Types Of Wastewater Research Articles

ELECTROPULSE EROSION OF ELECTRODES IN A LIQUID MEDIUM DURING THE TREATMENT OF GALVANIC WASTEWATER

The high-quality treatment of waste water from galvanic production sites is a recent problem in many fields of production. The electric pulse method is the most acceptable treatment method for this type of waste water. In the present paper are presents the survey results of the dependence of productivity of the main technological process (metal dispersion) on the energy and technological characteristics of a pulse generator and an electric discharge reactor. The survey results are necessary to determine the optimal operating modes and adequate design of equipment for waste water treatment of aircraft production galvanic areas. Physical and mathematical model which are presented and experimental data confirm the dependence of the magnitude and nature of the electric pulse erosion of the material on the dispersion conditions. Results of an experimental investigation of energy technology factors influence on the dispersion of metal in an electroerosive reactor are presented in the paper. A mathematical model of the dependence of the process productivity and specific energy expenditure has been obtained. The results of an experimental investigation of the discharge dimple on a microscope REM 106 for steel electrodes are presented.

Adsorption behavior and performance of ammonium onto sorghum straw biochar from water

Sorghum has been widely used for liquor production and brewing, but how to make efficiently utilize sorghum straw (SS) has become an urgent problem. Meanwhile, the wastewater produced by winemaking is typical organic wastewater with a high ammonium concentration. To solve the problem of resource utilization of SS and remove ammonium from water, SS was used to prepare biochar as an adsorbent for ammonium adsorption. Batch adsorption experiments were carried out to study the influencing factors and adsorption mechanisms of ammonium onto sorghum straw biochar (SSB). The results showed that the adsorption capacity of SSB was much higher than that of SS. The SSB pyrolyzed at 300 °C had the highest adsorption capacity. The favorable pH was 6–10, and the optimal dosage was 2.5 g/L. The adsorption process and behavior conformed to the pseudo-second-order kinetic and Langmuir isotherm adsorption models. The maximum ammonium adsorption capacity of SSB at 45 °C was 7.09 mg/g, which was equivalent to 7.60 times of SS. The ammonium adsorption of SS and SSB was mainly chemical adsorption. The regeneration test indicated that SSB had good regeneration performance after three adsorption-regeneration cycles. This work suggests that SSB could be potentially applied to sewage treatment containing ammonium to achieve the purpose of resource recycling.

Effect of aniline and antimony on anaerobic-anoxic-oxic system with novel amidoxime-modified polyacrylonitrile adsorbent for wastewater treatment

There has been increasing concern over the mixed discharge of municipal-textile composite wastewater, which remains challenging for typical wastewater treatment plant (WWTP) using anaerobic-anoxic–oxic process (AAO). Highly-toxic aniline and antimony, typical co-contaminants in textile wastewater, usually lead to increased chemical oxygen demand (COD) in influent and deteriorated effluent quality. Amidoxime-modified polyacrylonitrile (amPAN) adsorbent was prepared and added to adsorb antimony and facilitate substrate removal. With amPAN dosage at 6.0 g L−1 in oxic bioreactor, 64.2 ± 5.6% of antimony was removed from influent. Extracellular polymeric substance release was simultaneously changed with residual antimony concentration. Meanwhile, amPAN promoted the proliferation of Proteobacteria, Bacteroidetes and Epsilonbacteraeota serving as microorganism carrier. As a result, removal efficiencies of COD (94.4 ± 0.6%), ammonium (NH4+-N, 92.6 ± 3.3%), total nitrogen (TN, 76.4 ± 6.3%) and total phosphorus (TP, 93.4 ± 2.1%) were enhanced to meet Class 1A discharge standard in China. These results indicate that AAO with amPAN is promising for municipal-textile composite wastewater treatment.

