Advanced Wastewater Treatment Processes Research Articles

Change of Sludge Denitrification and Nitrification Rate according to the Operating Conditions in Advanced Wastewater Treatment Processes

Change of Sludge Denitrification and Nitrification Rate according to the Operating Conditions in Advanced Wastewater Treatment Processes

Integrating cost-effective microbial fuel cells and energy-efficient capacitive deionization for advanced domestic wastewater treatment

In the microbial fuel cells (MFCs) driven capacitive deionization (CDI) process, the electricity generated from MFCs can be utilized for downstream deionization processes in the CDI cell. However, due to the typical configuration of MFCs, i.e., anaerobic anode and aerobic cathode compartments, the MFC effluent still contains various ionic pollutants, e.g., NO3− and PO43−. In this study, we present the proof-of-concept of an integrated MFC-CDI process for advanced wastewater treatment: the cost-effective continuous-flow MFCs perform as secondary treatment for organic carbon and ammonium removal, electricity production; the energy-efficient CDI cell works as the tertiary treatment to enhance the purification and desalination of domestic wastewater effluent. The results indicated that approximately 90% of the chemical oxygen demand (COD) and ammonium were removed in the MFCs. CDI, powered by connecting two MFCs in parallel and associated with a potential of 0.49V, could subsequently remove multi-ionic species from the MFC-treated effluent. More specifically, nutrient ions (NO3− and PO43−) can be electrostatically removed by the CDI process. These results demonstrated that the integrated MFC-CDI technology, which harvested energy from wastewater, held great potential to be an advanced, energy-saving purification process for the simultaneous removal of carbonaceous pollutants, improved nutrient removal, and further electrosorptive desalination of domestic wastewater treatment, in order to achieve a sustainable water-energy system. They also showed that, in addition to effluent quality improvement, the tertiary electrosorption of CDI played a significant role in the stability of effluent quality so as to dampen variations in the quality of secondary-treated effluent.

Occurrence of phthalates in aquatic environment and their removal during wastewater treatment processes: a review.

Phthalates are plasticizers and are concerned environmental endocrine-disrupting compounds. Due to their extensive usage in plastic manufacturing and personal care products as well as the potential to leach out from these products, phthalates have been detected in various aquatic environments including drinking water, groundwater, surface water, and wastewater. The primary source of their environmental occurrence is the discharge of phthalate-laden wastewater and sludge. This review focuses on recent knowledge on the occurrence of phthalate in different aquatic environments and their fate in conventional and advanced wastewater treatment processes. This review also summarizes recent advances in biological removal and degradation mechanisms of phthalates, identifies knowledge gaps, and suggests future research directions.

Improvement of virus removal by pilot-scale coagulation-ultrafiltration process for wastewater reclamation: Effect of optimization of pH in secondary effluent

Reclaimed water (i.e., reused advanced-treated wastewater) offers an alternative water resource. To reduce the health risks associated with its use, efficient virus removal such as with advanced wastewater treatment processes is important. Virus removal by coagulation followed by ultrafiltration (UF) for the treatment of drinking water has been well examined. But its efficacy in wastewater reclamation purpose using secondary treated effluent (SE) from wastewater treatment plant (WWTP) as feed water is unclear. Here, we optimized the virus removal efficiency of coagulation-UF in pilot-scale wastewater reclamation plants using SE as feed water, using the F-specific RNA bacteriophage MS2 as a model virus, at two wastewater treatment plants in Japan. We investigated how using coagulation as a pretreatment for UF improved virus removal efficiency. The efficiency varied greatly between SEs. To reveal the cause of the variation, we conducted laboratory-scale batch coagulation experiments. The efficiency of viral coagulation was negatively correlated with the concentration of dissolved organic matter in the feed water. The optimum pH for coagulation differed between SEs, and the efficiency of coagulation could be dramatically improved by optimizing the pH. We confirmed that the virus removal efficiency in the pilot-scale facility actually could be improved by adjusting the pH. In addition, we confirmed that coagulation–sedimentation-UF with pH adjustment could operate stably for more than 30 days at the pilot scale, with a high virus removal rate. Thus, the wastewater reclamation process described here offers promise in terms of reduced health risks and practical operation.

Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants

Advanced wastewater treatment processes and novel technologies are adopted to improve nutrient removal from wastewater so as to meet stringent discharge standards. Municipal wastewater treatment plants are one of the major contributors to the increase in the global greenhouse gas (GHG) emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarises the recent development in studies of greenhouse gases’ (CH4 and N2O) generation and emission in municipal wastewater treatment plants. It introduces the concepts of direct emission and indirect emission, and the mechanisms of GHG generations in wastewater treatment plants’ processing units. The book explicitly describes the techniques used to quantify direct GHG emissions in wastewater treatment plants and the protocol used by the Intergovernmental Panel on Climate Change (IPCC) to estimate GHG emission due to wastewater treatment in the national GHG inventory. Finally, the book explains the life cycle assessment (LCA) methodology on GHG emissions in consideration of the energy and chemical usage in municipal wastewater treatment plants. In addition, the strategies to mitigate GHG emissions are discussed. The book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in municipal wastewater treatment plants and industrial wastewater treatment processes. It is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas; for researchers in the relevant areas; and for professional reference by water professionals, government policy makers, and research institutes. ISBN: 9781780406305 (Print) ISBN: 9781780406312 (eBook) ISBN: 9781780409054 (ePUB)

Formation of bioactive transformation products during glucocorticoid chlorination

Glucocorticoid (GC) release into the environment has led to widespread detection of glucocorticoid receptor (GR) activity in water resources that has been shown to persist throughout conventional and some advanced wastewater treatment processes.

Integrated Evaluation Concept to Assess the Efficacy of Advanced Wastewater Treatment Processes for the Elimination of Micropollutants and Pathogens.

A multidisciplinary concept has been developed to compare advanced wastewater treatment processes for their efficacy of eliminating micropollutants and pathogens. The concept is based on (i) the removal/formation of selected indicator substances and their transformation products (TPs), (ii) the assessment of ecotoxicity via in vitro tests, and (iii) the removal of pathogens and antibiotic resistant bacteria. It includes substances passing biological wastewater treatment plants regulated or proposed to be regulated in the European Water Framework Directive, TPs formed in biological processes or during ozonation, agonistic/antagonistic endocrine activities, mutagenic/genotoxic activities, cytotoxic activities, further activities like neurotoxicity as well as antibiotics resistance genes, and taxonomic gene markers for pathogens. At a pilot plant, ozonation of conventionally treated wastewater resulted in the removal of micropollutants and pathogens and the reduction of estrogenic effects, whereas the in vitro mutagenicity increased. Subsequent post-treatment of the ozonated water by granular activated carbon (GAC) significantly reduced the mutagenic effects as well as the concentrations of remaining micropollutants, whereas this was not the case for biofiltration. The results demonstrate the suitability of the evaluation concept to assess processes of advanced wastewater treatment including ozonation and GAC by considering chemical, ecotoxicological, and microbiological parameters.

An advanced oxidation process for wastewater treatment to reduce the ecological burden from pharmacotherapy and the agricultural use of pesticides

The presence of pharmaceuticals and pesticides in the environment has been frequently confirmed and has been recognized as a potential threat to the environment. This paper describes an advanced wastewater treatment process based on the electrochemical oxidation of pollutants, and the development of a sensitive analytical method to monitor the analytes in wastewater samples comprised of solid phase extraction followed by LC–MS/MS analysis. The analytical method was successfully validated and achieved low limits of quantification (2.5–12.5ng/L).In our survey of some Slovenian wastewater samples, the occurrence of seven compounds from the list of ten monitored pollutants was confirmed and quantified. Bisoprolol, carbamazepine, ciprofloxacin, and metoprolol were determined in every assayed sample, while diclofenac reached the highest concentration (2μg/L). Therefore, under laboratory conditions the degradation efficiency of investigated compounds by various electrode materials, including boron-doped diamond (BDD), mixed metal oxide (MMO), platinum electrode, and high voltage sparks (HVS) were tested. The applicability of methodologies was evaluated on a synthetic mixture comprised of eight frequently prescribed pharmaceuticals (bisoprolol, carbamazepine, ciprofloxacin, clofibric acid, diclofenac, fluoxetine, imatinib and metoprolol) and two pesticides (atrazine, simazine). The BDD and MMO electrodes showed >85% degradation in 60min of treatment for the majority of the compounds, while the platinum electrode and HVS revealed low overall degradation efficiency. In addition, the BDD electrodes demonstrated an operational efficiency up to 70% also in a complex matrix of wastewater samples.Based on our observations of the prototype electrolytic cell degradation efficiency of some pollutants commonly presents in wastewaters, one can assume that this new technology could be a viable and feasible option to upgrade existing wastewater treatment plants in order to achieve a significantly greater cleaning efficiency, and to lessen the ecological burden.

