Wastewater Treatment Plants In Korea Research Articles

New findings on the occurrence, removal, and risk assessment of nonylphenol and octylphenol in industrial wastewater treatment plants in Korea

Nonylphenol (NP) and octylphenol (OP), extensively used in industries, can disrupt the human endocrine system and cause significant ecological toxicity. Therefore, in this study, we aimed to reveal the occurrence and removal characteristics of NP and OP in 30 industrial wastewater treatment plants (IWWTPs). Specifically, this study focused on 13 NP isomers that have not been previously reported. Additionally, the potential environmental risk of NP and OP discharged from IWWTPs was assessed using a minimum dilution factor (MDF), proposed for the first time in this study. We showed that the concentration and proportion of the isomer NP11 were higher than those of the other isomers in the IWWTP influents and effluents. We also identified an activated sludge-activated carbon adsorption process suitable for removing NP and OP. Finally, we proposed the MDF value of 11 for the potential environmental risk assessment of NP and OP, revealing that OP poses a higher risk than NP when discharged into surface water. These findings underscore the importance of focusing on the isomer NP11 and OP in IWWTPs.

In vitro bioanalytical assessment of the occurrence and removal of bioactive chemicals in municipal wastewater treatment plants in Korea

Effluents of wastewater treatment plants (WWTPs) contain various organic micropollutants, some of which can exert negative effects on the quality of receiving waters or drinking water sources. This study monitored two full-scale WWTPs in Korea for the occurrence and removal of bioactive chemicals for a one-year period using a battery of in vitro bioassays as a complementary approach to chemical analysis. Bioassays covering different endpoints were employed, such as hormone receptor activation (AR and ERα), xenobiotic metabolism (PAH and PXR), oxidative stress response (Nrf2), and cytotoxicity. The WWTP influents showed AR, ERα, and PAH activities at ng/L - μg/L and PXR and Nrf2 activities at μg/L - mg/L as bioanalytical equivalent concentrations of a reference compound for each bioassay. These bioactivities decreased along with the WWTP treatment train, with significant removals achieved by the secondary biological treatment processes. Cytotoxicity was observed only for some municipal wastewater (M-WWTP) influents but was below the limit of quantification for most cases. The influent and effluent bioactivities observed in this study were mostly comparable to those reported in other WWTPs in the literature. Comparison of the bioactivities with the effect-based trigger (EBT) values indicates that the impact of WWTP effluents on receiving water quality was low for most endpoints. For Nrf2, however, further investigation is required to evaluate the observed high bioactivities compared with the current EBT. The observed ERα activity could partly be explained by the presence of some steroid estrogens. Overall, our results contribute to an important database for the concentrations and removal efficiencies of bioactive chemicals in WWTPs and demonstrate bioassays as a useful tool for urban water quality monitoring.

New insights into the occurrence and removal of 36 pesticides in pesticide wastewater treatment plants in Korea

This study investigates the occurrence of 36 pesticides—including 33 that were monitored from 2007 to 2019 in Korean rivers—in wastewaters from pesticide manufacturing facilities (PMFs) and in 13 pesticide wastewater treatment plants (PWWTPs). Furthermore, an approach for the effective removal of these pesticides from pesticide wastewater (PW) is proposed. Among the 36 pesticides investigated, 32 were found to be present in the PMF wastewater and PWWTP influents (at concentrations ≤466.8 mg/L). In addition, 24 of the 36 pesticides were detected in PWWTP effluents, indicating that effluents are discharged without the complete removal of many pesticides. Moreover, the PWWTP effluent influences the presence of pesticides in river (confidence interval: ≥ 95%; p < 0.05). Although the chemical oxidation–activated sludge process is frequently recommended for the treatment of PWs, the findings from the current study indicate that an activated sludge–activated carbon adsorption process is more suitable for PW treatment due to its superior removal efficiency, treatment stability, and economic feasibility. Consequently, its application for the treatment of PWs can markedly decrease the levels of pesticides discharged into rivers.

Seasonal variation and spatial distribution of microplastics in tertiary wastewater treatment plant in South Korea

Wastewater treatment plant (WWTP) is proposed to be a point source of microplastics (MPs) that enter aquatic environments. Here, we quantified and characterized MPs down to 20 µm at a tertiary WWTP in Korea over a 1-year period. All wastewater contained MPs during the monitoring period, with concentrations ranging from 114 ± 17–216 ± 65 particles/L for influent and from 0.26 ± 0.29–0.48 ± 0.11 particles/L for effluent. MP abundance in the influents showed significant seasonal differences whereas a seasonal trend was not observed for the effluents, indicating a stable treatment performance (approx. 99.8%) of the WWTP. Spatial surveys of MP distribution in the WWTP showed that most MPs were removed by coagulation-sedimentation and rapid sand filtration, but some MPs still remained in the final effluent to generate the potential annual load of 2.9 × 109 particles and 0.54 kg into the rivers. These findings highlight the importance of long-term monitoring and MP mass quantification that would promote more accurate estimation of the MP load from WWTPs.

