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1

The Treatment of Hospital Wastewater Using Electrocoagulation Process – Analysis by Response Surface Methodology

Salah Al-Shati Ahmed, Alabboodi Khalid O., Shamkhi Hassan A., Abd Zahraa N., Emeen Sara I. Mohammed

Journal of Ecological Engineering

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2023

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Vol. 24, nr 1

260--276

EN

Electrocoagulation (EC) can be defined a method utilized to remove pollutants from wastewater by applying an electric current to sacrificial electrodes. Many experimental variables like NaCl content (0–4 g/l), current density (5–25 mA/cm2), time (30–90 mins), and pH (4–10) that influence the removal efficiency regarding COD were considered. In the presented research, three distinct configurations related to electrodes, i.e. Al-Al, Fe-Al, and Fe-Fe, have been utilized to determine which was the most effective. RSM depending on BBD was utilized for optimizing various operational parameters with regard to HWW by use of EC. Maximum COD removal (97.9%) was reached at Fe-Al electrodes, NaCl (3.2 g/l), current density (24.7 mA/cm2), time (81.7 mins), and pH (7.4). COD removal (91.3%) was achieved at the Al-Al electrodes, NaCl (3.8 g/l), current density(23.5 mA/cm2), time-86.3 min, and Ph (7.7). At the Fe-Fe electrodes, the removal of COD (89.5%) was obtained at NaCl (2.3 g/l), current density (24.6 mA/cm2), pH 8.5, and time (86.9 min). This indicates that EC could remove pollutants from different types of wastewaters under many operating parameters and with arrangements of electrodes.

2

An Application of Anaerobic-Aerobic Combined Bioreactor Efficiency in COD Removal

Kavousi Rezvan, Borghei Seyyed Mehdi

Geomatics and Environmental Engineering

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2023

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Vol. 17, no. 4

5--18

EN

Over the past few decades, anaerobic-aerobic wastewater treatment systems have been widely used in industrial and municipal wastewater treatment. This study was conducted to examine the effects of combined anaerobic-aerobic bioreactors in the removal of chemical oxygen demands (COD) while reducing phosphate concentrations in synthetic wastewater. In this project, a bioreactor with the dimensions of 10 cm × 10 cm × 80 cm with respective Kaldnes packing ratios of 90 and 30% for the anaerobic and aerobic sections was designed. A combined anaerobic-aerobic reactor’s structure made changing hydraulic retention times only possible by adjusting the volume of its aerobic and anaerobic sections. In the first case, the anaerobic and aerobic sections of the reactor occupied 30 and 50 cm of its height, respectively. The height of the anaerobic section decreases to 12.5 cm in the second case. In aerobic and anaerobic sections, pH was within a neutral range, temperature was 37°C. MLSS (mixed liquor suspended solids) was 1220 and 1030 mg/L, and attached growth was 743 and 1190 mg/L respectively. In order to evaluate COD in the wastewater, three different initial phosphorus concentrations were tested: 12.8, 32.0 and 44.8 mg/L, as well as four COD: 500, 1000, 1200 and 1400 mg/L. Considering the results, COD removal is greater than 80% when the valve 2 is in the anaerobic section outlet regardless of the concentration of phosphate. In this case, the best result is for inlet COD of 500, where the reactor can eliminate more than 90%. When the COD concentration reaches 1000 to 1400 ppm, the reactor’s COD removal efficiency declines to 60%.

3

Treatment of Petroleum Refinery Wastewater by Graphite–Graphite Electro Fenton System Using Batch Recirculation Electrochemical Reactor

