Al ratios and crystal sizes, respectively. The ultrafine Fe2O3 nanoparticles in size of 5nm can be highly dispersed on zeolite Y matrix due to its much better wettability than ZSM-5 and mordenite. By using the obtained Fe2O3/zeolite composite as the heterogeneous Fenton-like catalysts, the degradation of phenol as a model reaction was systematically investigated, including the zeolite supports, particle size and dispersion of Fe2O3, and reaction conditions of H2O2 concentration, temperature, and pH value. The catalyst based on zeolite Y with Fe loading of 9% exhibited the best phenol degradation efficiency (> 90%) in neutral pH within 2h. Its high catalytic activity in Fenton reaction can be attributed to the bifunctional properties of strong surface Brønsted acidity and high reactivity of octahedral Fe3+ in the highly-dispersed ultrafine Fe2O3 nanoparticles in size of 5nm, which were the primary active centers to quickly decompose H2O2 into hydroxyl radicals. Since phenol degradation can be performed under mild conditions of ambient temperature (283–323K) and a wide pH range (4.0–7.0), the catalysts can be easily recovered for recyclable use with stable degradation activity, which own the immense potential in deep treatment of organic pollutants in industrial wastewater.

Morphology-controlled synthesis of TiO2 nanostructures for environmental application

Uniform free standing TiO2 nanostructure with different shapes was extensively prepared by a template assisted hydrothermal method by controlling the pH and using Ti[OCH(CH3)2]4 as the titanium source. {101} and {200} planes of TiO2 were found to be the preferentially exposed active crystal planes for both nanospheres and nanostrips TiO2. The newly synthesised TiO2 materials were found to be very efficient for the photocatalytic degradation of organic pollutants in industrial wastewater.

VISIBLE LIGHT SOLAR PHOTOCATALYTIC DEGRADATION OF PULP AND PAPER WASTEWATER USING DYE-SENSITISED TIO2

With the growing number of industries there are large volumes of wastewater generated every day. Pulp and paper mills are highly polluting as they release effluents containing organic pollutants, and high levels of Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). Even though well-established processes exist to treat these effluents, there are only a few processes which are energy efficient. Conventional treatment methods are not effective for the degradation of toxic organic pollutants, hence other treatment techniques are necessary. One of the recent developments in this field is the Advanced Oxidation Process (AOP). Solar photocatalysis is a type of AOP which utilises UV light to activate semiconductor photocatalyst in order to produce highly reactive radical species. TiO2 is a widely used catalyst for this purpose, to oxidise or reduce the organic pollutants in industrial wastewater. However, photocatalysis using visible light has been receiving increased attention hence, modification of TiO2 is necessary for its enhanced response to visible light. There are many methods for modifying TiO2, such as doping and photo-sensitisation. This study focusses on the modification of TiO2 using the method of dye-sensitisation (photo-sensitisation) with the dyes rhodamine B and methylene blue. Solar photocatalytic experiments were carried out for the degradation of pulp and paper wastewater, at different conditions like varying catalyst loading (500mg, 600mg, 750mg and 1000mg of catalyst for 300ml of aqueous wastewater) and effluent concentration (20ml, 25ml, 30ml and 35ml of wastewater). Preliminary tests were done to determine the best conditions for photocatalytic degradation, and these were applied for final tests

Penelitian Pengolahan Air Limbah Industri Berkonsentrasi COD Tinggi Secara Anerobik dan Aerobik

One of the famous traditional food of Indonesia is tempe. Tempe is mainly produced in small scale industries. The wastewater from tempe industries contains a high organic pollutant especially from the boiling bean wastewater with COD chromium content 30, 000 mg/l -60, 000 mg/l and usually the effluent is directly blown down to the river without any treatment. To remove the high organic pollutant in industrial wastewater generally should be treated by the anaerobic and aerobic process to dare to the low cost, while the methane gas produced can be used as a fuel to boil or cook the tempe. The simple purification system of wastewater treatment with anaerobic UASB type followed with aerobic process has successfully, remove the total rate of COD content more than 90 % in anaerobic and 85 % in aerobic.

Removal of organic pollutants in industrial wastewater with an integrated system of copper electrocoagulation and electrogenerated H2O2

The effectiveness of organics removal of an integrated electrochemical process, namely, electrocoagulation with copper ions followed by the use of electrogenerated hydrogen peroxide was evaluated with an industrial wastewater. The copper (II) ions addition into the wastewater using electro-dissolution of copper electrodes, reduces the chemical oxygen demand (COD) by 56% after 30min of treatment, under optimal conditions of pH 2,8 and 14.2mAcm−2 of current density. The integrated electrochemical process reduces the COD by 78%, BOD5 by 81%, color by 97% and fecal coliforms by 99.9%. The wastewater quality was monitored using UV–Vis spectrometry and Z-potential in order to characterize raw and treated wastewater.

