scholarly journals Removal of Organic Micropollutants in Wastewater Treated by Activated Sludge and Constructed Wetlands: A Comparative Study

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2515 ◽  
Author(s):  
Carolina Reyes Contreras ◽  
Daniela López ◽  
Ana M. Leiva ◽  
Carmen Domínguez ◽  
Josep M. Bayona ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Constructed Wetlands ◽  
Rural Community ◽  
Treatment Plant ◽  
Transformation Products ◽  
Organic Micropollutants ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Significant Difference ◽  
Removal Efficiencies

The aim of this study is to compare the removal of organic micropollutants (OMPs) in wastewater by activated sludge (AS) and constructed wetlands (CWs). This analysis was carried out in a wastewater treatment plant (WWTP) of a rural community where they implemented two technologies in parallel: AS and a pilot plant of horizontal subsurface flow (HSSF) constructed wetlands. In this case, these systems were fed by the same influent and the removal efficiencies of 14 OMPs, including analgesics/anti-inflammatories, anticonvulsants, stimulants, antifungals, fragrances, plasticizers, and transformation products, were evaluated in each system. Regarding the presence of OMPs in the wastewater, the concentrations of these compounds in the influent ranged from 0.16 to 7.75 µg/L. In general, the removal efficiencies achieved by the AS system were between 10%–95% higher than those values reported by HSSFs with values above 80% for naproxen, ibuprofen, diclofenac, caffeine, triclosan, methyl dihydrojasmonate, bisphenol-A, 2-hydroxyl ibuprofen, and carboxy ibuprofen (p < 0.05). This behavior can be related to the aerobic conditions that promote the AS system with oxidation-reduction potential (ORP) and dissolved oxygen (DO) values above −281 mV and 0.24 mg/L, respectively. However, the removal of galaxolide was greater in HSSF system than in AS with significant difference of 70% (p < 0.05). Despite these results, this study reveals that comparing both technologies, AS had the best removal performance of these OMPs studied.

Improving the sensitivity of the activated sludge respiration inhibition test and verifying the results using an oxidation-reduction potential electrode

2016 ◽  
Vol 75 (2) ◽  
pp. 247-254 ◽  
Author(s):  
F. Friedrichs ◽  
K. U. Rudolph ◽  
Bich Hanh Nguyen ◽  
D. Meinardi ◽  
W. Genthe ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Oxygen Sensor ◽  
Reduction Potential ◽  
Treatment Plant ◽  
Inhibition Test ◽  
Synthetic Wastewater ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Potential Electrode ◽  
Nutrient Solutions

The inhibition of activated sludge respiration is one of the most important parameters for monitoring wastewater toxicity. The main objective of this study was to improve respiration inhibition testing in order to protect the biological degradation within the aerobic process in a wastewater treatment plant more efficiently. In order to influence the sensitivity of the testing bacteria, two different nutrient solutions were selected for biological testing, synthetic wastewater according to ISO 8192 and NaAc (sodium acetate). The effects of the nutrient solutions on heavy metal speciation and their respiration inhibition were investigated. The toxicants Zn(II), Cu(II), Cr(VI) and 3,5 DCP (3,5-dichlorophenol) were used as standards to determine toxicities and to study the influence of nutrient solutions. Results have shown that NaAc as a nutrient solution sensitized the respiration inhibition test up to a factor of 7.7. Furthermore, an oxidation reduction potential electrode can be used as an alternative tool to verify the results obtained with an oxygen sensor.