Kassob Ali Nadhum, Abbar Ali Hussein

Journal of Ecological Engineering

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2022

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Vol. 23, nr 10

291--303

EN

Water pollution and the lack of access to clean water are general global problems that result from the expansion of industrial and agricultural activities. Petroleum refinery wastewaters are considered as a major challenge to the environment and their treatment is mandatory. The present work investigated the removal of chemical oxygen demand (COD) from petroleum refinery effluents generated from the Al-Dewaniya petroleum refinery plant located in Iraq by utilizing a novel graphite–graphite electro-Fenton (EF) system. The electrochemical reactor was a tubular type with a cylindrical cathode made from porous graphite and concentric porous graphite rode acts as an anode. By adopting the response surface methodology (RSM), the impacts of different operating variables on the COD removal were investigated. The optimal conditions were a current density of 25 mA/cm2, FeSO4 concentration of 1.4 mM, and electrolysis time of 90 minutes, which resulted in the COD removal efficiency (RE%) of 99% at a specific energy consumption (SEC) of 10.34 kWh/kg COD. The results indicated that both current density and concentration of FeSO4 have a major impact on the elimination of COD, while time has a minor effect. The adequacy of the model equation was demonstrated by its high R2 value (0.987). The present work demonstrated that the graphite–graphite EF system could be considered as an effective approach for removing of COD from petroleum refinery wastewaters.

4

Transformation Analysis of Carbon and Nitrogen Compounds in Wastewater Treated in a Vertical Biofilter

Wawrentowicz Dariusz

Journal of Ecological Engineering

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2021

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Vol. 22, nr 11

215--222

EN

Biofilter technology for wastewater treatment is relatively complex and is gaining more interest. However, it should be emphasised that various aerobic conditions may occur in biological filter beds, which depend primarily on the velocity of wastewater flow through the bed. Therefore, it is often difficult to precisely determine the transformations of carbon and nitrogen compounds that occur during wastewater treatment on these types of filter beds. This study investigated the effectiveness of the filter bed and analysed the extent of the transformation of carbon and nitrogen compounds in the range of filtration velocities from 0.02 to 0.60 m•h-1. The study was conducted under laboratory conditions, and model wastewater was prepared on the basis of sodium acetate, ammonium chloride, potassium nitrate and potassium dihydrogen phosphate. The model wastewater was prepared with parameters corresponding to those of the treated wastewater. The experiment showed that anaerobic and aerobic conditions occurred in the biological filter bed at filtration velocities of up to 0.16 m•h-1. Above this velocity, aerobic conditions prevailed in the biological filter bed.

5

Phytoremediation Efficiency of Water Hyacinth for Batik Textile Effluent Treatment

Safauldeen Suhair Hussein, Abu Hasan Hassimi, Abdullah Siti Rozaimah Sheikh

Journal of Ecological Engineering

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2019

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Vol. 20, nr 9

177--187

EN

The present study focused on the phytoremediation efficiency of water hyacinth for the batik effluent treatment. Three operating factors were investigated such as retention times (0 to 28 days), batik effluent strength (20, 30 and 60%), and number of water hyacinth clumps (8, 10 and 12 clumps). The water hyacinth efficiencies was monitored through the measurement of dry weight, color, chemical oxygen demand (COD), total suspended solid (TSS), and pH. The highest efficiency of color and COD in the batik effluent treatment were achieved at day 7 with 83% (61 mg/L) and 89% (147 ADMI) removals, respectively. Both wastewater parameters were removed to below the Standard A for COD and Standard B for color. Meanwhile for TSS, the removal decreased as the batik effluent strength increased, where the highest removal (92%) was achieved at day 28 with 8 number of plant clumps. The pH was observed in range of 6 to 7. The results indicated that water hyacinth would be the best option for the low cost batik effluent treatment.

6

Advanced Treatment of Pre-treated Commercial Laundry Wastewater by Adsorption Process: Experimental Design and Cost Evaluation

Veli Sevil, Arslan Ayla, Gülümser Çisil, Topkaya Eylem, Kurtkulak Hatice, Zeybek Şehriban, Dimoglo Anatoli, İşgören Melike