Water cost for water purification: Renewability assessment of a typical wastewater treatment plant in China

In the context of severe water shortage and water pollution, wastewater treatment plays an important role in recycling water resources and improving water quality. Renewability of the wastewater treatment system as reflected by the water cost for water purification is revealed by a case investigation of a typical wastewater treatment plant in China, by means of the tiered hybrid method combining process analysis and systems input-output analysis. Based on a normalized indicator of water investment in water purified, the industrial freshwater use for per cubic meter of treated wastewater is calculated as 0.0069 m³, demonstrating a high renewability of the case wastewater treatment plant. Tap water and electricity inputs are the main contributors to the industrial water use of the wastewater treatment system that respectively account for 46.4% and 23% of the total, while construction stage contributes a non-negligible proportion of 19%. Compared with previous findings, however, the water cost for water purification by the case wastewater treatment plant is obviously larger, which may be attributed to the adoption of a most comprehensive input inventory and the tiered hybrid method that could effectively incorporate both onsite and offsite water use. The outcome presents a unique perspective for evaluating the renewability of wastewater treatment plants and provides a reference for water conservation.

Transformation products of tetracyclines in three typical municipal wastewater treatment plants

Antibiotics in the environment could undergo various processes with formation of transformation products, but little has been known about their occurrence and (eco)toxicological consequences. Here we investigated the occurrence and fate of nine transformation products of four tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in three municipal wastewater treatment plants (WWTPs) in Guangzhou, China. The results showed the detection of all the tetracyclines and their transformation products in the WWTPs, with mean concentrations ranging from 17.8 ng/L (anhydrotetracycline) to 49.1 ng/L (oxytetracycline) in influent, 3.03 ng/L (tetracycline) to 6.94 ng/L (4-epi-chlortetracycline) in effluent, and 19.8 ng/g (isochlortetracycline) to 503 ng/g (4-epi-tertracycline) in sludge, respectively. The transformation products of tetracycline, oxytetracycline, chlortetracycline and doxycycline accounted for 73%–83%, 26%–52%, 70%–73% and 69%–74% of total concentrations, respectively. The aqueous removal rates of tetracyclines and their transformation products in the three WWTPs ranged from 18.4% (demethyl-chlortetracycline) to 93.7% (oxytetracycline). Mass balance analysis based on both aqueous and solid phase showed that their removals were mainly attributed to the sludge adsorption. Residual tetracyclines and their transformation products in the effluents would pose no obvious ecological risks to three aquatic organisms (green algae, daphnia and fish). However, 43.5% of sludge samples had high risks from these tetracyclines and transformation products, especially the compounds with poor biodegradability. The results from this study suggest that transformation products should be included in future environmental monitoring and control.

Bioaerosols dispersed from a typical wastewater treatment plant with a membrane bioreactor: Emission characteristics, source analysis and health risk

Membrane bioreactors (MBRs) have become one of the most promising technologies in wastewater treatment. This study aimed to investigate the emission characteristics, source analysis and health risk of bioaerosols generated from a wastewater treatment plant (WWTP) with an MBR throughout the entire process. The results suggested that the MBR exhibited a high concentration of bacterial bioaerosols (2921–6173 CFU/m3) and fungal bioaerosols (77–673 CFU/m3) and a high proportion of the respiratory fraction (RF) of bioaerosols. In the MBR, Halomonas, Microvirga, and Geodermatophilus and Rubellimicrobium were the dominant bacteria, and the predominant fungi were Acidea, Neophaeosphaeria, and Cryptotrichosporon. Water soluble ions (WSIs) in the bioaerosols were mainly SO42-, NO3-, Cl-, Ca2+, Na+ and NH4+, with concentrations ranging from 18.68 to 183.41 μg/m3. Temperature, relative humidity (RH) and wind speed (WS) all had different influences on bacterial bioaerosols and fungal bioaerosols. Air was the major source of bioaerosols from the MBR. Bioaerosols in the fine grid (FG) and sludge dewatering room (SDR) were from wastewater, sludge and air. Furthermore, inhalation was the greatest pathway of bioaerosol exposure. The SDR, aeration tank (AerT) and MBR showed the highest risks of bioaerosols. Thus, bioaerosols from MBRs should be sufficiently investigated, and effective controls should be set up to protect workers and residents around plants.

Water quality improvement performance of two urban constructed water quality treatment wetland engineering landscaping in Hangzhou, China.

