Industrial Wastewater Treatment Plant Research Articles

Spatiotemporal distribution and fates of neonicotinoid insecticides during the urban water cycle in the lower reaches of the Yangtze River, China

Neonicotinoid insecticides (NNIs) are the most popular insecticides worldwide, yet their spatiotemporal distribution and fates during the urban water cycle remain limited on a large watershed scale. Thus, we investigated ten kinds of NNIs in surface water from the lower reaches of the Yangtze River and hubs of the urban water cycle in all seasons. In brief, eight out of ten NNIs were detected, and thiamethoxam (THM), imidacloprid (IMI), and dinotefuran (DNT) were the most abundant NNIs in surface water, with concentrations of 0.29–48.15 ng/L, 1.69–20.57 ng/L, and 0.98–25.32 ng/L, respectively. The average concentrations of total NNIs in summer were 1.96–4.41 folds higher than those in other seasons. NNIs in the effluents of municipal wastewater treatment plants (WWTPs) were lower than those in surface water, while the average concentrations of total NNIs in the effluents of industrial WWTPs were 1.56–6.86 folds higher than those in surface water, indicating that insecticide production is an important source for NNIs in surface water. DNT was the most recalcitrant NNI in WWTPs, with an average removal efficiency of 49.89%, while in drinking water treatment plants (DWTPs), the removal efficiencies of most NNIs were limited, except for clothianidin (CLO) (90%). Risk assessment showed that NNIs posed medium or high risks to aquatic life, and DNT contributed 26.86–51.48% to the cumulative risks of detected NNIs. This study investigates the spatiotemporal distribution and risks of NNIs and provides information for the supervision of NNIs in the Yangtze River basin, China.

Deterministic mechanisms drive bacterial communities assembly in industrial wastewater treatment system.

Microbial communities are responsible for biological treatment of many industrial wastewater, but our knowledge of their diversity, assembly patterns, and function is still poor. Here, we analyzed the bacterial communities of wastewater and activated sludge samples taken from 11 full-scale industrial wastewater treatment plants (IWWTPs) characterized by the same process design but different wastewater types and WWTP compartments. We found significantly different diversity and compositions of bacterial assemblages among distinct wastewater types and IWWTPs compartments. IWWTPs bacterial communities exhibited a clear species abundance distribution. The dispersal-driven process was weak in shaping IWWTP communities. Meanwhile, environmental and operating conditions were important factors in regulating the structure of the activated sludge community and pollutants removal, indicating that bacterial community was largely driven by deterministic mechanisms. The core microbial community in IWWTPs was different from that in municipal wastewater treatment plants (MWWTPs), and many taxa (e.g. the genus Citreitalea) rarely were detected before, indicating IWWTPs harbored unique core bacterial communities. Furthermore, we found that bacterial community compositions were strongly linked to activated sludge function. These findings are important to both microbial ecologists and environmental engineers, who may optimize the operation strategies jointly for maintaining biodiversity, which in turn may promote a more stable performance of the IWWTP. Overall, our study enhances the mechanistic understanding of the IWWTP microbial community diversity, assembly patterns, and function, and provides important implications for microbial ecology and wastewater treatment processes.

Relations Among Sludge Rheological Properties And Operational Problems In An Industrial Zone Wastewater Treatment Plant

The main objective is to examine how the viscosity values change in order to solve the problems frequently encountered in transmission lines in this study. Sludge samples from chemical and biological treatment process were taken in two different stages of nearby industrial zone wastewater treatment plant (IZWWTP). Physical, chemical and rheological properties of sludge samples were investigated in two different seasonal periods (October and February). The pH, temperature, conductivity, total suspended solid, chemical oxygen demand and total volatile solids of the sludge samples were determined in the first phase of the study. In the second phase, the shear stress and viscosity of the samples were determined to different shear rates using Brookfield DV-II+Pro viscometer. The rheological behaviors were modelled using Bingham, Ostwald and Herschel-Bulkley. In operating periods when viscosity increases, alternative coagulants may be preferred, chemical type or amount may be changed in the chemical process. Sludge pumps within the facility should be selected according to the rheological properties of the treatment sludge. Seasonal operating measures to be taken according to rheological properties can reduce operating costs.

