Biofiltration Process Research Articles

Effects of treatment processes on AOC removal and changes of bacterial diversity in a water treatment plant

The effectiveness of different treatment processes on assimilable organic carbon (AOC) removal and bacterial diversity variations was evaluated in a water treatment plant. The van der Kooij technique was applied for AOC analysis and responses of bacterial communities were characterized by the metagenomics assay. Results show that the AOC concentrations were about 93, 148, 43, 51, 37, and 38 μg acetate-C/L in effluents of raw water basin, preozonation, rapid sand filtration (RSF), ozonation, biofiltration [biological activated carbon (BAC) filtration], and chlorination (clear water), respectively. Increased AOC concentrations were observed after preozonation, ozonation, and chlorination units due to the production of biodegradable organic matters after the oxidation processes. Results indicate that the oxidation processes were the main causes of AOC formation, which resulted in significant increases in AOC concentrations (18–59% increment). The AOC removal efficiencies were 47, 28, and 60% in the RSF, biofiltration, and the whole system, respectively. RSF and biofiltration were responsible for the AOC treatment and both processes played key roles in AOC removal. Thus, both RSF and biofiltration processes would contribute to AOC treatment after oxidation. Sediments from the raw water basin and filter samples from RSF and BAC units were collected and analyzed for bacterial communities. Results from scanning electron microscope analysis indicate that bacterial colonization was observed in filter materials. This indicates that the surfaces of the filter materials were beneficial to bacterial growth and AOC removal via the adsorption and biodegradation mechanisms. Next generation sequencing analyses demonstrate that water treatment processes resulted in the changes of bacterial diversity and community profiles in filters of RSF and BAC. According to the findings of bacterial composition and interactions, the dominant bacterial phyla were Proteobacteria (41% in RSF and 56% in BAC) followed by Planctomycetes and Acidobacteria in RSF and BAC systems, which might affect the AOC biodegradation efficiency. Results would be useful in developing AOC treatment and management processes in water treatment plants.

Microbial Biomass, Composition, and Functions Are Responsible for the Differential Removal of Trace Organic Chemicals in Biofiltration Systems: A Batch Study

Biofiltration processes help to remove trace organic chemicals (TOrCs) both in wastewater and drinking water treatment systems. However, the detailed TOrCs biotransformation mechanisms as well as the underlying drivers behind the variability of site specific transformation processes remain elusive. In this study, we used laboratory batch incubations to investigate the biotransformation of 51 TOrCs in eight bioactive filter materials of different origins treating a range of waters, from wastewater effluents to drinking water. Microscopy, 16S rRNA amplicon and whole metagenome sequencing for assessing associations between the biotransformation rate constants, microbial composition and genetic potential complemented chemical analysis. We observed strong differences in the mean global removal of TOrCs between the individual sand filters (−1.4–58%), which were mirrored in overall biomass, microbial community composition, and enzyme encoding genes. From the six investigated biomass markers, ATP turned out to be a major predictor of the mean global biotransformation rate, while compound specific biotransformations were correlated with the microbial community composition. High biomass ecosystems were indicated in our systems by a dominance of Nitrospirae, but individual TOrC biotransformation showed a correlation with rare taxa (<2%) such as Hydrogenophaga, or individual functions such as the enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase encoding genes. In general, this study provides new insights into so far rarely addressed variability of TOrCs biotransformation. We propose potential novel biological indicators for the removal performance of TOrCs in biofiltration systems, highlighting the role of living biomass in predicting and normalizing the global transformation, and the role of the microbial community for the individual transformation of TOrCs in engineered and natural systems.