For typical wastewater treatment processes of urban sewage, plants are often noneffective to improve water qualities of lightly polluted domestic sewage, and urban constructed water quality treatment (WQT) wetlands designed with engineering landscape methods are utilized to optimize both water qualities and landscape values in recent years. The research determines the effects of two typical ecological engineering landscaping projects of urban constructed WQT wetlands by analysing their effects of wastewater quality improvements. Differences of water quality indicators (WQI) respectively among different treatment stages of wetlands includes surface flow wetland, vertical flow wetland, floating wetland islands etc., which have been measured and compared. Evaluation of urban constructed WQT wetlands engineering landscaping has been concluded based on comparisons among hydrological indicators and water quality indicators, i.e. pH, DO, NH3-N, CODCr, TP. Removal effects of individual indicators, includes NH3-N, CODCr and TP during different treatment stages have been quantitatively analysed. In accordance with quantitative analysis, benefits and deficiencies of practical landscape design of urban constructed WQT wetlands are concluded. By adapting proper principles in engineering landscaping, environmental and economic benefits can be achieved to create sustainable landscapes of urban constructed WQT wetlands.

Sewage-sludge derived activated carbon impregnated with polysulfide-sulfidated nZVI：A promising material for Cr(Ⅵ) reductive stabilization

This study aims to examine the reductive performance of a sulfidated iron-carbon composite synthesized using a sewage sludge from a typical biological wastewater treatment process. Sewage sludge was first carbonized under optimal conditions to prepare activated carbon (AC), followed by sequential treatment with nZVI and polysulfide to synthesize the iron-carbon composite S-nZVI/AC. Polysulfide was used to sulfurize nZVI due to its unique properties in stability, persistence and safety. Boehm titration and BET test showed that AC carried both acidic and basic sites in concentrations of 1.04 and 0.81 mmol/g per gram of material. The unmodified AC served mainly as a carrier to disperse nZVI grains from aggregation, although it also possessed a limited capacity of 3.5 mg/g for Cr(VI) sorption at neutral pH. Functionalized AC with nZVI boosted its capacity to about 29 times, while further treatment with polysulfide could further expand the material’s capacity by 36% to 136.0 mg/g. Sulfurizing the material with polysulfide also raised its reactivity as revealed by the kinetic experiments. Material characterizations suggested that multiple reductive species from S-nZVI/AC, including S(-Ⅱ) and Fe(Ⅱ) dissociated from FeS, Sx2-, and Fe0, might have participated in immobilizing Cr(VI). Specifically, S(-Ⅱ) and Sx2- were oxidized to SO42-, S2O32-, and S0, in decreasing order of concentration as inferred from XPS analysis.

Corrected response surface methodology for microalgae towards optimized ammonia nitrogen removal: A case of rare earth mining tailings wastewater in Southern Jiangxi, China

Using microalgae for rare earth elements wastewater treatment has been proved to be effective, however, the technology is challenged by the unstable performances caused by the changeable wastewater qualities and natural conditions. In this study, a corrected response surface methodology was first used to provide an optimized operation strategy for the application of wastewater treatment using microalgae, by investigating the effects and interrelations of three main factors including temperature, illumination intensity and microalgae concentration, taking rare earth elements wastewater in Southern Jiangxi as an example. Nine models were obtained using nine types of wastewater. The models were then modified by categorizing wastewaters into two classes (error range <12%) according to their initial ammonia nitrogen concentrations. The optimal conditions for ammonia nitrogen removal in class I and class II wastewater were as follows: temperature of 21.0 and 23.6 °C, illumination intensity of 46.8, 45.3 LX %, microalgae concentration of 1.64 and 1.67 g dry weight/L. The results are confirmed by stable operation of a continuous-flow photobioreactor for more than 122 days. The amount of microalgae required to treat wastewater under natural conditions is 1.5–1.8 g dry weight/L estimated by the corrected model. It implies that nearly 16,710 kg and 46,520 kg of ammonia nitrogen could be removed from two typical wastewaters with optimal microalgae dosage in 2020. The results demonstrated that corrected response surface methodology provides a powerful approach for optimizing the operational conditions for wastewater treatment by microalgae.