Automatic Regulation of Activated Sludge Aeration – Single-Tank Nitrification-Denitrification

1993 ◽  
Vol 28 (10) ◽  
pp. 289-298 ◽  
Author(s):  
F. Lefevre ◽  
J. M. Audic ◽  
B. Bujon
Keyword(s):  
Activated Sludge ◽  
Nitrogen Concentration ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Automatic Regulation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
User Friendly ◽  
Activated Sludge Processes

Several activated sludge processes using intermittent aeration were developed during the last decade to improve nitrogen removal. Timers, oxidation-reduction or oxygen probes are often used to switch aeration on and off at preset times or by upper and lower limits. These regulation systems cannot adjust the oxygen supply to the biological oxygen demand and cannot realize the supply when “requested” by the influent. A new controller/regulator system (OGAR: Optimized manaGement of Aeration by Redox) based on the variation with time of the oxidation reduction potential was developed : EH = f(time). This OGAR system controls the aeration periods and therefore optimizes the nitrification and denitrification reactions in the sludge processes. The operation of the OGAR programmable controller can be summarized by three functions: It is a true diagnostic tool and a decision making aid. Its simple design enables it to be adapted easily to any site and to be highly user-friendly. OGAR was applied to an existing wastewater treatment plant located at Nezel-la-Falaise near Paris (west suburb). Overall performance of the plant before and after implementation of automatic aeration control by OGAR yields the following conclusions:removal of COD was improved by 45 % reduction in COD from 100 mg/l to 55 mg/lammonia nitrogen concentration was reduced from 42 mg.l-1 to 2mg.1-1 and nitrate nitrogen concentration was reduced to less than 5 mg.1-1

Comparison of two treatments for the removal of selected organic micropollutants and bulk organic matter: conventional activated sludge followed by ultrafiltration versus membrane bioreactor

2011 ◽  
Vol 63 (4) ◽  
pp. 733-740 ◽  
Author(s):  
E. Sahar ◽  
M. Ernst ◽  
M. Godehardt ◽  
A. Hein ◽  
J. Herr ◽  
...  
Keyword(s):  
Organic Matter ◽  
Activated Sludge ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Macrolide Antibiotics ◽  
Organic Micropollutants ◽  
Removal Rates ◽  
Conventional Activated Sludge

The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8–10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin – at an MLSS of 6–9 g/L – showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.

Mesophilic and Thermophilic Digestion of Thickened Waste Activated Sludge: A Comparative Study

2010 ◽  
Vol 113-116 ◽  
pp. 450-458 ◽  
Author(s):  
Yong Zhi Chi ◽  
Yu You Li ◽  
Min Ji ◽  
Hong Qiang ◽  
Heng Wei Deng ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Methane Content ◽  
Waste Activated Sludge ◽  
Digested Sludge ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Significant Difference

This paper presents an experimental study over 204 days on anaerobic degradation of thickened waste activated sludge (TWAS) from a municipal wastewater treatment plant (WWTP). The experiments were conducted under thermophilic (55°C) and mesophilic (35°C) condition, respectively, by using the semi-continuous flow completely mixed reactors. The influent total solids (TS), hydraulic retention time (HRT) and chemical oxygen demand (COD) loading levels were around 4%, 30 days and 1.67 kg-CODCr•m-3•d-1 , respectively. During the opration period, the thermophilic anaerobic digestion process (TADP) and the mesophilic anaerobic digestion process (MADP) were stable and well-functioned without ammonia inhibition. Particulate organic matters reduction of TADP was superior to that of MADP. This result implies that TADP has higher sludge reduction efficiency than MADP. According to the simulated chemical formula of TWAS, C5.85H9.75O3.96N, and the stoichiometric equation, the methane content and the ammonia yield in the anaerobic process could be calculated, which were consistent with the experimental results. The methane yield of TADP was a little higher than that of MADP. The statistical mean values of methane content for TADP and MADP were 60.97% and 62.38%, respectively.According to paired t-test, there was a significant difference in methane content between TADP and MADP(α=0.01, n=62). Compared with the mesophilic digested sludge, the dewaterability of thermophilic digested sludge was lower.

scholarly journals Dynamic control of nutrient-removal from industrial wastewater in a sequencing batch reactor, using common and low-cost online sensors

2015 ◽  
Vol 73 (4) ◽  
pp. 740-745 ◽  
Author(s):  
Jan Dries
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Industrial Wastewater ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Low Cost ◽  
Dynamic Control ◽  
Oxygen Demand ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