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.

New Insights into the Occurrence and Removal of 36 Pesticides in Wastewater Treatment Plants in Korea

New Insights into the Occurrence and Removal of 36 Pesticides in Wastewater Treatment Plants in Korea

Evaluation of nutrient bioextraction by seaweed and shellfish aquaculture in Korea

AbstractAlthough Korea is third in seaweed production and second in shellfish production globally, this is the first study evaluating ecosystem services of seaweed and shellfish aquaculture in Korea. The objective of this study is to evaluate nutrient bioextraction capacities of major seaweed and shellfish species aquacultured in Korea. C (C) removal of three major aquacultured seaweed species, Neopyropia yezoensis, Saccharina japonica, and Undaria pinnatifida were 24,247, 8,423, and 12,758 tons, respectively, in 2016. N (N) removal of these species was 4,088, 732, and 1,244 tons, respectively. The C and N removal of the Pacific oysters (Crassostrea gigas) were 14,693 and 1,050 tons, respectively. Manila clams (Venerupis philippinarum) removed 2,120 tons of C and 136.5 tons of N. Together, 161,846 tons of CO2 and 7,251 tons of N were removed by three major seaweed species and two shellfish species. These values are significant amounts, equivalent to 5.7% of CO2 and 8.6% of N discharged from all wastewater treatment plants in Korea. These results suggest that nutrient bioextraction by aquacultured seaweed and shellfish can be a cost efficient, affordable, and equitable solution for coastal nutrient management programs in Korea and elsewhere.

Spatial variation of pharmaceuticals in the unit processes of full-scale municipal wastewater treatment plants in Korea

Several reports have elucidated the removal of pharmaceutical residues in municipal wastewater treatment plants (WWTPs). However, there remains a need to determine the spatial distribution of pharmaceuticals in the unit processes of full-scale municipal WWTPs. Herein, spatial variations of fifteen pharmaceuticals in the unit processes of four full-scale municipal WWTPs were assessed by analyzing both solid and liquid samples. Furthermore, different pathways of each pharmaceutical such as biodegradation, adsorption, deconjugation, and electrostatic interaction were investigated. Pharmaceutical mass loading were measured at various points for the different unit process and evaluated using liquid chromatography-tandem mass spectrometry. The average mass loading of acetaminophen and caffeine decreased tremendously in the first biological treatment process regardless of the process configuration. In contrast, a temporary increase was observed in the mass loading of ibuprofen in the anaerobic and/or anoxic processes, which was presumably caused by deconjugation. Additionally, the adverse effect of coagulation on ibuprofen removal was validated. The major removal mechanism for the selected antibiotics, except for sulfamethoxazole, was the adsorption by biosolids due to electrostatic interaction. Subsequently, a drastic decrease was observed in their mass loadings in the solid-liquid separation process of the WWTPs. The membrane bioreactor (MBR) shows excellent capability for mitigation of pharmaceuticals in municipal wastewater because it comprises a high concentration of biosolids that act as adsorbents. The evaluation of the spatial variations of the selected pharmaceuticals in different unit processes provides valuable information on their behavior and removal mechanisms.

Quantification of nosZ genes and transcripts in activated sludge microbiomes with novel group-specific qPCR methods validated with metagenomic analyses

Substantial N2O emission results from activated sludge nitrogen removal processes. N2O-reducing organisms possessing NosZ-type N2O reductases have been recognized to play crucial roles in suppressing emission of N2O produced in anoxic activated sludge via denitrification; however, which of the diverse nosZ-possessing organisms function as the major N2O sink in situ remains largely unknown. Here, nosZ genes and transcripts in wastewater microbiomes were analyzed with the group-specific qPCR assays designed de novo combining culture-based and computational approaches. A sewage sample was enriched in a batch reactor fed continuous stream of N2 containing 20-10,000 ppmv N2O with excess amount (10 mM) of acetate as the source of carbon and electrons, where 14 genera of potential N2O-reducers were identified. All available amino acid sequences of NosZ affiliated to these taxa were grouped into five subgroups (two clade I and three clade II groups), and primers/probe sets exclusively and comprehensively targeting the subgroups were designed and validated with in silico PCR. Four distinct activated sludge samples from three different wastewater treatment plants in Korea were analyzed with the qPCR assays and the results were validated with the shotgun metagenome analysis results. With these group-specific qPCR assays, the nosZ genes and transcripts of six additional activated sludge samples were analyzed and the results of the analyses clearly indicated the dominance of two clade II nosZ subgroups (Flavobacterium-like and Dechloromonas-like) among both nosZ gene and transcript pools.