Synchronous complete COD reduction for persistent chemical-industrial organic wastewater using the integrated treatment system

• The concept of full COD reduction in wastewater was illustrated and into practice. • The selected real wastewater was highly acidic, high COD but low BOD. • COD in water and gas pathway were reduced synchronously during treatment process. • Tourmaline-based Fenton-like process avoid generation of iron sludge. • Microbial community succession for treating real RT-Base wastewater was revealed. Chemical-industrial organic wastewater often contains organic contaminants with low biodegradability. One challenge of chemical-industrial organic wastewater treatment is to select suitable pre-treatment combined with biological wastewater treatment. On the other hand, most wastewater treatment systems are open to the atmosphere, and the emission of gaseous organic matters usually occurs during the wastewater treatment processes. Thus, this work provided a conception of synchronous complete COD reduction during chemical wastewater treatment. Real p -Aminodiphenylamine (RT-Base) wastewater, a kind of typical chemical-industrial organic wastewater, was selected to verify the feasibility of the conception. An integrated closed system was utilized which involving a tourmaline-based Fenton-like process and Activated sludge (AS) process. The results showed that trimethylamine emitted after the wastewater pH adjustment and the emitted gaseous matter could be effectively removed by AS process. Additionally, the biodegradability of the wastewater was enhanced after the tourmaline-based Fenton-like pretreatment. Furthermore, the combination of Fenton oxidation with AS process provided a high total removal efficiency (COD removal rate = 98.87%). The emitted gaseous organic matter could be effectively captured and treated by another independent AS process, and there was no longer emitted gaseous organic matter in the off-gas. Microbial DNA analysis showed that the most dominant phyla in the activated sludge were bacteroidetes, proteobacteria, actinobacteria, and firmicutes. Carbohydrate metabolism was the most abundant pathway and its abundance increased 0.03%-1.19% after the treatment. Consequently, the conception of synchronous complete COD reduction in real chemical-industrial wastewater has been verified.

Metagenomics revealed the mobility and hosts of antibiotic resistance genes in typical pesticide wastewater treatment plants

Pesticide showed a crucial selective pressure of antibiotic resistance genes (ARGs) in the environmental dimension, especially in the pesticide wastewater treatment process, where the information on the mobility and hosts of ARGs was very important but limited. This study tried to clarify the mobile antibiotic resistome and ARG hosts in three typical pesticide wastewater treatment plants (PWWTPs) through metagenomics. Results showed that ARGs associated with antibiotic efflux and multi-drug resistance generally dominated in the PWWTPs, and the relative abundance of ARGs was generally higher in the water phase than that in sludge phase. The mobile antibiotic resistome accounted for 43.6% ± 16.2% and 44.8% ± 18.0% of the total relative abundance of ARGs in the water phase and sludge phase, respectively. The tnpA, IS91 and intI1 were the dominant mobile genetic elements (MGEs) closely associated with ARGs. MCR-5 and MCR-9 were first identified in the PWWTPs and located together with the tnpA, tnpA2 and int2. The potential human pathogens belonging to Citrobacter, Pseudomonas, Enterobacter, Acinetobacter, and Kluyvern were the major ARG hosts in the PWWTPs. Statistical analysis indicated that microbial community contributed the most to the occurrence of antibiotic resistome, and the reduction of the major ARG hosts was crucial from the perspective of ARGs control.

Statics simulation of the sulphate iron-containing wastewater neutralization process