A new technique for reducing accumulation, transport, and toxicity of heavy metals in wheat (Triticum aestivum L.) by bio-filtration of river wastewater

The occurrence of contaminants such as heavy metals in an aqueous environment has become a global concern. In the present study, a bio-filter was designed to eliminate heavy metals from river wastewater contaminated with industrial effluents. Moreover, we analyzed simple tap water, bio-filtered water, and unfiltered river wastewater and measured the concentrations of different heavy metals in the samples, such as cadmium (Cd), nickel (Ni), lead (Pb), and copper (Cu). The current experiment explored irrigation effects of three water regimes (tap water, bio-filtered water, and wastewater) on two wheat (Triticum aestivum L.) varieties (NARC-2009 and NARC-2011). Results of the present study indicated that wastewater negatively influenced the growth parameters and photosynthetic contents along with a significant increase in oxidative damage in terms of electrolyte leakage (EL) (50 and 61%), hydrogen peroxide (H2O2) (52 and 61 μmol/g), and malondialdehyde (MDA) (16 and 17.7 μmol/g) contents in NARC-2009 and NARC-2011 respectively. However, bio-filtered water positively regulated the growth profile, activities of antioxidants such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), total soluble sugars, amino acids, total protein, and proline contents in wheat as compared with untreated wastewater. In addition, bio-filtered water had significant impacts on the reduction of Cd, Ni, Pb, and Cu concentrations in roots, shoots, and grains of both wheat varieties as compared to wastewater. The concentrations (mg/kg) of Cd (15 and 18), Ni (35 and 57), Pb (5 and 7), and Cu (69 and 72) in roots, Cd (5 and 6), Ni (24 and 43), Pb (3 and 4), and Cu (16 and 19) in shoots, and Cd (0.7 and 1.0), Ni (11 and 26), Pb (2 and 3), and Cu (1.6 and 1.5) in grains of NARC-2009 and NARC-2011 were found under river wastewater treatment. Overall, wastewater treatment through bio-filtration process is an effective strategy for the reduction of toxic elements in bio-filtered water and their accumulation by plants.

Removal of ammonia in raw water taken from Surabaya river using biofiltration process

Research on the removal of ammonia in raw water taken from the Surabaya river has been carried out. The study was conducted by operating a biofilter pilot plant consisting of lamella type-sedimentation tanks and biofilter reactors filled with honeycomb type-plastic media. The results of the study showed that the biofilter process which consists of sedimentation tanks and biofilter reactors can reduce turbidity, ammonia, and nitrite inside raw water. Generally, the longer the retention time in the biofilter pilot plant is, the greater the efficiency is in eliminating turbidity, ammonia, and nitrite in the raw water. With the total retention time of 81 minutes in the biofilter test model, the efficiency of turbidity, ammonia, nitrate, and nitrite was 33.83%, 57.84%, 16.40%, and 59.41%, respectively. Based on the results of the research above, it was found that with the ammonia load of 1 until 5 gr/m3. Hours (24 until 120 gr/m3.day), it efficiently reduced the ammonia compounds by 30%-50%. In the chlorination process, chlorine compounds can react with ammonia compounds in the raw water, so by decreasing the concentration of ammonia, the consumption of chlorine will be reduced, resulting in lower production costs. With the reduced use of chlorine compounds, the potential formation of micropollutant compounds due to the chlorination process will also be reduced.

Biological ion exchange as an alternative to biological activated carbon for natural organic matter removal: Impact of temperature and empty bed contact time (EBCT)

Biofiltration is a widely used process in drinking water treatment plants to remove natural organic matter (NOM). A novel biofiltration process using ion exchange resins as supporting media (i.e., biological ion exchange or BIEX) has been demonstrated to provide a superior performance compared to conventional biological activated carbon (BAC). In order to optimize the performance of BIEX filters, the impact of temperature and empty bed contact time (EBCT) on NOM removal was systematically studied. In the present study, bench-scale BIEX filters were set up in parallel with BAC filters and operated at different temperatures (i.e., 4 °C, 10 °C and 20 °C) and EBCTs (i.e., 7.5 min, 15 min and 30 min). Higher average dissolved organic carbon (DOC) removal was achieved in BIEX filters (73 ± 6%) than BAC filters (22 ± 9%) at the steady state with an EBCT of 30 min. Higher temperatures improved NOM removal in both BAC and BIEX filters, with the impact being greater at lower EBCTs (i.e., 7.5 min and 15 min). Higher EBCTs could also improve NOM removal, with the impact being greater at lower temperatures (i.e., 4 °C and 10 °C). DOC removal for BIEX and BAC filters can be modeled with a first-order kinetic model (R2 = 0.93–0.99). BAC had a higher temperature activity coefficient than BIEX (1.0675 vs. 1.0429), indicating that temperature has a greater impact on BAC filtration than BIEX filtration. Overall, temperature and EBCT must be considered simultaneously for biofilters to efficiently remove NOM.