Journal of Ecological Engineering

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2019

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Vol. 20, nr 10

165--171

EN

In Turkey, the commercial laundry wastewater is usually discharged to the receiving water bodies and its reuse potential is ignored. This wastewater is grouped into the greywater due to their content of organic and inorganic pollutants. In recent years, the sequential processes have become more preferable in greywater treatment and reuse. In this study, a batch adsorption process was applied for further treatment of commercial laundry wastewater which is also pre-treated by means of the electrocoagulation process. In adsorption, two different composites of waste hazelnut shell derived activated carbons, which are supported with polyaniline (PAn/HS) and polypyrrole (PPy/HS), were used as adsorbents. The efficiency of the process was evaluated by means of an experimental design, and the response surface methodology was applied for this purpose. In the experiment with PAn/HS, the chemical oxygen demand (COD) 75% removal efficiency was accomplished with adsorbent dosage of 0.9 g, at pH 8, with 125 rpm mixing rate and for 77.5 min reaction time. For PPy/HS under the same experimental conditions, the COD removal efficiency was obtained as 20%. The utilization of waste hazelnut shell derived composites as adsorbents for commercial laundry wastewater treatment is a good alternative. The production costs of adsorbents were estimated as 0.70 USD/g and 3.21 USD/g for PAn/HS and PPy/HS, respectively. In terms of the production cost, the PAn/HS composite is approved more agreeable as adsorbents for commercial laundry wastewater treatment.

7

Treatment of Medical Wastewater by Moving Bed Bioreactor System

Jasem Y. I., Jumaha G. F., Ghawi A. H.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 3

135--140

EN

The hospital wastewater is considered as a complex mixture, populated with microbial and a variety of toxic substances. The performance of EEC USA moving bed biofilm reactor (MBBR) with polyethylene media as biofilm support carrier, packaged wastewater treatment plant with a capacity of 250 m(3)/day was evaluated for treating the wastewater from Al-Batul hospital of Baquba city in Iraq in terms of the organic matter and suspended solid removal, along with nitrification and microbial growth for medical wastewater. The test results showed that the average removal efficiency of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solid (TSS) were 79.5%, 74.5%, and 78%, respectively. The system offers good nitrification with the efficiency of 79%. The system shows a weak formation of biomass on carriers, only 1.93 g TSS/m(2) of media, corresponding to 32% of the suspended biomass in the reactor.

8

Treatment of evaporative water from brewer’s yeast concentration by Fenton and Fenton-like processes

Michel M. M., Reczek L., Siwiec T., Rudnicki P.

Archives of Environmental Protection

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2018

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Vol. 44, no. 3

11--18

EN

Evaporative water from yeast slurry concentration is acidic, low mineralized and contains large amounts of dissolved organic contaminants. The treatment of evaporative water from yeast slurry concentration by Fenton (Fe(II)/H2O2) and Fenton-like (Fe(III)/H2O2) reactions has been studied. The processes in terms of system variables have been compared: catalyst and oxidant doses, initial pH, temperature of reaction, and the reaction kinetic. For determination of mineralization efficiency the total organic carbon (TOC) in water before and after reactions was measured. The Fenton reaction was more efficient for mineralization of organic compounds: the highest efficiency of TOC removal was 45–50%, while for the Fenton-like it was 20–30%. The pH adjustment of evaporative water in the range of 2–5 did not change the efficiency of treatment. Temperature of 30°C was the most favorable for both reactions. The Lumped Kinetic Model fitted very well the experimental results. The reaction rate analysis indicated that the rate of direct mineralization of organic compounds is similar to the rate of its oxidation to organic intermediates, its selectivity factor was more favorable to the Fenton reaction. The strong correlation between chemical oxygen demand (COD) and TOC in evaporative water after the Fenton and Fenton-like reactions has been determined, providing a simple tool for calculating COD on the basis of values of TOC measurement.

PL

Woda wyparna z zatężania gęstwy drożdżowej jest kwaśna, nisko zmineralizowana i zawiera dużą ilość rozpuszczonych związków organicznych. W pracy badano oczyszczanie wody wyparnej w reakcji Fentona (Fe(II)/H2O2) i pokrewnej (Fe(III)/H2O2). Porównywano procesy przy następujących zmiennych: dawki katalizatorów i utleniacza, pH początkowe, temperatura i kinetyka reakcji. Efektywność oceniano poprzez pomiar ogólnego węgla organicznego przed i po reakcji. Związki organiczne były bardziej skutecznie mineralizowane w reakcji Fentona: najwyższa efektywność usuwania OWO wynosiła 45–50%, a w reakcji pokrewnej jedynie 20–30%. Korekta odczynu wody wyparnej w zakresie 2–5 pH nie wpłynęła na efektywność oczyszczania. Temperatura 30°C była najbardziej korzystna dla obydwu reakcji. Model kinetyczny o parametrach skupionych bardzo dobrze opisywał wyniki badań eksperymentalnych. Analiza szybkości reakcji wykazała, że jest ona zbliżona w przypadku mineralizacji organicznych składników oraz utleniania do produktów pośrednich, a współczynnik selektywności reakcji był korzystniejszy dla procesu Fentona. Określono silną korelację pomiędzy parametrami ChZT i OWO w wodzie po reakcji Fentona i pokrewnej, co może być przydatnym do obliczania ChZT na podstawie pomiaru OWO.