At the present stage of technical progress, all industries face an extremely complex problem of creating reliable barriers that prevent the penetration of industrial emissions into the environment. Currently, the issues of stabilizing the quality of wastewater treatment have become especially important in connection with the task of developing wastewater-free industrial complexes. Among the complex scientific and technical problems associated with this task, the problem of stable and reliable maintenance of water quality parameters at the outlet of technological systems is crucial, as leakage of pollutants immediately affects the state of basic production, disrupting its technology and infecting ecosystems.&#x0D; The focus of industry on a sharp reduction in emissions and on the creation of industrial cycles with circulating water supply requires intensive efforts to improve the wastewater treatment technology, the introduction of high-performance processes and devices, as well as the synthesis of control systems for typical wastewater treatment processes. &#x0D; For the performance of automated control systems for typical cleaning processes, it is necessary to develop a software package on the basis of appropriate mathematical models of typical processes. To obtain them, methods of mathematical and simulation modeling and variance analysis were used.&#x0D; In order to assess the quality of modeling, the presented mathematical model describing the statics of the neutralization process for ferrous sulfate water was tested for compliance. To do this, two experiments were performed (the first at an initial concentration of sulfuric acid of 800 [mg/l] and ferrous sulfate of 4000 [mg/l] and the second at an initial concentration of sulfuric acid of 800 [mg/l] and ferrous sulfate of 2000 [mg/l]). First of all, a precondition for the reproducibility of experimental results was verified using the Cochrane test. The mathematical model was verified for adequacy on the basis of Fisher's criterion for the significance level q = 0.05 with degrees of freedom j1 = 16 and j2 = 17.&#x0D; For the first experiment, Grozr = 0.50557 and Gmab = 0.73; i.e., Grozr &lt; Gmab and dispersions are homogeneous. Frozr = 1.0225 and Fmab = 2.4 and thus Frozr &lt; Fmab, and there is no reason to say that the model is inadequate.&#x0D; For the second experiment, Grozr = 0.50308 and Gmab = 0.73; i.e., Grozr &lt; Gmab and dispersions are also homogeneous. Frozr = 1.0005 and Fmab = 2.4 and thus Frozr &lt; Fmab, which also indicates that the model is adequate.&#x0D; The issue related to the performance of technological systems for wastewater treatment in non-stationary modes is directly dictated by the specific operating conditions of treatment facilities, which are expressed by the instability of parameters at their inlet. The inability to apply the necessary technological action to the flow in time is a serious obstacle to the implementation of the cleaning depth, which is guaranteed by the physicochemical basis of the methods incorporated in technological systems and requiring cleaning standards. The operator cannot handle this complex task manually. On the basis of the proposed mathematical model, a structural-parametric diagram of the automated process control system has been developed, which makes it possible to proceed to the elaboration of algorithms and software for the control system necessary for automated control of the wastewater treatment process.

Treatment of coking wastewater in a heterogeneous electro-Fenton system: Optimization of treatment parameters, characterization, and removal mechanism

Coking wastewater is a typical refractory industrial wastewater with complex hazardous materials and high organic content. A novel heterogeneous electro-Fenton system with a homemade iron-loaded activated carbon cathode was used to treat coking wastewater. Based on response surface methodology, chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) were used as research indicators for the optimization of the reaction parameters. Under the optimal conditions of 1 cm electrode spacing, 10 V applied voltage, and initial pH of 3.88, the COD removal rate in several experiments was 88.91–96.65%, and the NH3-N removal rate in several experimental runs was up to 100%. We used ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, three-dimensional excitation-emission matrix fluorescence, gas chromatography–mass spectrometry, and color analysis for analyses; and found that the cyclic aromatic compounds and hazardous materials containing unsaturated double and triple bonds could be effectively degraded by the modified electro-Fenton method. Additionally, the color of the coking wastewater can also be effectively removed using this technique. The studied mechanisms and UV254 analysis illustrated that the modified electro-Fenton method can effectively degrade COD and NH3-N, remove most hazardous materials, and improve the biodegradability of coking wastewater.

Degradation of organic compounds in hypersaline wastewater concentrate by a supercritical oxidation approach

ABSTRACT Hypersaline wastewater is a typical industrial wastewater produced by iron and steel metallurgy, food material processing and other industries. Aiming at a waste liquid produced by mechanical vapour recompression evaporation and concentration in Tianjin coastal industrial zone, an environment-friendly supercritical water oxidation technology was used to efficiently remove the high-content organic matter in the hypersaline wastewater concentrate (HWC). A comparison of the degradation effects of various oxidants in the supercritical state showed that hydrogen peroxide (H2O2) could be used as a suitable agent for processing the HWC. The reaction parameters were systematically optimised by single-factor experiment and response surface design. The degradation mechanism and reaction characteristics were analyzed using gas chromatography mass spectrometry. Solid residues were characterised by field emission scanning electron microscope. The results indicated that when the dosage of hydrogen peroxide was 6.39%, the reaction temperature was 380°C, the reaction time was about 90 min and the optimal total organic carbon removal rate was 96.22%. Furthermore, it was found that hydroxyl radicals produced by hydrogen peroxide initiated the bond breaking and ring-opening reactions in organic matter, which eventually degraded organic matter into water and carbon dioxide.