Study on performance and mechanism of enhanced low-concentration ammonia nitrogen removal from low-temperature wastewater by iron-loaded biological activated carbon filter

In order to strengthen the treatment of low-concentration ammonia nitrogen wastewater at low temperature, iron-loaded activated carbon (Fe-AC) with ultrasonic impregnation method was used as the filter material of biofilter process. The performance and mechanism of ammonia nitrogen removal from simulated secondary wastewater by iron-loaded biological activated carbon filter (Fe-BACF) were studied at 10 °C. The characterization results showed that iron was loaded on the surface of AC in the form of Fe2O3, and the specific surface area, total pore volume, pore size and alkaline functional group content of Fe-AC were obviously increased. After the formation of biofilm on the surface of filter media, the average removal rate of ammonia nitrogen by Fe-BACF (97.9%) was significantly higher than that of conventional BACF (87.8%). The improved surface properties increased the number and metabolic activity of microorganisms, and promoted the secretion of EPS on the surface of Fe-BAC. The results of high-throughput sequencing showed that the existence of Fe optimized the bacterial community structure on the surface of Fe-BAC, with the increase of the abundances of psychrophilic bacteria and ammonia nitrogen removal bacteria. The mechanism of enhanced ammonia nitrogen removal by Fe-BACF was the joint action of many factors, among which the main causal relationship was that modification of iron could optimize the number and category of microorganisms on Fe-BAC surface by improving the surface properties, thus improving the biological nitrogen removal ability. Results of this study provided a practical way for the treatment of low ammonia nitrogen wastewater in cold regions.

Achieving advanced nitrogen removal in a novel partial denitrification/anammox-nitrifying (PDA-N) biofilter process treating low C/N ratio municipal wastewater

For achieving mainstream anammox, a novel partial denitrification/anammox-nitrifying (PDA-N) biofilter process to treat municipal wastewater was developed. This process achieved a total inorganic nitrogen (TIN) removal efficiency of 81%, with an average effluent TIN of 7.31 mg·L-1, when the ratio of influent chemical oxygen demand (COD) to TIN was 3.2. Approximately 97% of the TIN was removed by anammox in the PDA biofilter. Nitrite was provided by partial denitrification for anammox. Partial denitrification was driven by Thaurea in the middle and lower regions of the PDA biofilter, while anammox was mainly driven by Candidatus Brocadia in the middle and upper regions. When treating real municipal wastewater, the TIN was efficiently removed in the PDA-N biofilter, with the effluent TIN of 5.96 mg·L-1. Anammox played a primary role, achieving approximately 98% of the TIN removal. Compared to the traditional nitrification/denitrification process, this process can economize organic carbon demand and oxygen consumption.