National Reconnaissance Survey of Microplastics in Municipal Wastewater Treatment Plants in Korea.

Large quantities of microplastics are thought to be emitted to freshwater environments via wastewater treatment plants (WWTPs). To evaluate the occurrence of microplastics in Korean WWTPs, a nationwide study was conducted for the first time in 50 representative WWTPs with large treatment capacities. Grab sampling and laboratory filtration were used for influents, whereas in situ filtration using a custom-made sampling device was used for effluents. The filtrates were pretreated using wet peroxidation and density separation prior to the identification of microplastics with a dissection microscope and Fourier-transform infrared spectroscopy. Pooled analyses of the microplastics revealed that they were predominantly fragment-shaped, and thermoplastics and synthetic fibers were the dominant microplastic materials in WWTPs. The concentration ranged from 10 to 470 L-1 in influents and 0.004 to 0.51 L-1 in effluents. The removal efficiency of microplastics during wastewater treatment was calculated to be 98.7-99.99% in 31 WWTPs. Additionally, WWTPs using advanced phosphorus removal processes exhibited higher removal efficiency than those not implementing such processes. Power-law distribution was successful in describing microplastic particle sizes down to 100 μm, although it was not applicable for smaller particles. This comprehensive monitoring study provides information on the current level and characteristics of microplastics in WWTPs in Korea.

Contamination of Metal Elements in Livestock Wastewater Treatment Plants in Korea

Contamination of Metal Elements in Livestock Wastewater Treatment Plants in Korea

The capacity of wastewater treatment plants drives bacterial community structure and its assembly

Bacterial communities in wastewater treatment plants (WWTPs) affect plant functionality through their role in the removal of pollutants from wastewater. Bacterial communities vary extensively based on plant operating conditions and influent characteristics. The capacity of WWTPs can also affect the bacterial community via variations in the organic or nutrient composition of the influent. Despite the importance considering capacity, the characteristics that control bacterial community assembly are largely unknown. In this study, we discovered that bacterial communities in WWTPs in Korea and Vietnam, which differ remarkably in capacity, exhibit unique structures and interactions that are governed mainly by the capacity of WWTPs. Bacterial communities were analysed using 16S rRNA gene sequencing and exhibited clear differences between the two regions, with these differences being most pronounced in activated sludge. We found that capacity contributed the most to bacterial interactions and community structure, whereas other factors had less impact. Co-occurrence network analysis showed that microorganisms from high-capacity WWTPs are more interrelated than those from low-capacity WWTPs, which corresponds to the tighter clustering of bacterial communities in Korea. These results will contribute to the understanding of bacterial community assembly in activated sludge processing.

Activated sludge process diagnosis using advanced real-time monitoring equipment: activated sludge plant controller (ASP-CON)

The aim of this study is to evaluate a newly invented instrument, activated sludge plant controller (ASP-Con), and to optimize treatment processes by reducing energy consumption and saving costs in pursuance of achieving sustainable energy and water cycles. Although three hundred billion dollars of investment were put into the energy independence project to save energy and cost when operating wastewater treatment plant in Korea, it failed because the investments were allocated only to improvements of digester facilities, designs, and capacities. To propose a feasible optimization strategy for the wastewater treatment plant with minimal wastes, the ASP-Con was introduced and experimented in four major wastewater treatment plants in the Republic of Korea. This study identifies the optimal operating points for blower based on the oxygen uptake rate and dissolved oxygen measurement, and supported by ammonium measurements to run the plant efficiently in real time.

Occurrence and emission of phthalates and non-phthalate plasticizers in sludge from wastewater treatment plants in Korea.