9

Zastosowanie procesu Fentona do oczyszczania ścieków garbarskich

Przywara L.

Inżynieria Ekologiczna

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2017

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Vol. 18, nr 2

117--122

PL

W artykule omówiono badania, których celem było określenie efektywności oczyszczania ścieków garbarskich w procesie pogłębionego utleniania z zastosowaniem odczynnika Fentona. Proces przeprowadzono stosując różne dawki żelaza zmieniane w zakresie od 0,056 g Fe2+/dm3 do 0,56 g Fe2+/dm3, H2O2od 0,34 g/dm3 do 5,44 g/dm3 i w zakresie pH od 2,5 do 3,5. Ścieki scharakteryzowano wykonując oznaczenia podstawowych wskaźników fizyko-chemicznych (pH, przewodność, ChZT, chrom, azot amonowy). Badano także możliwość zastosowania procesu koagulacji przy użyciu koagulantu SAX 18. Efektywność procesu określono w oparciu o zmiany głównie wartości zanieczyszczeń organicznych określonych jako ChZT. Skuteczność procesu Fentona prowadzonego dla dawki Fe2+ na poziomie 0,56 g Fe2+/dm3i H2O2 4,08 g/ dm3 wynosiła 80% zmniejszania ChZT w stosunku do ścieków surowych i była wyraźnie wyższa niż w przypadku procesu koagulacji.

EN

The aim of this study was to treat of tannery wastewater with the chemical advanced oxidation using Fenton reagent. Advanced oxidation process was carried out using different doses of iron (Fe2+) changes from 0.056 g Fe2+/dm3to 0.56 g Fe2+/dm3and H2O2from 0.34 g/dm3 to 5.44 g/ dm3. The wastewater samples were characterized for the concentration of chemical oxygen demand (COD), chromium, ammonia and pH, conductivity. The possibility of using the coagulation process using SAX 18 was also investigated. The efficiency of the applied processes was monitored by change mainly of chemical oxygen demand (COD). The maximum COD removal was 80% for Fenton’s oxidation process at pH 3.0, Fe2+ (0.56 g Fe2+/ dm3) and H2O2 (4.08 g/ dm3) and significantly higher than in the case of the coagulation process.

10

Phosphorus and COD removal from chemically and electrochemically coagulated wastewater

Smoczyński L., Muńska K. T., Kosobucka M., Pierożyński B.

Environment Protection Engineering

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2014

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Vol. 40, nr 3

63--73

EN

Wastewater coagulation and electrocoagulation were investigated as sorption processes involving colloidal sorbents such as (Al(OH)3)n, (Fe(OH)3)m and (Fe(OH)2)p. An attempt was made to fit experimental data to two popular sorption models. Based on a statistical and mathematical analysis of the obtained results, the Langmuir model of chemical adsorption was regarded more probable than the Freundlich model. The highest maximum adsorption of phosphorus in the analyzed wastewater was achieved with the use of PIX, and the lowest adsorption maxima were reported for an iron electrocoagulant. PAC was most effective in reducing COD of wastewater. PAC and PIX delivered higher adsorption maxima for compounds responsible for COD than aluminum and iron electrocoagulants.

11

Simultaneous decolorization of ternary dye mixture from aqueous solution by electrocoagulation

Keskin C. S., Özdemir A., Karabayir E., Şengil I. A.