Perencanaan Instalasi Pengolahan Limbah Cair Rumah Sakit Aliyah 3 Kota Kendari

The purpose of this study was to determine the amount of liquid waste discharge at the hospital. Data from the number of hospital patient beds is 54 beds, so the activities taking place in Aliyah Hospital 3 in Kendari city produces a maximum discharge of liquid waste of 3.78/day. The form and design of processing liquid waste which is a rectangle with anaerobic- aerobic bio filter treatment system. Liquid waste processing with anaerobic-aerobic bio filter process consists of several parts namely the oil separator tank, equalization tank, early settling tank, anaerobic bio filter tank, aerobic bio filter tank, final settling tank and equipped with a chlorinated contractor tub. As for the size of each tank, which is like an oil separator tank (0,9 m × 0,5 m × 0,7 m), equalization tank (2,6 m × 1,3 m × 1,1 m), early settling tank (1,6 m × 0,8 m × 0,9 m), anaerobic bio filter tank (2,5 m × 1,3 m × 1,4 m), aerobic bio filter tank (1,8 m × 1 m × 1 m), final settling tank (1,8 m × 0,7 m × 0,7 m) and chlorinated tank (0,6 m × 0,3 m × 0,4 m). This process system was chosen because it is in accordance with the amount of liquid waste treatment system is safe, inexpensive and easy to operate.

Perencanaan Instalasi Pengolahan Limbah Cair Rumah Sakit Aliyah 3 Kota Kendari

The purpose of this study was to determine the amount of liquid waste discharge at the hospital. Data from the number of hospital patient beds is 54 beds, so the activities taking place in Aliyah Hospital 3 in Kendari city produces a maximum discharge of liquid waste of 3.78/day. The form and design of processing liquid waste which is a rectangle with anaerobic- aerobic bio filter treatment system. Liquid waste processing with anaerobic-aerobic bio filter process consists of several parts namely the oil separator tank, equalization tank, early settling tank, anaerobic bio filter tank, aerobic bio filter tank, final settling tank and equipped with a chlorinated contractor tub. As for the size of each tank, which is like an oil separator tank (0,9 m × 0,5 m × 0,7 m), equalization tank (2,6 m × 1,3 m × 1,1 m), early settling tank (1,6 m × 0,8 m × 0,9 m), anaerobic bio filter tank (2,5 m × 1,3 m × 1,4 m), aerobic bio filter tank (1,8 m × 1 m × 1 m), final settling tank (1,8 m × 0,7 m × 0,7 m) and chlorinated tank (0,6 m × 0,3 m × 0,4 m). This process system was chosen because it is in accordance with the amount of liquid waste treatment system is safe, inexpensive and easy to operate.

개인하수처리시설의 배출특성 및 관리방안 연구

Individual sewage treatment process (ISTP) is classified into a sewage treatment system which treats all the domestic sewage and a water-purifier tank which treats only effluent flushing from the toilet. The granular sludge-sequencing batch reactor (GS-SBR) represent an attractive alternative to the ISTP due to their small footprint and their low energy consumption and excess sludge production. The objectives of this study is to analyze an operating factors of the ISTP for enhancing nitrogen removal and to figure out the performance of anaerobic/oxic GS-SBR as an alternative of ISTP (activated sludge process, contact oxidation process, biofiltration process). As a result, the efficiencies of the real ISTP showed a very fluctuating effluent qualities (BOD 0.5-47.6 mg/L, COD 1.4-71.1 mg/L, T-N 1.1-114.7 mg/L, T-P 0.073-15.041 mg/L). This indicates an alternative of cost-effectiveness process is needed to enhancing nitrogen removal rate despite a fluctuating influent concentration. As an alternative to the ISTP, the GS-SBR performance achieved high nitrogen efficiencies of <79.8 % at influent carbon/nitrogen (C/N) ration of 1-3, the food/microorganism (F/M) ratios of 0.25kgCOD /kgMLVSS/d, and the operation mode of aeration/non-aeration (1.5:1-3:1). This result indicates the anaerobic/oxic GS-SBR could be used as an alternative of the ISTP to improve the river water quality.