Industrial Pilot for Assessment of Polymeric and Ceramic Membrane Efficiency in Treatment of Liquid Digestate from Biogas Power Plant

Due to the depletion of available water resources and the consistently rising environmental pollution levels, the exploitation of the digestate generated as an unfavorable by-product of the industrial wastewater treatment plants, could not only offer a readily available source of recycled water, but also an efficient agricultural fertilizer. However, the first step for the utilization of the digestate is the removal of any potentially harmful contaminants, and ultrafiltration membranes can provide successful remediation routes in this direction. This work investigates the industrial pilot-scale purification and reusability of the liquid digestate derived from the anaerobic treatment of waste mixtures of high organic content, using ultrafiltration membrane technology. Two different types of ultrafiltration membranes, polymeric and ceramic, were evaluated regarding their efficiency and long-term performance, parameters that heavily affect the overall costs of the operational unit. Our results indicate that the ceramic membranes exhibited a superior performance compared to its polymeric analogues, such as a higher flux, as well as significantly increased lifetime, signifying promising cost-effective and long-term applicability on an industrial level. In addition, the analytical physicochemical characterization of the ultrafiltration reject indicated its high nutrient value, suggesting its highly promising exploitation as an added value fertilizer, further enhancing the sustainability of the proposed approach.

Sludge recovery from industrial wastewater treatment

Industry is a fundamental sector that allows mass production to support a large population. As population grows, many industries produce large amounts of industrial effluents with different pollutants, that must be removed at the industrial wastewater treatment plants, with the consequent production of large amounts of sludge. The present study was conducted to identify and evaluate different sludge treatment/valorisation methodologies, being given priority to the valorisation in detriment of the elimination operations, like incineration or landfill. Therefore, sludges from the wastewater treatment plant of a resin industry, after dehydration operation by a press, were submitted to several valorisation methodologies, such as: application in anaerobic digestion aiming the production of biogas and allowing energy recovery, use in the preparation of adsorbents for the treatment of industrial wastewater, use as cement replacement in mortar production, and application of heterogeneous catalysts to produce biodiesel. The results revealed that all methodologies can be applied as sludge recovery. However, it is possible to conclude that the most promising industrial sludge treatment/recovery hypothesis is anaerobic co-digestion followed by the production of heterogeneous catalysts for biodiesel production.

Emission of Bisphenol A and Four New Analogs from Industrial Wastewater Treatment Plants in the Production Processes of Polypropylene and Polyethylene Terephthalate in South America

The study of the presence of bisphenol analogs in the environment has been very relevant in recent years because their toxic potential has been discovered, and since they are not regulated like bisphenol A, their use and presence in industry has been excessive. This study identifies and quantifies for the first time the presence of bisphenol A and four uncommon bisphenol analogs in waste from polypropylene (PP) and polyethylene terephthalate (PET) production processes that may originate from the degradation of some compounds used during resin synthesis in Colombia to determine the effectiveness of removal of these components. The data obtained show that the treatments used in these waters are insufficient to eliminate 40% of the bisphenols present in them, and when evaluating the profiles of compounds, it is clear that the compound with the highest removal during the PP process was D-BPA-1, while the compound with the highest removal during the PET process was D-BPA-4, indicating that identification and elimination systems for bisphenols are rudimentary.

The advantages of co-digestion of vegetable oil industry by-products and sewage sludge: Biogas production potential, kinetic analysis and digestate valorisation.