On-line control of the biological treatment process is an innovative tool to cope with variable concentrations of chemical oxygen demand and nutrients in industrial wastewater. In the present study we implemented a simple dynamic control strategy for nutrient-removal in a sequencing batch reactor (SBR) treating variable tank truck cleaning wastewater. The control system was based on derived signals from two low-cost and robust sensors that are very common in activated sludge plants, i.e. oxidation reduction potential (ORP) and dissolved oxygen. The amount of wastewater fed during anoxic filling phases, and the number of filling phases in the SBR cycle, were determined by the appearance of the ‘nitrate knee’ in the profile of the ORP. The phase length of the subsequent aerobic phases was controlled by the oxygen uptake rate measured online in the reactor. As a result, the sludge loading rate (F/M ratio), the volume exchange rate and the SBR cycle length adapted dynamically to the activity of the activated sludge and the actual characteristics of the wastewater, without affecting the final effluent quality.

Removal of organics from wastewater using a novel biological hybrid system

2001 ◽  
Vol 43 (1) ◽  
pp. 321-326 ◽  
Author(s):  
H. A. Al-Sharekh ◽  
M. F. Hamoda
Keyword(s):  
Activated Sludge ◽  
Hybrid System ◽  
Treatment Plant ◽  
Minor Effect ◽  
Loading Rates ◽  
Innovative System ◽  
The Mean ◽  
Percentage Removal ◽  
Removal Efficiencies ◽  
A Minor

This paper summarizes the results obtained using the hybrid aerated submerged fixed-film (HASFF) process. HASFF is an innovative system comprising a four-compartment reactor having an array of fixed ceramic plates maintained under diffused aeration to support attached biomass, with activated sludge recycle to promote suspended growth in the reactor. Wastewater from a municipal treatment plant was fed to the reactor and its activated sludge was used for recycling in the hybrid system. Four pilot units were operated in the plant at various hydraulic retention times, HRTs (2, 4, 6 and 8 h), using primary-settled wastewater under organic loading rates up to 0.7 g BOD/gMLTVS · d. Data obtained showed that the overall BOD percentage removal efficiencies were consistently above 94.0% at all HRTs including the 2 hours while the COD percentage removal efficiencies ranged between 65.7–76%. The effluent's mean filtered BOD concentration ranged between 4.5–7.5 mg/l whereas the mean filtered COD concentration ranged between 70.0–89.6 mg/l. Increasing the hydraulic loading rate by four-folds from 0.08 to 0.32 m3/m2 · d had a minor effect on the unit's BOD and COD percentage removal efficiencies indicating a robust biological process that is resilient to hydraulic shock loads, thereby offering a viable upgrading option.

Simultaneous activated sludge wastewater treatment and odour control

2001 ◽  
Vol 44 (9) ◽  
pp. 189-196 ◽  
Author(s):  
P. Hardy ◽  
J.E. Burgess ◽  
S. Morton ◽  
R.M. Stuetz
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Treatment Process ◽  
Treatment Plant ◽  
Process Performance ◽  
Wastewater Treatment Process ◽  
Wet Scrubbing ◽  
Odour Control ◽  
Removal Efficiencies ◽  
Performance Results

Lab-scale tests were used to determine the amount of H2S that can be treated using a range of different activated sludges. Static vessels were used to study the effects of different H2S concentrations (5, 25, 50 and 75 ppm). The data indicated that odour control may be carried out using certain types of sludge, but sludge type, e.g. carbonaceous, nitrifying, with or without coagulant, affects removal efficiency. The presence of the biomass resulted in greater H2S removal than the use of wet scrubbing and the adverse effects on mixed liquor were negligible. A pilot plant was used to study the removal efficiencies of activated sludge diffusion using a typical wastewater treatment plant H2S concentration and investigated the effects that the diffusion of H2S had on the process performance. Results indicated that the levels of H2S produced by other unit processes on a wastewater treatment site (approximately 5 ppm) can be treated using activated sludge diffusion without compromising the performance of the wastewater treatment process. The only effects on the activated sludge plant observed were: (1) nitrification was interrupted briefly as H2S diffusion commenced and (2) the species' diversity in the sludge decreased.