Application of an indigenous microorganisms-based fixed-bed GAC-biofilm reactor for passive and sustainable treatment of oil sands process water through combined adsorption and biodegradation processes

In this study, a fixed-bed biofilm reactor (biofilter) was developed and applied for oil sands process water (OSPW) remediation by using granular activated carbon (GAC) as packing media. Using quantitative polymerase chain reaction (qPCR) detection, the total bacterial copy number (16S) in the GAC biofiltration system was found to reach a relatively stable level (1.3 ± 0.2 × 109 copies/g GAC) after 62 days of operation, and the thickness of biofilm on GAC surface was 26.7 ± 4.3 μm based on the scan of confocal laser scanning microscopy (CLSM). The established GAC-biofilter showed 95.4% naphthenic acids (NAs) removal from raw OSPW after 2 months of operation. The GAC-biofilter also showed 88.3% NAs removal after a long operation time (2 years), indicating its sustainable bioremediation capacity for OSPW. 16S and 18S rRNA gene-targeted metagenomic sequencing showed that the microbial community in the GAC biofilter had higher diversity and richness than that found in the sand biofilter which was used for OSPW treatment previously. Comamonadaceae and Saccharomycotina were found to be the dominant bacterial and fungal families in the GAC biofilter, respectively. Xenobiotic metabolism function of the microbial community may contribute significantly to the biodegradation of NAs. The GAC biofiltration process is a promising passive OSPW treatment approach that can be used in-situ.

Removal of antibiotics in sand, GAC, GAC sandwich and anthracite/sand biofiltration systems

Drinking water biofiltration offers the possibility of the removal of trace level micropollutants from source water. Sand, granular activated carbon (GAC), GAC sandwich (a layer of GAC loaded in the middle of sand bed), and anthracite-sand dual biofilters were set-up in duplicate at bench-scale to mimic the filtration process in real drinking water treatment works. During the 3-month system operation, removal of five antibiotics (amoxicillin, clarithromycin, oxytetracycline, sulfamethoxazole, and trimethoprim) and overall biofilter performance were evaluated. Natural surface water spiked with a mixture of the target antibiotics was used as feedwater to the biofilters. Results showed that the target antibiotics were substantially removed (>90%) by GAC-associated biofilters and partially removed (≤20%) by sand alone and anthracite-sand biofilters. In particular, the GAC sandwich biofilter exhibited superior performance compared to sand/anthracite biofilter, and the comparisons among all biofilters indicated that both adsorption and biodegradation contributed to the removal of the target antibiotics in the GAC-associated biofilters. Adsorption kinetics showed that sulfamethoxazole fitted with pseudo-first-order adsorption model, while trimethoprim, amoxicillin, oxytetracycline and clarithromycin fitted the pseudo-second-order model. All antibiotics fitted the Langmuir model according to the isotherm experiment. To date, this is the first study evaluating the removal of antibiotics by GAC sandwich biofilters. Overall, this research will provide useful information which can be used for optimising or updating existing biofiltration processes in industry to reduce antibiotic residues from source water.

Succession of the microbial community during the process of mechanical and biological pretreatment coupled with a bio-filter for removal of VOCs derived from domestic waste: a field study.

Changes in the microbial community can not only reflect the efficiency of waste disposal, but also reveal the effect of odor control during the treatment process. This study aimed to evaluate the removal efficiency of volatile organic compounds (VOCs) by the process of mechanical and biological pretreatment (MBP) coupled with a bio-filter (BF). An interesting phenomenon was found that the VOCs were effectively reduced through the MBP process. To understand the removal mechanism of VOCs, the abundance and diversity of microbial bacteria and fungi in the biological dehydration (BD) process, biological fermentation process, and BF process were explored. The abundance and diversity of microbes in the BF were relatively high, of which the bacteria such as Lactobacillus, Bacillus and Candida were the dominant species for VOCs treatment. The proposed technical process and the positive effects observed in this study indicate that it could be applied to the control of VOCs in the treatment of domestic waste.