The production of edible vegetable oils generates considerable amounts of energy-rich waste, which is usually not utilised fully. Besides, inefficient management of such wastes can have a negative impact on the environment. On the other hand, this waste can also serve as a raw material for the production of high value-added products, such is biogas. The mono-digestion of seven different by-products and wastes from the vegetable oil industry was investigated in this study: Pumpkin seeds press cake (PSPC), grape seeds press cake (GSPC), olive mill pomace (OMP), coconut oil cake (CC), filtration additive (FA), spent bleaching earth (SBE) and sludge from a vegetable oil industry (SOI) wastewater treatment plant. In addition, co-digestion of these substrates was performed with municipal sewage sludge (SS). Besides inoculum, rumen fluid was added to the reactors to enhance biogas production. The biogas production potential of the tested substrates was monitored by measuring various parameters. A kinetic analysis was later carried out and a growth test was performed on the digestates to evaluate their potential for agricultural use. The highest biogas yields in the mono-digestion test were obtained with the substrates with the highest fat content: 1402, 1288, 830 and 750mL of biogas/gVS for SOI, FA, PSPC and CC substrate, respectively. Co-digestion of SS with by-products of vegetable oil industry such as FA, SBE, CC, SOI and PSPC increased the biogas yields by 94.9%, 74.1%, 30.8%, 27.4% and 23.6% compared to SS mono-digestion. Furthermore, the data for mono-digestion of PSPC, GSPC, and FA, and co-digestion of SS with these substrates, CC and SBE, have not been found in the literature to date. The maximum methane content ranged from 61 to 74vol%, while the chemical oxygen demand removal efficiency ranged from 42 to 78%. Relatively high fatty acids contents and ammonium concentrations were measured in the reactors. Kinetic analysis showed the best fit to the experimental data for the Cone kinetic model (R2>0.98). The First order kinetic model, Monod, and the modified Gompertz model also exhibited high R2 values. The digestates obtained from co-digestion proved to be excellent in the cress seeds growth test at digestate concentrations of 5-10wt%, while higher concentrations had a toxic effect.

Review: Wastewater Treatment in Different Industries

Abstract: Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environment or is reused for various purposes (called water reclamation). The treatment process takes place in a wastewater treatment plant. There are several kinds of wastewater which are treated at the appropriate type of wastewater treatment plant. For domestic wastewater (also called municipal wastewater or sewage), the treatment plant is called a sewage treatment plant. For industrial wastewater, treatment either takes place in a separate industrial wastewater treatment plant, or in a sewage treatment plant (usually after some form of pre-treatment). Further types of wastewater treatment plants include agricultural wastewater treatment plants and leachate treatment plants. Processes commonly used in wastewater treatment include phase separation (such as sedimentation), biological and chemical processes (such as oxidation) or polishing. The main by-product from wastewater treatment plants is a type of sludge which is usually treated in the same or another wastewater treatment plant. Biogas can be another by-product if anaerobic treatment processes are used. Treated wastewater can be reused as reclaimed water. The main purpose of wastewater treatment is for the treated wastewater to be able to be disposed or reused safely. However, before it is treated, the options for disposal or reuse must be considered so the correct treatment process is used on the wastewater. Performance ofstate owned sewage treatment plants, for treating municipal waste water, and common effluent treatment plants, for treating effluent from small scale industries, is also not complying with prescribed standards. Thus, effluent from the treatment plants, often, not suitable for household purpose and reuse of the waste water is mostly restricted to agricultural and industrial purposes. The development of innovative technologies for treatment of wastewaters from various industries isa matter of alarming concern for us. Although many research papers have been reported on wastewater pollution control studies, but a very few research work is carried out for treatment of wastewater of steel industries, especially in reference to development ofdesign of industrial effluent Treatment Plants (ETP)system. Another beneficial aspect of this research work will be recycling, reuse of water and sludge from steel industry The whole technologies for treating industrial wastewater can be divided into four categories: - Chemical, Physical, Biological and mathematical approaches.

Process monitoring of nonlinear uncertain systems based on Part Interval Stacked Autoencoder and Support Vector Data Description