Environment Protection Engineering

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2013

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Vol. 39, nr 3

119--133

EN

The current study focused on the treatment of a ternary mixture of dyes which includes Disperse Blue 56 (DB56), Basic Yellow 28 (BY28) and Acid Violet 90 (AV90) using the electrocoagulation (EC) process with iron electrodes. In the presence of all dye molecules, the optimum pH was found to be 6, optimum NaCl concentration was 3000 mg/dm3 and optimum current density was 8.66 mA/cm2. Under the optimized conditions in the case of 100 mg/dm 3 each dye concentration, the average colour removal efficiency was reached 93%. Dye concentration dependent highest COD removal efficiency was measured as 88.70% at 150 mg/dm3 dye concentration.

12

COD removal from landfill leachate using H2O2, UV radiation and combination these processes

Pieczykolan B., Barbusiński K., Płonka I.

Environment Protection Engineering

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2012

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Vol. 38, nr 3

5--13

EN

Experiments for removal of organic compounds (expressed as COD) from "young" municipal landfill leachate, using oxidation by H 2O2, UV photooxidation and UV/H 2O2 process, were carried out on a laboratory scale. Studies have shown that the most effective method was UV/H 2O2 process. When oxidation was conducted under the most suitable conditions (parameters found during experiments), maximum value of COD removal equaled 74.6%, 19.6% and 19.3% when the treatment was realized by use of H 2O2/UV, H 2O2 and UV radiation, respectively. These results demonstrate that in order to attain high efficiency of COD removal, use of advanced oxidation process (H 2O2/UV) is necessary.

13

Tannery wastewater treatment by anodic electrooxidation coupled with electro-Fenton process

Naumczyk J., Kucharska M.

Environment Protection Engineering

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2011

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Vol. 37, nr 3

47-54

EN

Investigations were performed on tannery wastewater, previously coagulated with FeCl3. An electrolyzer was equipped with two graphite cathodes and Ti/SnO2/PdO2/RuO2 anode, divided by the diaphragm made of asbestos fibre. The current density was: cathodic 2.0 A/dm2 and anodic 2.1 A/dm2. After 55 min of the process the catholyte was transferred into the anodic space and the process was continued. After 55 min of electro-Fenton process, the COD was reduced by 52.0% (current efficiency of COD removal was 10.6%). Electrooxidation continued by the anodic process resulted in elimination of ammonia in 55 min and a total reduction of COD by 72.9%. The coupled process d could be considered a simulation of the combined process under flow conditions. The effect of this process was compared to that of a two-steps process: Fenton process followed by indirect anodic oxidation.

14

Oczyszczanie ścieków z produkcji płyt pilśniowych w reaktorze UASB

Neczaj E., Krzemińska D.

Inżynieria i Ochrona Środowiska

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2010

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T. 13, nr 2

111-120

PL

Najważniejszym wyzwaniem w ramach procesu oczyszczania ścieków z produkcji płyt pilśniowych jest zmniejszenie zawartości w nich związków organicznych, zawiesin oraz intensywności barwy. W ostatnich latach wzrosło zainteresowanie technologiami beztlenowymi w oczyszczaniu tego rodzaju ścieków. Za stosowaniem systemów anaerobowych przemawia: mniejsza produkcja osadów ściekowych, możliwość oczyszczania ścieków wysokoobciążonych ładunkiem zanieczyszczeń, wytwarzanie energii w postaci metanu. W pracy przedstawiono wyniki badań nad możliwością zastosowania reaktora UASB w oczyszczaniu ścieków z produkcji płyt pilśniowych. Badania prowadzone były w skali laboratoryjnej w warunkach mezofilowych przy stałym hydraulicznym czasie zatrzymania, wynoszącym 3 doby, i obciążeniu substratowym w przedziale 1,3 ÷ 2,5 kgChZT/m³d. Efektywność procesu oczyszczania oceniono na podstawie stopnia usunięcia ChZT oraz produkcji biogazu. Najlepsze wyniki uzyskano przy obciążeniu substratowym reaktora wynoszącym 2 kgChZT/m³d. Dla podanych warunków prowadzenia procesu odnotowano 66% usunięcie ChZT oraz produkcję biogazu na poziomie 0,38 dm³/gChZTus d.