Elimination of micropollutants and transformation products from a wastewater treatment plant effluent through pilot scale ozonation followed by various activated carbon and biological filters

Conventional wastewater treatment plants are ineffective in removing a broad range of micropollutants, resulting in the release of these compounds into the aquatic environment, including natural drinking water resources. Ozonation is a suitable treatment process for micropollutant removal, although, currently, little is known about the formation, behavior, and removal of transformation products (TP) formed during ozonation. We investigated the elimination of 30 selected micropollutants (pharmaceuticals, X-ray contrast media, industrial chemicals, and TP) by biological treatment coupled with ozonation and, subsequently, in parallel with two biological filters (BF) or granular activated carbon (GAC) filters. The selected micropollutants were removed to very different extents during the conventional biological wastewater treatment process. Ozonation (specific ozone consumption: 0.87 ± 0.29 gO3 gDOC−1, hydraulic retention time: 17 ± 3 min) eliminated a large number of the investigated micropollutants. Although 11 micropollutants could still be detected after ozonation, most of these were eliminated in subsequent GAC filtration at bed volumes (BV) of approximately 25,000 m3 m−3. In contrast, no additional removal of micropollutants was achieved in the BF. Ozonation of the analgesic tramadol led to the formation of tramadol-N-oxide that is effectively eliminated by GAC filters, but not by BF. For the antiviral drug acyclovir, the formation of carboxy-acyclovir was observed during activated sludge treatment, with an average concentration of 3.4 ± 1.4 μg L−1 detected in effluent samples. Subsequent ozonation resulted in the complete elimination of carboxy-acyclovir and led to the formation of N-(4-carbamoyl-2-imino-5-oxo imidazolidin)-formamido-N-methoxyacetetic acid (COFA; average concentration: 2.6 ± 1.0 μg L−1). Neither the BF nor the GAC filters were able to remove COFA. These results highlight the importance of considering TP in the evaluation of advanced wastewater treatment processes. The results further indicate that post-treatment of ozonated wastewater with GAC filtration seems to be more suitable than BF, due to the sorption of formed TP to the activated carbon.

Application of dissolved air flotation (DAF) with coagulation process for treatment of phosphorus within permeate of membrane bioreactor (MBR)

It is well known that eutrophication is one of the main issues with regard to environmental pollution and that phosphorus is the most critical among various nutrients. Consequently, effluent water quality of wastewater treatment plants has been recently reinforced in Korea. Many studies have been made on membrane bioreactor (MBR) processes, some of the more advanced wastewater treatment processes. However, MBR processes are relatively vulnerable to biological phosphorus treatment in comparison with conventional activated sludge processes. Alternately, dissolved air flotation (DAF) processes were applied as post-treatment of MBR processes in order to decrease T-P concentration of the final effluent. It was observed that T-P removal efficiency was 51.2% and that T-P concentration of the final effluent ranged from 0.49 to 1.62 mg/L with addition of 15 mg/L of alum to the rapid mixing reactor of DAF processes. The next step includes the addition of anionic polymers and bentonite to slow and rapid mixing tanks of DAF processes, respectively, to improve phosphorus removal efficiencies. Although T-P removal efficiency increased significantly from 51.2 to 78%, T-P concentration of effluent was observed between 0.38 and 0.96 mg/L. Lastly, the MBR process was controlled by adding a low concentration of alum to an aerobic tank and influent under 1 ± 0.3 mg/L of T-P. While T-P removal efficiency was around 80% in both 7 and 10 mg/L of alum, most measured values were under 0.2 mg/L except for several days of measurement. This indicates the potential of DAF processes for removing phosphorus as post-treatment of MBR.

Enhanced nitrogen and phosphorus removal by an advanced simultaneous sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal wastewater treatment process

An advanced wastewater treatment process (SIPER) was developed to simultaneously decrease sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The feasibility of simultaneous enhanced nutrient removal along with sludge reduction as well as the potential for enhanced nutrient removal via this process were further evaluated. The results showed that the denitrification potential of the supernatant of alkaline-treated sludge was higher than that of the influent. The system COD and VFA were increased by 23.0% and 68.2%, respectively, after the return of alkaline-treated sludge as an internal C-source, and the internal C-source contributed 24.1% of the total C-source. A total of 74.5% of phosphorus from wastewater was recovered as a usable chemical crystalline product. The nitrogen and phosphorus removal were improved by 19.6% and 23.6%, respectively, after incorporation of the side-stream system. Sludge minimization and excellent nutrient removal were successfully coupled in the SIPER process.