Chemical process measurement may cause inaccuracy and uncertainty in some parts of the measurement data due to equipment aging and environmental conditions, such as temperature, humidity, gas pressure, gas flow, and other related factors. Uncertain data of this kind commonly fluctuate in an interval centered on the true value. Given the uncertain characteristics of some parts of the measurement data, the certain of some parts, and the nonlinearity of the industrial process, the present paper proposes a novel algorithm of process monitoring and fault diagnosis called Part Interval Stacked Autoencoder and Support Vector Data Description (PISAE–SVDD). The loss function of Stacked Autoencoder (SAE) is improved in this algorithm. In certain measurement data, the reconstruction error value is the mean square error of the original input data and output data. By contrast, uncertain measurement data provide a certain allowable range for reconstruction error value. The error value of measurement data is considered as zero within this range. The reconstruction error value of measurement data beyond the allowable range is calculated in the same way as for certain measurement data. At the same time, the characteristic information of the industrial process is extracted through the strong nonlinear characterization ability of SAE. Support Vector Data Description is then used to obtain the control limit of the fluctuation range of the normal working condition based on the SAE feature information data extracted from normal samples. This approach is adopted to realize the process monitoring of the industrial process with partial uncertain measurement. To detect fault, this algorithm was applied to the numerical simulation, the Tennessee Eastman process, and the process in industrial wastewater treatment plants, and then compared with other advanced algorithms. The results indicate the excellence and high efficiency of the PISAE–SVDD algorithm in the field of process monitoring.

Economic, technical, and environmental evaluation of retrofitting scenarios in a full-scale industrial wastewater treatment system

The use of mathematical models is a well-established procedure in the field of (waste) water engineering to “virtually” evaluate the feasibility of novel process modifications. In this way, only options with the highest chance of success are further developed to be implemented at full-scale, while less interesting proposals can be disregarded at an early stage. Nevertheless, there is still lack of studies, where different plant-wide model predictions (effluent quality, process economics, and technical aspects) are comprehensibly verified in the field with full-scale data. In this work, a set of analysis/evaluation tools are used to assess alternative retrofitting options in the largest industrial wastewater treatment plant in Northern Europe. A mechanistic mathematical model is simulated to reproduce process behavior (deviation < 11%). Multiple criteria are defined and verified with plant data (deviation < 5%). The feasibility of three types of scenarios is tested: (1) stream refluxing, (2) change of operational conditions and (3) the implementation of new technologies. Experimental measurements and computer simulations show that the current plant´s main revenues are obtained from the electricity produced by the biogas engine (54%) and sales of the inactivated bio-solids for off-site biogas production (33%). The main expenditures are the discharge fee (39%), and transportation and handling of bio-solids (30%). Selective treatment of bio-solid streams strongly modifies the fate of COD and N compounds within the plant. In addition, it increases revenues (+3%), reduces cost (-9%) and liberates capacity in both activated sludge (+25%) and inactivation reactors (+50%). Better management of the buffer tank promotes heterotrophic denitrification instead of dissimilatory nitrate conversion to ammonia. In this way, 11% of the incoming nitrogen is removed within the anaerobic water line and does not overload the activated sludge reactors. Only a marginal increase in process performance is achieved when the anaerobic granular sludge reactor operates at full capacity. The latter reveals that influent biodegradability is the main limiting factor rather than volume. Usage of either NaOH or heat (instead of CaO) as inactivation agents allows anaerobic treatment of the reject water, which substantially benefits revenues derived from higher electricity recovery (+44%). However, there is a high toll paid on chemicals (+73%) or heat recovery (-19%) depending on the inactivation technology. In addition, partial nitration/Anammox and a better poly-aluminum chloride (PAC) dosage strategy is necessary to achieve acceptable (< 2%) N and P levels in the effluent. The scenarios are evaluated from a sustainability angle by using life cycle impact assessment (LCIA) in form of damage stressors grouped into three categories: human health, ecosystems quality, and resource scarcity. The presented decision support tool has been used by the biotech company involved in the study to support decision-making on how to handle future expansions.

Enhanced statistical evaluation of fluorescence properties to identify dissolved organic matter dynamics during river high-flow events