Fate of household and personal care chemicals in typical urban wastewater treatment plants indicate different seasonal patterns and removal mechanisms

Studies on the presence and fate of household and personal care chemicals (HPCCs) in wastewater treatment plants (WWTPs) are important due to their increasing consumption worldwide. The seasonal patterns and removal mechanisms of HPCCs are not well understood for WWTPs that apply different treatment technologies. To answer these questions, the sewage and sludge samples were taken from 10 typical WWTPs in Northeast China. Levels of UV filters in the influents in the warm season were significantly greater than that of the cold season (p < 0.05). Significant seasonal differences were found for the removals of many HPCCs. Results revealed that the highest removal efficiencies were found for linear alkylbenzene sulphonates with values ranging from 97.2% to 99.7%, and the values were 50.0%–99.9% for other HPCCs. The SimpleTreat model demonstrated that the studied WWTPs were operating with high efficiency at the time of sampling. The sorption of HPCCs to sludge can be strongly associated with their physicochemical parameters. Mass balance calculation suggested that sorption was the dominant mechanism for the removal of antimicrobials, while degradation and/or biotransformation were the other mechanisms for removing the most HPCCs in the WWTPs. This study real the factors influencing the seasonal patterns and removal mechanisms which imply the need for further studies to fully understands the plant and human health implications as sludge could be used in the municipal land application of biosolids.

Polishing micropollutants in municipal wastewater, using biogenic manganese oxides in a moving bed biofilm reactor (BioMn-MBBR)

Conventional wastewater treatment plants (WWTPs) cannot remove organic micropollutants efficiently, and thus various polishing processes are increasingly being studied. One such potential process is utilising biogenic manganese oxides (BioMnOx). The present study operated two moving bed biofilm reactors (MBBRs) with synthetic sewage as feed, one reactor feed was spiked with Mn(II) which allowed the continuous formation of BioMnOx by Mn-oxidising bacteria in the suspended biofilms (i.e. BioMn-MBBR). Spiking experiments with 14 micropollutants were conducted to investigate if BioMnOx combined with MBBR could be utilised to polish micropollutants in wastewater treatment. Results show enhanced removal by BioMn-MBBR over control MBBR (without BioMnOx) for specific micropollutants, such as diclofenac (36% vs. 5%) and sulfamethoxazole (80% vs. 24%). However, diclofenac removal was significantly inhibited when municipal wastewater was fed, and a further batch experiment demonstrates the reduced removal of diclofenac could be due to (unusual) higher pH in municipal wastewater compared to synthetic sewage. A shift in bacterial community was also observe in BioMn-MBBR over long-term operation. Overall, BioMn-MBBR in this study shows great potential for practical application in removing a larger range of micropollutants, which could be applied as an efficient polishing step for typical municipal wastewater.

Changes in antibiotic resistance genotypes and phenotypes after two typical sewage disposal processes

Antibiotic resistome is a growing concern around the world. Wastewater treatment plants (WWTPs) have been identified as hotspots for antibiotic resistance gene (ARG) research. However, the distribution of antibiotic resistance genotypes and phenotypes in biofilm wastewater treatment system is poorly understood. In this study, the abundance and fate of antibiotic resistance genotypes and phenotypes in two typical wastewater treatment processes [biological aerated filter (BAF), anaerobic-oxic (A/O)] were quantitatively studied. The average removal rate of total ARGs was greater than 90%. In the biological treatment unit, the abundance of ARGs increased in the A/O unit and decreased in the biofilm unit. In addition, the resistance of tetracycline resistant bacteria changed after sewage disposal, which was closely related to the evolution of bacterial community. In total, the removal rate of resistance bacteria in A/O system was lower than that in BAF system. Genotypes were the basis of determining the phenotypes of microbial resistance. But it is necessary to pay close attention to antibiotic resistance phenotype due to its high variability. More specifically, antibiotic resistance mitigation in WWTPs should focus more on removing bacterial hosts to reduce the release of ARGs into the environment.

Efficient Degradation of Iopromide by Using Sulfite Activated with Mackinawite.