Holistic Assessment of Trace Organic Compounds (TOrC) in Wastewater Treatment

A study of trace organic compound (TOrC) reactivity to selected, advanced wastewater treatment processes was conducted as part of a demonstration-scale pilot study. The pilot facilities consisted of a biological nitrogen removal (BNR) activated sludge treatment process, parallel membrane and granular media filtration processes and a biologically active filter preceded by ozone treatment, and three parallel disinfection processes: free chlorine, ozone, and UV irradiation. Twelve trace organic indicator compounds were selected to represent the treatability of a breadth of compounds. Measurements of TOrC concentrations entering and exiting each unit process were made over a period of nine months, under a range of operating conditions to assess the treatability of each compound by each process. Comparisons were made to TOrC treatability through the existing full scale plant, a high purity oxygen activated sludge (HPOAS) secondary treatment plant using chloramination for disinfection. Eight of the twelve studied indicator TOrCs were reduced through the BNR process. Removals through the BNR process were more effective than removals through the HPOAS process, likely owing to longer solids retention time (SRT) and higher mixed liquor suspended solids (MLSS) concentration in the BNR process providing more bio-oxidation capacity than in the HPOAS process. Neither membrane nor granular media filtration was effective in reducing TOrCs, implying TOrCs are not particle associated. Many of the TOrCs were reduced by ozone treatment preceding biologically active filtration. The biologically active filter was not effective at reducing TOrCs, with the exception of NDMA, which was formed during ozonation, but then reduced through the bio-filter. Post-filtration disinfection processes had varying degrees of effectiveness reducing TOrCs, with ozone being most effective, followed by chlorine and UV. This title belongs to WERF Research Report Series . ISBN: 9781780405179 (eBook)

Microbial and metabolic characterization of a denitrifying phosphorus-uptake/side stream phosphorus removal system for treating domestic sewage.

In this study, an advanced wastewater treatment process, the denitrifying phosphorus/side stream phosphorus removal system (DPR-Phostrip), was developed for the purpose of enhancing denitrifying phosphorus removal. The enrichment of denitrifying phosphorus-accumulating organisms (DPAOs) and the microbial community structure of DPR-Phostrip were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and the metabolic activity of seed sludge and activated sludge collected after 55 days of operation were evaluated by Biolog™ analysis. This experimental study of DPR-Phostrip operation showed that nutrients were removed effectively, and denitrifying phosphorus removal was observed during the pre-anoxic period. PCR-DGGE analysis indicated that DPR-Phostrip supported DPAO growth while inhibiting PAOs and GAOs. The major dominant species in DPR-Phostrip were Bacteroidetes bacterium, Saprospiraceae bacterium, and Chloroflexi bacterium. Moreover, the functional diversity indices calculated on the basis of Biolog analysis indicated that DPR-Phostrip had almost no effect on microbial community diversity but was associated with a shift in the dominant species, which confirms the results of the PCR-DGGE analysis. The results for average well color development, calculated via Biolog analysis, showed that DPR-Phostrip had a little impact on the metabolic activity of sludge. Further principal component analysis suggested that the ability to utilize low-molecular-weight organic compounds was reduced in DPR-Phostrip.

Occurrence and fate of antibiotics in advanced wastewater treatment facilities and receiving rivers in Beijing, China

The occurrence and removal of 13 antibiotics were investigated in five wastewater treatment plants (WWTPs) with advanced wastewater treatment processes in Beijing, China. Most of the target antibiotics were detected in the secondary and tertiary effluents, with the concentrations of 4.8–1106.0 and 0.3–505.0 ng·L−1. Fluoroquinolone antibiotics showed relatively high concentrations in all samples (782–1814 ng·L−1). Different tertiary treatment processes showed discrepant antibiotics removal performances. Ozonation process was found more effective in removing target antibiotics compared to the coagulation-flocculation-sedimentation process and sand filtration process. Investigation of the target antibiotics in three typical urban rivers in Beijing was carried out to understand antibiotics occurrence in surface water environment. Eight antibiotics were detected in the studied rivers, with highest concentration of antibiotics in the river which was mainly replenished by reclaimed water. This study showed the necessity of employing more effective advanced treatment facilities to further reduce the discharge amount of antibiotics.

Phosphate removal from aqueous solution by Donnan dialysis with anion-exchange membrane

The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated. The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential. Under the conditions of influent phosphate of 2.0 mg/L, counterion(Cl−) concentration of 0.1 mol/L, stirring speed of 500 r/min and phase temperature of 298 K, the removal of phosphate achieves 70.0%. Decreasing counterion concentration has little influence on the removal of phosphate, but phosphate amount in anion-exchange membrane increases significantly. With the increase of stirring speed and phase temperature, the removal efficiency of phosphate greatly is improved. Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution (pH=3.0) decreases the removal of phosphate. Transport of phosphate is also accompanied by change of pH value of feed solution. In consequence, it might be a promise potential process for phosphate advanced wastewater treatment, especially in the area where high salted nature water can be utilized.