Green Climate Control

Several studies have demonstrated the potential of botanical biofiltration and phytoremediation to remove indoor pollutants and improve overall comfort. However, there is a lack of evidence on how indoor greenery affects the Indoor Environmental Quality (IEQ), particularly on Indoor Air Quality (IAQ). The main goal of this research project was to explore and evaluate the efficacy of an active plant-based system in terms of IAQ and being able to answer the main research question: “Can an active plant-based system improve the Indoor Air Quality (IAQ)?” This was achieved through laboratory studies of several plant-based systems, including chemical, physical and sensorial evaluations as well as qualitative and quantitative assessments. Some of the outcomes of this research are described below: – To develop an effective plant-based system the proper selection of its components is essential. – In real settings, the concentration of the gaseous pollutants is present in lower levels and current equipment are not able to detect them. Therefore, it is clear and confirmed that physical, chemical and sensory assessments are crucial to evaluate the real impact of plant‑based system in the IAQ. – In this project, different substrates and plants were tested and it became clear that the substrate is an important ally in reducing gaseous pollutants, such as formaldehyde. – The polluted air needs to be transported to the vicinity of the plant-based system to be able to uptake the gaseous pollutant. Therefore, an active plant-based system is needed to potentialize the impact of such systems in the IAQ since the air has to be forced to go through the system to achieve the biofiltration process. – An indoor forest is required to meet the minimum standards for ventilation rates in breathing zones just with plants without any extra mechanical ventilation.

Simultaneous removal of ammonia and volatile organic compounds from composting of dead pigs and manure using pilot-scale biofilter

ABSTRACT Odor emission is one of the most common problems associated with dead animals composting. Biofiltration treatment for eliminating exhaust odors formed during dead pigs and manure composting has been studied. The composting and biofiltration process consisted of two series of tests. Composting experimental trials lasted 6 weeks, and composting was performed using six pilot-scale reactor vessels. A total of 37 kinds of volatile organic compounds (VOCs) present in the air were identified, and temporal variations were determined during the 42 days of composting. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component according to odor active values (OAVs). Nine biofilter vessels containing mature compost were used in studying the effect of different (30, 60, and 100 s) empty bed retention times (EBRT) on the simultaneous removal efficiencies (REs) of NH3, DMS, DMDS, DMTS, and TMA. Results indicated that the inlet concentration of NH3 applied was 12–447 mg m−3, and the average removal efficiencies were 85.4%, 88.7%, and 89.0% for EBRTs of 30, 60, and 100 s, respectively. The average REs of DMS, DMDS, DMTS, and TMA were 79.2%–95.4%, 81.9%–94.0%, 76.7%–99.1%, and 92.9%–100%, respectively, and their maximum elimination capacity (ECs) were 220, 1301, 296, and 603 mg m−3 h−1, respectively. The optimal EBRT for the stimulation removal of NH3, DMS, DMDS, DMTS, and TMA was 60 s. Implications: Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component during dead pigs and manure composting. Biofilter with mature as media can be used to stimulation remove NH3, DMS, DMDS, DMTS, and TMA, the optimal empty bed retention times EBRT was 60 s.

Volatile organic compounds, ammonia and hydrogen sulphide removal using a two-stage membrane biofiltration process

The analysis of biofiltration efficiency was performed with parallel VOC, H2S and NH3 removal using pilot two-stage biofilters including conventional biofiltration and purification on a membrane filter. The scope of the research was to determine the relationship between the technological parameters of the tested device (two beds and two membranes) and gases removal efficiency. Research was carried out in a semi-technical scale in three industrial plants: mechanical-biological municipal waste treatment (MBT), food industry (FI) and wastewater treatment (WWTP) plants. Experimental results indicate the efficiency removal of VOCs from 89% (WWTP) to 98% (FI), NH3 from 88% (WWTP) to 100% (MBT) and H2S from 93% (WWTP) to 100% (MBT). Biofilter with stumpwood chips-bark-compost bed, fortified with the more porous membrane was the most effective, allowing VOC, NH3 and H2S removal with an average efficiency of 99% for NH3 and H2S and 97% for VOCs. The application of membrane fabrics as the second stage of purification allows high efficiency simultaneous removal of VOCs, NH3 and H2S. Unlike two-stage purification, conventional biofiltration is effective at removing individual impurities from process gases. The results of this study indicate a high potential for practical application.