Phthalates are endocrine-disrupting chemicals that cause adverse health effects in wildlife and humans. Due to domestic and global regulations of phthalates in commercial products, non-phthalate plasticizers (NPPs) have been introduced into industrial markets. Few studies have been conducted on the occurrence of phthalates and NPPs in sludge from wastewater treatment plants (WWTPs). In this study, sludge samples were collected from 40 WWTPs in Korea to investigate the occurrence, compositional profiles, and emission flux of phthalates and NPPs. Total concentrations of phthalates and NPPs in sludge ranged from 4.7 to 1400 (mean: 110) μg/g dry weight and from 0.17 to 780 (mean: 28.0) μg/g dry weight, respectively. Di(2-ethylhexyl)phthalate (DEHP) was a predominant compound, suggesting widespread consumption in Korea. Di(2-ethylhexyl)terephthalate (DEHT) was dominant in industrial sludge samples, whereas di-isononyl cyclohexane-1,2-dicarboxylate (DINCH) and trioctyl trimellitate (TOTM) were dominant in domestic sludge. This implies different consumption patterns of phthalate alternatives by industry and domestic activities. Concentrations of NPPs were significantly correlated with those of high-molecular-weight (HMW) phthalates, indicating that HMW phthalates were preferentially replaced by NPPs. The emission fluxes of phthalates via domestic WWTP activities were higher than those measured for industrial WWTPs, while the emission fluxes of NPPs via industrial WWTPs were higher than those found for domestic and industrial WWTPs. This indicates that phthalate emissions are associated with household activities, while NPP emissions are associated with industrial activities.

Pseudaminobacter granuli sp. nov., isolated from granules used in a wastewater treatment plant.

A Gram negative, aerobic, non-motile and rod-shaped bacterial strain designated as Gr-2T was isolated from granules used in a wastewater treatment plant in Korea, and its taxonomic position was investigated using a polyphasic approach. Strain Gr-2T grew at 18-37°C (optimum temperature, 30°C) and a pH of 6.0-8.0 (optimum pH, 7.0) on R2A agar medium. Based on 16S rRNA gene phylogeny, the novel strain showed a new branch within the genus Pseudaminobacter of the family Phyllobacteriaceae, and formed clusters with Pseudaminobacter defluvii THI 051T (98.9%) and Pseudaminobacter salicylatoxidans BN12T (98.7%). The G+C content of the genomic DNA was 63.6%. The predominant respiratory quinone was ubiquinone-10 (Q-10) and the major fatty acids were cyclo-C19:0 ω8c, C18:1 ω7c, and iso-C17:0. The overall polar lipid patterns of Gr-2T were similar to those determined for the other Pseudaminobacter species. DNA-DNA relatedness values between strain Gr-2T and its closest phylogenetically neighbors were below 18%. Strain Gr-2T could be differentiated genotypically and phenotypically from the recognized species of the genus Pseudaminobacter. The isolate therefore represents a novel species, for which the name Pseudaminobacter granuli sp. nov. is proposed with the type strain Gr-2T (=KACC 18877T =LMG 29567T).

Removal rate and releases of polybrominated diphenyl ethers in two wastewater treatment plants, Korea

Wastewater treatment plants (WWTPs) play an important role in minimizing the release of many pollutants into the environment. Nineteen congeners in two WWTPs in Korea were determined to investigate the occurrence and fate of polybrominated diphenyl ethers (PBDEs) during wastewater treatment processes. The concentration of total PBDEs was 69.6 and 183 ng/L in influent, which declined to 1.59 and 2.34 ng/L in the final effluent, respectively (Tongyeong and Jinhae WWTPs). PBDEs were found to exist mostly in the particulate phase of wastewater, which rendered sedimentation efficient for the removal of PBDEs. BDE-209 was the predominant congener in the influent and sludge. Most of the PBDEs entering the WWTPs presumably ended up in the sludge, with < 2% being discharged with the final effluent. According to the mass loading estimation, every day 2.55–9.29 g PBDEs entered the two WWTPs, 2.8–10.4 g were disposed to landfill sites in sludge form and 0.06–0.12 g were discharged to the surrounding water through final effluent, respectively. Preliminary results indicated that the ecological risk to organisms in soil exposed to PBDEs through the usage of sludge application to agricultural land was relatively low. To our knowledge, this study is the first to report on the removal efficiency of PBDEs in a WWTP in Korea.

A national discharge load of perfluoroalkyl acids derived from industrial wastewater treatment plants in Korea

Levels of 11 perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), were measured in wastewater (influent and effluent) and sludge samples collected from 25 industrial wastewater treatment plants (I-WWTPs) in five industrial sectors (chemicals, electronics, metals, paper, and textiles) in South Korea. The highest ∑11PFAAs concentrations were detected in the influent and effluent from the paper (median: 411ng/L) and textile (median: 106ng/L) industries, and PFOA and PFOS were the predominant PFAAs (49–66%) in wastewater. Exceptionally high levels of PFAAs were detected in the sludge associated with the electronics (median: 91.0ng/g) and chemical (median: 81.5ng/g) industries with PFOS being the predominant PFAA. The discharge loads of 11 PFAAs from I-WWTP were calculated that total discharge loads for the five industries were 0.146ton/yr. The textile industry had the highest discharge load with 0.055ton/yr (PFOA: 0.039ton/yr, PFOS: 0.010ton/yr). Municipal wastewater contributed more to the overall discharge of PFAAs (0.489ton/yr) due to the very small industrial wastewater discharge compared to municipal wastewater discharge, but the contribution of PFAAs from I-WWTPs cannot be ignored.