Fluorescence spectroscopy has become a widely used technique to characterize dissolved organic matter (DOM) and organic hazardous micro-pollutants in natural and human-influenced water bodies. Especially in rivers highly impacted by municipal and industrial wastewater treatment plants' effluents, the fluorescence signal at low-flow is mainly dominated by these discharges. At river high-flow, their influence decreases due to dilution effects, and at the same time, other compounds of DOM, stemming from diffuse inputs, can increase or even dominate. Therefore, whereas the analysis of DOM is little informative on the changing sources and pathways of emissions, fluorescence spectroscopy can enhance our understanding and our possibilities of monitoring such dynamics in river catchments. This paper analyzed samples from seven high-flow events in an Austrian river. Firstly, independent DOM components were discriminated using a parallel factor analysis (PARAFAC) to show the varying composition of DOM during different phases of high-flow events. Furthermore, partial least squares (PLS) and sparse PLS (sPLS) regression were applied to identify excitation and emission wavelengths, serving as proxy parameters for quantifying dissolved organic carbon (DOC) and chloride. The PLS models show the best prediction accuracy but use the entire excitation-emission matrix in exchange. In selecting predictors, the use of excitation and emission wavelengths adjusted via sPLS is superior to the extracted PARAFAC components. The sPLS model yields 16 wavelength combinations for DOC (RMSEsPLS = 0.41 mg L-1) and 18 wavelength combinations for chloride (RMSEsPLS = 2.21 mg L-1). In contrast to other established optical measurement methods, which require different calibrations for low- and high-flow conditions, these models based on sPLS succeed in quantifying those parameters across the entire range of flow conditions and events of various magnitudes with a relative precision of about 5 %. These results show how the application of multivariate statistical techniques enhances the exploitation of the information provided by fluorescence spectroscopy.

Economic performance index assessment of an industrial wastewater treatment plant in terms of the European Green Deal: effect of greenhouse gas emissions

Abstract This study aims to determine the effect of greenhouse gas (GHG) emissions on economic performance in terms of energy costs for an industrial wastewater treatment plant. Also, the mitigation of GHG emissions aimed at using process modification to obtain possible reductions in energy costs. Optimum energy consumptions were reported for the minimum GHG emission using the Data Envelopment Analysis (DEA) and Monte Carlo simulation model. In this paper, a new empirical approach has been developed depending on the GHG emissions for estimating the economic performance of the wastewater treatment plants. The results revealed that nitrous oxide (N2O) emissions led to the highest energy costs among direct emissions. In the second stage of the study, the effects of design conditions on GHG emissions and energy costs were investigated. If the aeration tank is operated at 24 h of hydraulic retention time (HRT) and 22 days of solid retention time (SRT), then, on average, 27, 27.9, and 30.7% of reduction in energy costs in terms of direct carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions, respectively, is observed in the plant. These reductions corresponded to approximately 17.33 €/kWh of cost-saving in this plant.

Short-term responses of the anammox process to Ni(II): nitrogen removal, mechanisms and inhibition recovery

Anaerobic ammonia oxidizing (anammox) has already been recognized as an innovative and economical nitrogen removal technology. However, the effect of heavy metals on anammox bacteria in aquatic ecosystem remains largely unknown. Ni(II) is a common kind of heavy metals detected in industrial wastewater and municipal sewage treatment plants. Hence, the responses of the anammox process to Ni(II) were studied here. The results showed that anammox was the dominant reaction with Ni(II) concentrations no more than 25 mg/L. 1 mg/L of Ni(II) addition promoted nitrogen removal by anammox. The higher the Ni(II) concentrations and longer exposure time, the more inhibition for anammox bacteria was gotten. The IC50 of Ni(II) to anammox was determined as 83.86 mg/L by an exponential regression equation. The inhibition of Ni(II) on anammox activity was mainly attributed to intracellular accumulation Ni(II) inhibition to HDH activity. Two times increase of IC50 after 4 times circles of domestication suggests multiple intermittent domestication can increase the tolerance of anammox bacteria to Ni(II). EDTA washing can eliminate the inhibition of anammox activity by Ni(II) with Ni(II) addition no more than 25 mg/L.