EN

The effluent from fiberboard manufacturing (FBM) is a specific kind of wastewater with the COD value of over 20 000 mg/l and a suspended solids content of more than 1500 mg/l. The organic components of the effluent include cellulose, lignin and resin acids. The high COD content present in this wastewater makes it suitable for anaerobic treatment however the presence of toxic or recalcitrant substances implies an additional challenge for developing a reliable biological process. Increased gas production and reduced excess sludge generation significantly improve the economics of anaerobic digestion. The concept of the Upflow Anaerobic Sludge Blanket (UASB) reactor is very simple. The reactor consists of a chamber in which the wastewater flows upward through an anaerobic sludge bed and passes in contact with the micro-organisms. In result and anaerobic degradation of the wastewater organic matter occurs. The produced biogas causes hydraulic turbulence as it moves upward through the reactor, providing adequate mixing within the system and eliminating the need for mechanical mixing. The presence of a three-phase separator at the top of the reactor, allows separation of the water phase from sludge solids and gas. In this study the treatment of fiberboard manufacturing (FBM) wastewater was carried out in a laboratory scale UASB rector. Bioreactor performance was evaluated by COD removal efficiency and biogas yield. The aim of the work was to determine the optimal organic loading rate (ORL) for a hydraulic retention time (HRT) of 3 days. The ORL range from 1.3 to 2.5 kgCOD/m³d was studied. 66% of COD removal efficiency and biogas yield of 0.38 m³biogas/kgCODremovedd were obtained in the anaerobic reactor operating at 37°C when OLR was equal to 2 kgCOD/m³d.

15

Oczyszczanie ścieków z produkcji płyt pilśniowych wspomagane polem ultradźwiękowym w reaktorze SBR

Grosser A., Kamizela T., Neczaj E.

Inżynieria i Ochrona Środowiska

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2009

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T. 12, nr 4

295-305

PL

Przedstawiono wyniki badań nad możliwością oczyszczania mieszaniny ścieków syntetycznych o składzie odpowiadającym ściekom bytowo-gospodarczym i ścieków z produkcji płyt pilśniowych w reaktorze typu SBR. Dokonano oceny efektywności procesu na podstawie stopnia obniżenia wartości ChZT dla danych parametrów procesowych: czas zatrzymania tz (2, 4, 6, 8 d), udział objętościowy ścieków przemysłowych w mieszaninie (5, 7, 9%), amplituda oraz czas nadźwiękawiania ścieków przemysłowych (22,4 µm i 12 min oraz 48,8 µm 4 min). Badania były prowadzone w 4 reaktorach pracujących w 24-godzinnym cyklu pracy, złożonym z następujących faz procesowych: napełniania i mieszania, reakcji - mieszania i napowietrzania, mieszania, sedymentacji i dekantacji oraz przestoju. Wykonane w ramach pracy badania potwierdziły możliwość zastosowania pola ultradźwiękowego do współoczyszczania mieszaniny ścieków z produkcji płyt pilśniowych i ścieków syntetycznych. Efektywność oczyszczania ścieków wyrażona obniżeniem wartości ChZT rosła wraz ze wzrostem czasu przetrzymania ścieków w reaktorze tz lub obniżaniem obciążenia reaktorów ładunkiem zanieczyszczeń oraz zmniejszaniem udziału ścieków przemysłowych w mieszaninie doprowadzanej do reaktora. Na efektywność oczyszczania miały wpływ parametry pola ultradźwiękowego. We wszystkich reaktorach odnotowano przy zastosowaniu do kondycjonowania pola o amplitudzie 22,4 µ m i czasie ekspozycji 12 min poprawę jakości ścieków oczyszczonych oraz obniżenie wartości wskaźnika ChZT ścieków surowych w porównaniu do wyników uzyskanych dla amplitudy drgań 48,8 µm.