Distribution and seasonal occurrence of UV filters in rivers and wastewater treatment plants in Korea

The occurrence and distribution of eight UV filters benzophenone (BP), benzophenone-3 (BP-3), ethylhexyl methoxy cinnamate (EHMC), 4-methylbenzylidene camphor (4-MBC), 2-ethylhexyl 4-dimethylaminobenzoate (OD-PABA), 2-ethylhexyl salicylate (EHS), isoamyl benzoate, and benzyl cinnamate in eleven sites among three rivers, five sewage treatment plants (STPs), and four wastewater treatment plants (WWTPs) located in different parts of Korea was investigated. The total concentrations of UV filters in the three sampled seasons were 62.9–412ngL−1 (river), 417–5055ngL−1 (STP influent), 108–2201ngL−1 (STP effluent), 122–4154ngL−1 (WWTP influent), and 120–849ngL−1 (WWTP effluent). The concentration of the target pollutants in the influent of the treatment systems was directly proportional to the resident population density. A seasonal increase of >27% was observed in the total concentration of the UV filters in the rivers and influents of the treatment plants (TPs) during summer. BP, BP-3, EHMC, 4-MBC, and EHS were the most dominant, showing a distinct distribution pattern that was dependent on the effectiveness of the treatment process and properties of each compound. The concentrations of the UV filters were higher in the TPs influents than in the rivers, and the most dominant UV filters in the rivers were those with low removal rate. Although biological treatment processes favored the removal of the UV filter compounds in the TPs, complete removal was not achieved before discharge into the rivers.

National risk assessment of irrigation on farmland near wastewater treatment plants in Korea

There are more than 130 agricultural water sources that are located near wastewater treatment plants (WWTPS) in Korea. The majority of the stream flow in these farmlands is dependent on effluent from the WWTPS during the dry season. This explains the indirect or direct reuse of effluent from WWTPs. Most of the farm workers use the effluent without any additional treatment because they have a lack of knowledge regarding water reuse. In addition, insufficient consideration is given to health and hygiene safety. This study reviewed the safety issues in these farmlands. A total of 53 farmlands located near WWTPs were investigated to determine if farm workers used effluent as irrigation water on their paddy rice fields. Total coliform, fecal coliform, Escherichia coli (E. coli), and the concentration of some heavy metals in paddy water and soils were measured. Quantitative microbial and toxic risk assessment methods were used to review the safety of wastewater irrigation. E. coli concentrations were used to estimate the microbial risk of enteric disease in the paddy fields. The microbial risk was 5.9 × 10−4, which did not satisfy the minimum safety standards. Carcinogenic risk was 3.99 × 10−5 and non-carcinogenic risk was 6.34 × 10−1. These values were too high to be considered safe, even though the measurements of E. coli and some toxic metals were of short duration.

Emission of bisphenol analogues including bisphenol A and bisphenol F from wastewater treatment plants in Korea

Due to the regulation on bisphenol A (BPA) in several industrialized countries, the demand for other bisphenol analogues (BPs) as substitutes for BPA is growing. Eight BPs were determined in sludge from 40 representative wastewater treatment plants (WWTPs) in Korea. Total concentrations of BPs (ΣBP) in sludge ranged from <LOQ to 25700ngg−1. The highest concentrations of ΣBP were found in sludge collected from WWTPs that received discharges from the paper and textile industries. The profiles of BPs were dependent on the proportions of industrial wastewater treated at each of the WWTPs. The sludge from industrial WWTPs contained elevated proportions of BPA, whereas sludge from domestic WWTPs was dominated by bisphenol F (BPF), suggesting use of BPF in certain industrial products in Korea. No significant correlations were found between BPs and the WWTP characteristics. The average per-capita emissions of BPs ranged from 0.04 (BPP) to 886gcapita−1d (BPA) through WWTP discharges. The emission fluxes of ΣBP through industrial WWTPs were 2–3 orders of magnitudes higher than those calculated for domestic WWTPs, indicating that industrial discharges are the major source of BPs into the Korean environment. This is the first nationwide survey of BPs in sludge from Korean WWTPs.