Simulation of an Industrial Wastewater Treatment Plant by Up-flow Anaerobic Fixed Bed Bioreactor Based on an Artificial Neural Network

Given the variable nature of industrial wastewaters, the appropriate operation of an industrial wastewater treatment plant (WWTP) is a prerequisite for keeping process stability at ideal conditions. In this respect, an artificial neural network (ANN) can be a powerful device for the prediction of treatment performance. This study assessed some qualitative parameters of industrial wastewater (Amol Industrial Estate) during a one-year operating period. The wastewater treatment process consisted of an equalization tank, up-flow anaerobic fixed bed (UAFB) bioreactor, activated sludge tank, sedimentation tank, and chlorination basin. The ANN was utilized to estimate the system efficiency of the UAFB process. The outcomes demonstrated an extraordinary arrangement between the real and simulated data (R2&gt;0.8). This model supplied a proper device for forecasting the implementation of WWTPs. Continuous checking elements could be used for the simulation of wastewater specifications.

An Evidence-Based Survey on Full-Scale Membrane Biological Reactors: Main Technical Features and Operational Aspects

This paper presents the results of a survey on full-scale membrane biological reactors (MBRs) wastewater treatment plants (WWTPs) in Italy. Alongside the main technical characteristics of the Italian MBR plants, the opinions of the plant managers on the operational advantages and disadvantages are described. As reported by the MBR technology suppliers, approximately 290 MBR municipal or industrial WWTPs are in operation in Italy, out of which 242 were studied in this survey. Data from more than one hundred municipal WWTPs were collected; these account for a total capacity of about 2,000,000 population equivalent (PE), which corresponds to 3% of the total organic load treated by the Italian WWTPs with secondary and advanced treatment. Usually, small installations adopt the flat-sheet rather than hollow-fiber membrane configuration. The main reasons why the MBR technology has been preferred to other options are its potential to be used for increasing the treatment capacity of existing plants and its compactness. Moreover, the followed operational advantages have been highlighted: easiness to comply with the discharge limits, removal of pathogens without specific disinfection units, possibility of internal reuse of the effluent, and process automation. Membrane fouling and plant shutdown have been recorded as the most relevant troubles, the last one indeed occurring only occasionally or rarely.

Advanced treatment of industrial estate effluent using ozone-membrane processes based on optimized random forest model

This study aimed to survey ozone-membrane processes for advanced treatment of secondary effluent in the industrial estate wastewater treatment plant. The performance of a pilot-scale system combining chemical treatment (coagulation, flocculation, sedimentation), sand filtration, ultrafiltration, activated carbon, and reverse osmosis were evaluated without and with ozonation at three different points of the set up. Ozone at the reaction time of 30 min and concentration of 24 ppm was injected before chemical treatment, before UF and before RO. UV254, COD, TOC, TSS, TDS, pH, turbidity and ozone efficiency were evaluated. For estimating the value of UV254, a random forest (RF) model was presented. The model uses supervised learning to estimate UV254 from an input vector consisting of step, location pH, temperature, electrical conductivity, and turbidity. The residue of organic matters, as UV254, that enter the membrane systems (UF and RO) were 0.125, 0.080, and 0.198 cm−1, respectively, which is desirable compared to the ozone-free state which is equal to 0.251 cm−1. Ozonation before UF, showed the lowest value (0.080 cm−1). TOC concentrations in the step of ozonation before UF were 12.1, 11.2, 10.8, 7.7, and 0.75 mg/l after SF, ozonation, UF, AC, and RO, respectively. Estimation of UV254 using RF-BO method represents MAE, MSE, and RMSE indexes equal to 0.01632, 0.00044191, and 0.021022, respectively. The results showed better efficiency of ozone injection before UF, compared to the other two cases. In the UV254 estimation section, the model shows enhanced accuracy in terms of error indexes in comparison with SVM-BO and GPR-BO methods.

Environmental and economic performances of incorporating Fenton-based processes into traditional sludge management systems