Laccase immobilized onto poly(GMA-MAA) microspheres for p-benzenediol removal from wastewater

Enzymes have already been extensively applied to degrade various organic pollutants in industrial wastewater, and how to improve the stability and reusability of the enzymes is critical to their practical application. In this study, poly(glycidyl methacrylate-methacrylic acid), poly(GMA-MAA), microspheres were prepared by suspension polymerization, and were used as a new support to immobilize Trametes versicolor laccase. The maximum loading capacity to immobilize enzyme reached as high as 44.78 mg protein/g support. The stability and reusability of laccase were greatly improved after immobilization on the microspheres. While the immobilized laccase was used as catalyst to remove p-benzenediol from wastewater, the removal efficiency reached 88.5%.

Efficient adsorptive removal of phenol by a diethylenetriamine-modified hypercrosslinked styrene–divinylbenzene (PS) resin from aqueous solution

Phenol is a typical organic pollutant in industrial wastewater and efficient adsorptive removal of phenol from aqueous solution has attracted many attentions in recent years. In the present study, a diethylenetriamine-modified hypercrosslinked styrene–divinylbenzene (PS) resin, HJ-M05, was synthesized, characterized and evaluated for adsorptive removal of phenol from aqueous solution, and two typical commercial polymeric adsorbents, Amberlite XAD-4 and XAD-7, were employed as references. The equilibrium capacity on HJ-M05 was much larger than those on XAD-4, XAD-7 and the precursor, HJ-55. The degree of the surface energetic heterogeneity of HJ-M05 was proven to be higher than XAD-4 and XAD-7 while the adsorbate–adsorbate interaction of the adsorbed phenol molecules on HJ-M05 was much less than that on XAD-4 and XAD-7. The kinetic data on HJ-M05 could be well plotted by the micropore diffusion model while those on XAD-4 and XAD-7 could not be fitted by this model. Thomas and Yoon models were more suitable for describing the dynamic data than the Clark model and the dynamic capacities on HJ-M05, HJ-55, XAD-4 and XAD-7 were calculated to be 201.7, 178.1, 107.5 and 74.80mg/g dry resin, respectively. 15.0BV (1BV=10ml) 1% of sodium hydroxide could regenerate the HJ-M05 resin column completely and the dynamic desorbed amount was almost equal to the dynamic adsorption amount.

Heterogeneous Catalytic Supercritical Water Oxidation of Refractory Organic Pollutants in Industrial Wastewaters

AbstractCatalytic supercritical water oxidation (CSCWO) is one of the most environmental-friendly advanced oxidation process. It makes a promising technology for the treatment of refractory organic pollutants in industrial wastewaters. Various heterogeneous catalysts including metal oxides have been extensively studied to enhance the efficiency of CSCWO. The present review is concerned about the literatures published in this regard. Phenolics, carboxylic acids and N-containing compounds were taken as model pollutants in most cases, and oxides of Cr, Mn, Co, V, Cu, Zn, Al, Ti and Ce were applied as heterogeneous catalysts. Reports on their characterization and catalytic performances for the CSCWO of aqueous pollutants are reviewed. Discussions are also made on the reaction mechanisms and kinetics proposed for heterogeneous CSCWO.

Dead‐End Liposomal Electro‐Filtration: Phenol Removal by Dioctadecyl Dimethyl Ammonium Chloride as a Case Study

AbstractAmong the important efforts that have been made for the removal of trace organic molecules, sorption by micelles and subsequent membrane filtration is a promising method which, however, still suffers from a number of disadvantages such as low efficiency and high energy consumption. In this article, we present the results of the sorption of phenol (as an important trace organic pollutant in industrial wastewater) to dioctadecyl dimethyl ammonium chloride (DODAC) liposomes, as well as the filtration properties of the resulting dispersion. Whereas the sorption of phenol by a 0.5 wt % DODAC dispersion at neutral pH and ambient temperature was only 26–35 %, it increased to above 95 % at pH 11. Applying an electric field during the filtration process considerably improved both the filtrate flow rate and the retention. An electric field of 5 V/cm increased the filtrate flow rate at 200 kPa 30‐fold.