이단유로 축전식 탈염공정의 하수고도처리 적용가능성 평가

This study demonstrates a double-path CDI as an alternative of advanced wastewater treatment process. While the CDI typically consists of many pairs of electrodes connected in parallel, the new double-path CDI is designed to have series flow path by dividing the module into two stages. The CFD model showed that the double-path had uniform flow distribution with higher velocity and less dead zone compared with the single-path. However, the double-path was predicted to have higher pressure drop(0.7 bar) compared the single-path (0.4 bar). From the unit cell test, the highest TDS removal efficiencies of single- and double-path were up to 88% and 91%, respectively. The rate of increase in pressure drop with an increase of flow rate was higher in double-path than single-path. At 70 mL/min of flow rate, the pressure drop of double-path was 1.67 bar, which was two times higher than single-path. When the electrode spacing was increased from 100 to , the pressure drop of double-path decreased from 1.67 to 0.87 bar, while there was little difference in TDS removal. When proto type double-path CDI was operated using sewage water, TDS, -N, -N and -P removal efficiencies were up to 78%, 50%, 93% and 50%, respectively.

Combined biologic aerated filter and sulfur/ceramisite autotrophic denitrification for advanced wastewater nitrogen removal at low temperatures

An innovative advanced wastewater treatment process combining biologic aerated filter (BAF) and sulfur/ceramisite-based autotrophic denitrification (SCAD) for reliable removal of nitrogen was proposed in this paper. In SCAD reactor, ceramisite was used as filter and Ca (HCO3)2 was used for supplying alkalinity and carbon source. The BAF-SCAD was used to treat the secondary treatment effluent. The performance of this process was investigated, and the impact of temperature on nitrogen removal was studied. Results showed that the combined system was effective in nitrogen removal even at low temperatures (8 °C). Removal of total nitrogen (TN), NH4+ -N, NO3− -N reached above 90% at room temperature. Nitrification was affected by the temperature and nitrification at low temperature (8 °C) was a limiting factor for TN removal. However, denitrification was not impacted by the temperature and the removal of NO3− -N maintained 98% during the experimental period. The reason of effective denitrification at low temperature might be the use of easily dissolved Ca(HCO3)2 and high-flux ceramisite, which solved the problem of low mass transfer efficiency at low temperatures. Besides, vast surface area of sulfur with diameter of 2–6 mm enhanced the rate of microbial utilization. The removal of nitrate companied with the production of SO42−, and the average concentration of SO42− was about 240 mg·L−1. These findings would be beneficial for the application of this process to nitrogen removal especially in the winter and cold regions.

PAC를 이용한 하수의 고도처리공정에서의 인 제거

PAC를 이용한 하수의 고도처리공정에서의 인 제거

Anode-biofilm electron transfer behavior and wastewater treatment under different operational modes of bioelectrochemical system

Anode-biofilm electron transfer behavior was investigated during the advanced wastewater treatment process by three bioelectrochemical systems (BESs): microbial fuel cell (MFC), MFC operated under short circuit condition (MSC), and microbial electrolysis cell (MEC). Under different operational modes, current produced by the anode biofilm varied from 0.92, 4.15 to 8.21mA in the sequence of MFC, MSC and MEC, respectively. The cyclic voltammetry test on the anode biofilm suggested that the current generation was achieved via various bioelectroactive species with formal potentials at -0.473, -0.402 and -0.345V (vs. SCE). Gibbs free energy and charge transfer resistance data demonstrated that different amounts of available bioelectroactive species functioned in different BESs. The comparative investigation among MFC, MSC and MEC suggested that MEC was the only feasible operational mode for advanced wastewater treatment, because of its superior current generation capability.

Occurrence of earthy and musty odor compounds (geosmin, 2-methylisoborneol and 2,4,6-trichloroanisole) in biologically treated wastewater

The concentrations of earthy and musty odor compounds (2-methylisoborneol (2-MIB), geosmin and 2,4,6-trichloroanisole (TCA)) in treated wastewater were measured. Concentrations of 2,4,6-TCA (4.3-37.7 ng/L) and geosmin (3.7-42.2 ng/L) higher than their odor thresholds were detected for effluents from large-scale treatment plants. The effluent from a small-scale wastewater plant treating toilet and kitchen wastewater contained the target earthy and musty odor compounds below the odor thresholds. The ozonation applied as an advanced wastewater treatment process was considerably more effective for the removal of 2,4,6-TCA than for the removal of 2-MIB and geosmin. The measured concentrations of 2,4,6-TCA in river environments without the influence of large-scale wastewater effluents were less than the odor threshold.