scholarly journals Coke oven wastewater treatment by two activated sludge systems

2013 ◽  
Vol 8 (1) ◽  
pp. 16-22
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Coke Oven ◽  
Synthetic Wastewater ◽  
Removal Efficiencies ◽  
Activated Sludge Systems

In this study two bench scale activated sludge systems were used, a CSTR and an SBR for the treatment of coke – oven wastewater. Both reactors were inoculated with activated sludge from a municipal wastewater treatment plant. At the first stages of operation, reactors were feed by a mixture of municipal wastewater and synthetic wastewater. Full acclimatization of the microorganisms to synthetic wastewater was achieved in 60 days. The operation of the reactors was divided into three distinct periods. The first period was characterized by the treatment of high organic but non-toxic synthetic wastewater. During this period COD and BOD5 removal efficiencies reached 95 and 98% respectively, in both reactors. Nutrient removal was better in the SBR reactor rather than in the CSTR. In the second period phenol was added in concentrations up to 300 mg l-1. Degradation of phenol started about the 20th day after its introduction to the reactors. In this period no effects of phenol to nutrient removal were observed, whereas the removal efficiency of organic matter in both reactors was slightly decreased. During the third period phenol concentrations of the influent were gradually increased to 1000 mg l-1, while cyanide and thiocyanite were added to the influent composition to concentrations reaching concentrations of 20 and 250 mg l-1 respectively. The composition of the influent of this period was a full assimilation of coke oven wastewater. Introduction of increased phenol concentrations along with cyanide compounds initiated irreversible effects on the activated sludge microfauna of the CSTR causing inherent problems to the treatment process, while SBR showed greater capacity to withstand and degrade toxic compounds. The beginning of this period was characterized by decreased settleability of the suspended solids as well as decrease of organic matter and nutrient removal efficiencies. Monitoring of the effluent characteristics during this period reported over 90% for organic load, 85% of nutrient removal and over 90% of phenol and cyanide removal in SBR, while the removal efficiencies for the CSTR were 75, 65 and 80% respectively.

scholarly journals The effect of saw dust in a flocculent with bentonite clay and FeSO4 in AMD treatment without addition of a neutralizer

2019 ◽  
Vol 14 (3) ◽  
pp. 633-644 ◽  
Author(s):  
I. O. Ntwampe
Keyword(s):  
Reduction Potential ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Similar Treatment ◽  
Saw Dust ◽  
Jar Test ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Efficiencies ◽  
Synthetic Acid

Abstract 200 mL of synthetic acid mine drainage (AMD) was poured into five 500 mL glass beakers and treated in a jar test. The samples were dosed with 1.0–2.5 g bentonite clay, 20–60 mL of 0.025 or 0.05 M FeSO4 and 1.0–2.5 g saw dust respectively. The samples were mixed at 250 rpm for 2 minutes and reduced to 100 rpm for 10 minutes. The samples were allowed to settle for 1 hour, after which the pH, oxidation-reduction potential (ORP) and turbidity were measured (exp. A). Two other similar sets of experiments were conducted by dosing the samples with a combination of bentonite clay and FeSO4 with and without saw dust, similar treatment and measurements (exp. B and exp. C), similar treatment and measurements were conducted. The pH and the efficiencies of the flocculants containing 0.025 and 0.05 M Fe3+ in FeSO4 are similarly identical. The removal of turbid materials from the samples with FeSO4 is the lowest, followed by a combination of bentonite clay and FeSO4, whereas a combination of bentonite clay, FeSO4 and saw dust the highest. Comparative removal efficiencies between the two flocculants show that the presence of FeSO4 is relatively insignificant. The removal efficiency of a combination of bentonite clay, FeSO4 and saw dust from AMD sample is low with for Cu2+, and optimal for both Ni2+ and Fe2+ ions.

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