Iopromide (IOP), an iodinated X-ray contrast medium (ICM), is identified as a precursor to iodide disinfection byproducts that have high genotoxicity and cytotoxicity to mammals. ICM remains persistent through typical wastewater treatment processes and even through some hydroxyl radical-based advanced oxidation processes. The development of new technologies to remove ICMs is needed. In this work, mackinawite (FeS)-activated sulfite autoxidation was employed for the degradation of IOP-containing water. The experiment was performed in a 500 mL self-made temperature-controlled reactor with online monitoring pH and dissolved oxygen in the laboratory. The effects of various parameters, such as initial pH values, sulfite dosages, FeS dosages, dissolved oxygen, and inorganic anions on the performance of the treatment process have been investigated. Eighty percent of IOP could be degraded in 15 min with 1 g L−1 FeS, 400 μmol L−1 sulfite at pH 8, and high efficiency on the removal of total organic carbon (TOC) was achieved, which is 71.8% via a reaction for 1 h. The generated hydroxyl and oxysulfur radicals, which contributed to the oxidation process, were identified through radical quenching experiments. The dissolved oxygen was essential for the degradation of IOP. The presence of Cl− could facilitate IOP degradation, while NO3− and CO32− could inhibit the degradation process. The reaction pathway involving H-abstraction and oxidative decarboxylation was proposed, based on product identification. The current system shows good applicability for the degradation of IOP and may help in developing a new approach for the treatment of ICM-containing water.

A hand-held optoelectronic tongue for the identification of heavy-metal ions

Heavy-metal ions detection conventionally relies on standard instruments that are complicated, time-consuming and constrained to laboratories. To mitigate this problem, we developed a hand-held and cost-effective smartphone-integrated analysis platform that allows fast identification of heavy-metal ions pollution caused by industrial wastewater discharge. This portable platform integrates a colorimetric sensor array consisting of plasmonic nanocolorants and organic chromophores to detect typical heavy-metal ions at the ppm level within 15 s. The image of the colorimetric sensor array is transmitted to the Complementary metal–oxide–semiconductor (CMOS) imager of the smartphone via 96 individual optical fibers, generating RGB differential fingerprints and quantitatively analyzed by pattern recognition algorithms. Facile identification of 13 common heavy-metal ions (Hg2+, Cd2+, Cr6+, Pb2+, Ni2+, Se4+, Mg2+, Ba2+, Zn2+, As3+, Mn6+, Fe3+, Cu2+) was demonstrated using several different multivariate analyses of the digital data library, including principal component and hierarchical cluster analysis. Furthermore, we demonstrated the multiplexed detection and classification of 4 typical industrial wastewater models (Electroplating, Battery, Metallurgical, Pesticide wastewater) and real water samples with this portable platform, and achieved good discrimination and reproducibility. Combined with edge computing of smartphones and Internet-of-Things (IoT) cloud infrastructure, the portable platform shows feasible potential for pollution traceability, environmental monitoring, and water quality analysis.

Enhanced performance of anaerobic two-phase reactor treating coal gasification wastewater with the assistance of zero valent iron under co-digestion conditions

Coal gasification wastewater (CGW) is a typical industrial wastewater that is difficult to degrade as it contains a large number of refractory and toxic pollutants, such as high concentrations of phenols.The aim of this study is to investigate an anaerobic two-phase reactor treating synthetic CGW under co-digestion conditions. The optimum dosages of co-substrate (glucose = 1000 mg/L), zero valent iron (ZVI) (2 g/L), and hydrolysis acidification time (12 h) were explored by batch tests. The results indicated that the concentration of total phenols declined from 636 mg/L to 376 mg/L when the cumulative methane production increased to 145 mL. In the long-term operation of the anaerobic two-phase reactor, 1,000 mg/L glucose was added to the influent, and 2 g/L ZVI was added in the methanogenic phase, respectively. HRTs in acidogenic and methanogenic phases were kept at 12 h and 48 h, respectively. The average acetate and TVFAs concentrations remained at approximately 852 mg/L and 1042 mg/L, respectively. The result showed that the concentrations of influent and effluent COD were approximately 3,191 mg/L and 412 mg/L, respectively, while those of influent and effluent total phenols were approximately 655 mg/L and 23 mg/L, respectively. The removal efficiencies of total COD and total phenols were over 86% and 96%, respectively. In addition, the total methane production rose to 250 mL/d. Microbial community structure analysis demonstrated that the acidogenic phase contained most types of microbial species and the most complex community diversity in the anaerobic system and that direct interspecies electron transfer (DIET) might occur between the potential electroactive bacteria Chloroflexi and the archaea Methanobacteriales and Methanosaeta, respectively.