Municipal and industrial wastewater treatment plants produce a tremendous amount of sludge containing organic and toxic components. One of the advanced oxidation processes (AOP) - Fenton process has demonstrated great prospect in reduction of sludge organics and toxicity. Fenton pretreatment could ameliorate the sludge dewaterability and biodegradability for anaerobic digestion (AD) process, and enhance the sludge lower heating value for incineration process, thus stimulating sludge dewatering, reduction and energy recovery. However, doubts remain about whether the incorporation of the Fenton process into the traditional sludge management systems brings environmental benefits. Hence, a life cycle environmental impact calculation model was established for sludge with various organic contents (60%, 70%, 80%) under the effect of Fenton and US/UV/Electro-Fenton processes. Noteworthy mitigation of environmental load was observed for the Fenton process coupled with incineration system, which involves high dewatering demand. Conversely, as for the AD system with high biomass transformation rate, Fenton process failed to attain the assumed promotion of environmental benefit. Hydrogen peroxide (H2O2) prominently attributed to the weakness of Fenton process combined with AD (F-AD) scenario, compared with the AD scenario in terms of environmental impact. Summarily, the F-AD scenario acts as the preponderant system when weighing up the pros and cons of environmental impact, energy balance and life cycle cost. Contrary to the mainstream view, the proven technical advantages of Fenton process cannot compensate for the additional environmental loads in the life cycle of sludge. It provides valuable reflection for environmental managers and scholars that we should be more cautious in the application of cutting-edge technologies.

Effect of controlled aeration on COD and nitrogen removal in aerated constructed wetlands used for effluent polishing

Aerated wetland (AW) technology is typically used in high oxygen demand situations. This study however investigated its applicability for further polishing of effluents of both a municipal and an industrial wastewater treatment plant. Different aeration and pollutant removal strategies were tested, all under high hydraulic loading rate conditions (0.69 m3.m−2.d−1, 12h hydraulic retention time). The experiments were done on two 350 m² horizontal subsurface flow constructed wetlands (HSSF CW), filled with expanded clay aggregates (Argex™) and planted with common reed (Phragmites australis). Each CW was divided into three equal zones, each equipped with forced bed aeration (FBA™). For this study, continuous (100% on) and time-based (50%-time on/off) aeration were compared versus set dissolved oxygen levels controlled by oxygen sensors (3–4, 2–3 and 1–2 mgO2. L−1 in each zone, and 2–3 mgO2. L−1 in zone 1 and no aeration in zones 2 and 3, designated as 2–3/0/0). Results showed near 100% nitrification for all aeration regimes. Chemical oxygen demand (COD) removal was between 18% and 33% during high aeration (100%, 50%, 3–4 and 2–3 mgO2. L−1) but was reduced (1–15%) during the most limiting aeration modes (1–2 and 2–3/0/0 mgO2. L−1). Denitrification was limited for municipal effluent, however, reasonable NO3-N removal (31–72%) was noted for industrial effluent. The optimal balance between removal efficiency and energy consumption was found to be for the 2–3 mgO2. L−1 aeration setting, consuming 6.9–11.2 Wh.m−3. The outcomes of this study can be helpful for implementing aerated CWs as a tertiary treatment.

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.

Comparison of COD and TOC in influents and effluents of six industrial wastewater treatment plants in Korea

Objectives : This study compared the CODMn and TOC concentrations of the influent and effluent from six industrial wastewater treatment plants (WWTPs) and the wastewater from manufacturing facilities in the industrial complexes, and to understand the correlation between the two indicators.Methods : The sampling campaigns were performed four times at each WWTP for both influent and effluent. Water quality surveys were also conducted to assess the characteristics of organic matter in the wastewater from the manufacturing facilities. A total of 272 facilities including manufacturing, non-manufacturing, and miscellaneous manufacturing units were surveyed. Results and Discussion : The CODMn/TOC ratios of the influent and the effluent of the WWTPs ranged from 0.78 to 1.79 (average 1.19) and 0.94 to 1.58 (average 1.20), respectively. The ratio of CODMn/TOC ratio in the wastewater from the manufacturing facilities was 1.06~1.22 (average 1.12). Industries with high R2 values for the CODMn/TOC ratios included rubber and plastics manufacturing (CODMn/TOC = 1.17), nonferrous metals manufacturing (CODMn/TOC = 0.94), medical materials and pharmaceutical manufacturing (CODMn/TOC = 0.98), and chemicals manufacturing (CODMn/TOC = 1.27).Conclusion : CODMn/TOC ratios of the influent and effluent of the six plants and the wastewater from manufacturing facilities varied in different ranges for each WWTP, with an average value of 1.12. The results of this study can be used as basic information to manage the effluent water quality of the WWTPs.