Biological Waste Air and Waste Gas Treatment: Overview, Challenges, Operational Efficiency, and Current Trends

International contracts to restrict emissions of climate-relevant gases, and thus global warming, also require a critical reconsideration of technologies for treating municipal, commercial, industrial, and agricultural waste gas emissions. A change from energy- and resource-intensive technologies, such as thermal post-combustion and adsorption, as well to low-emission technologies with high energy and resource efficiency, becomes mandatory. Biological processes already meet these requirements, but show restrictions in case of treatment of complex volatile organic compound (VOC) mixtures and space demand. Innovative approaches combining advanced oxidation and biofiltration processes seem to be a solution. In this review, biological processes, both as stand-alone technology and in combination with advanced oxidation processes, were critically evaluated in regard to technical, economical, and climate policy aspects, as well as present limitations and corresponding solutions to overcome these restrictions.

The hybrid system successfully to consisting of activated sludge and biofilter process from hospital wastewater: Ecotoxicological study

This article aimed to demonstrate solution hospital wastewater due to more consumption of antibiotics, public concern has been significantly increased for usage, fates and occurrences of these emerging compounds in the environments and biota. Therefore, it does need more discoveries about occurrences and new treatment methods. Since the conventional treatment methods are low efficient on antibiotics, integration and combination of biological systems together or with an additional process has been shown that provided a better result. However, here, the potential of a full scale combined treating system with activated sludge-scoria biofilter (ASSB) was investigated for removal of ceftriaxone (CEF) and amoxicillin (AMX). To determine the potential biodegradability of proposed system, the solid-water distribution coefficient (Kd) was calculated. Overally, 118 samples were collected from three points; wastewater entering, exiting the activated sludge, and exiting the biofilter. To determine the amount of CEF and AMX antibiotics, the samples were analyzed using HPLC-UV. The results showed that the activated sludge system were able to eliminate the AMX and CEF antibiotics about 70.36 and 84.49%, respectively. In compare to activated sludge, the average mean of ASSB system for the removal efficiency were 87.53% (for AMX) and 93.17% (for CEF), respectively. As a result, it can be found that the efficiency of the combined activated sludge-biofilter system in removing of the low levels of antibiotics was more than individual activated system. The result of Kd revealed that AMX (with a Kd about 0.172) has lower tendency to biomass rather than CEF (with a Kd about 0.512). The ecological toxicity assessment guaranteed there is no risk for fish and daphnia when the activated sludge and also ASSB effluents to be discharged into the environment even without any diluting.

Performance of coupling electrocoagulation and biofiltration processes for the treatment of leachate from the largest landfill in Hanoi, Vietnam: Impact of operating conditions

Landfill leachate remediation is quite challenging because of the presence of various different organic, inorganic compounds, microorganism materials, and heavy metals. Especially in case of a mature leachate, if only a single biological treatment system is applied, it will not be effective due to the high percentage of heat-resistant compounds, including mostly humic substances. Therefore, combining processes are necessary to effectively remove these substances to enhance the effectiveness of leachate remediation and to meet the water qualitystandards. In this research, a hybrid electrocoagulation-biofiltration system was applied to investigate the treatment of Nam Son landfill leachate, the largest landfill in the North of Vietnam. The results revealed the electrocoagulation (EC) process using iron anode could eliminate about 70% COD and 90% nitrate when applying the optimal conditions: current density of 3 A/m2, at initial pH = 8, with a treatment time of 60 min, and an inter-electrode distance of 7 cm. The subsequent biofiltration (BF) process was capable of removing almost completely ammonia and remained COD from EC-pretreated leachate. The optimal parameters of aeration/pause mode and loading rate determined for BF process were 60:60 min and 5 L/d, respectively. These results demonstrated that an EC-BF hybrid process can be considered a model process for the removal of both organic and inorganic pollutants from landfill leachate.

하수처리 방류수 처리 시 파일럿 규모 생물막 공법의 수리학적 체류시간 및 반송비의 영향

하수처리 방류수 처리 시 파일럿 규모 생물막 공법의 수리학적 체류시간 및 반송비의 영향