EN

The paper presents the results of research on co-treatment of fibreboard industry wastewater mixed with synthetic wastewater. The experiment was made in a SBR reactor. Process efficiency has been estimated basing on COD (Chemical Oxygen Demand) changes with the following process parameters: retention time (2, 4, 6, and 8 d), industrial wastewater participation in the wastewater mixture (5, 7, and 9%), industrial sewage sonification time and amplitude (24.4 µm 12 min, and 48.8 µm, 4 min). During the first stage of the research the influence of process parameters on the COD removal was studied. Industrial wastewater was prepared by means of ultrasonic field with amplitude of 48.8 µm for 4 minutes. The analysis of changes of COD removal in sewage indicated the effectiveness treatment increase, resulting from lengthened sewage retention time in the reactor. It was also observed that the increase of industrial sewage volume fraction in the wastewater mixture resulted in the decrease of organic compound removal effectiveness and lowering of the treated sewage quality. At the next stage of research the influence of industrial sewage sonification condition on treatment effectiveness was examined. The comparison was carried out for a wastewater mixture with 9% (v/v) of industrial sewage content. The vibration amplitude was dropped from 48.8 to 24.4 µm, and the exposition time was lengthened from 4 to 12 minutes. After conditioning with a 22.4 µm ultrasonic field amplitude through 12 min the increase of the treated sewage quality was observed. In comparison to the results achieved with a 48.8 µm amplitude ultrasound field, the decrease of COD value was noted. It was also observed that the change of conditions of sonification with an ultrasound field of raw industrial sewage resulted in the decrease of sewage COD index by 124 mgO2/dm3.

16

Non-circular ceramic membranes for use in wastewater treatment

Chiu T. Y., Lara Dominguez M. V., James A. E.

Environment Protection Engineering

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2005

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Vol. 31, nr 3-4

53-60

EN

An extensive use of membrane bioreactors in wastewater treatment often produces the effluent quality far beyond the current regulatory requirements for discharge to the environment. However, like other processes involving membranes, the severest constraint is the problem of fouling, the extent of which can be reduced by changing the flow pattern (maintaining in turbulent conditions) within the channels. In this study, the treatment of effluent from synthetic sludge production was investigated employing membrane bioreactors utilising non-circular multi-channelled membranes. Very high chemical oxygen demand (COD) and suspended solids (SS) removals were obtained for the range of pore sizes employed, up to 94% and 98%, respectively. As the pore size was increased, a decrease in efficiency was observed. Differences in the rejection behaviour are attributed to the difference in the characteristics of cakes which were formed. Specific cake resistance seems to increase moderately with diminishing pore size. The critical flux was found to be dependent on cross-flow velocity, introduction of inserts and pore size. Critical flux increased to about 82.5 l m-2 h-1 at a cross-flow velocity of 2.0 m s-1. The high critical flux can be attributed to the non-circular geometry of the channels which seems to promote turbulent flow, depolarising the solute built-up, even at low cross-flow velocity. Finally, the present paper demonstrates ways in which hydrodynamics and colloid interactions affect the critical flux.

17

Możliwości podczyszczania odcieków z wysypisk metodami biologicznymi

Surmacz-Górska J., Miksch K., Kita T.

Archiwum Ochrony Środowiska

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2000

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Vol. 26, no. 3

43--54

PL

Odcieki wysypiskowe są to wody deszczowe migrujące przez złoże wysypiska, wymywające z niego rozpuszczalne frakcje organiczne i mineralne zawarte w składowanych odpadach. Trzyletnie badania odcieków pochodzących ze składowisk odpadów komunalnych w Siemianowicach Śląskich i Dąbrowie Górniczej wykazały, że ChZT odcieków na ogół waha się między wartościami 1000 i 2000 mg/dm3, a w nielicznych okresach w roku przekracza te wartości osiągając stężenia nawet powyżej 14000 mg ChZT/dm3. W przypadku, gdy stężenie ChZT odcieków jest niskie i nie przekracza 2000 mg/dm3, mamy do czynienia ze związkami trudno rozkładalnymi biologicznie. Odmienną sytuację obserwowano, gdy ChZT odcieków znacznie przekraczało typowe niskie wartości. Napowietrzanie odcieków z osadem czynnym powodowało szybki rozkład związków organicznych i spadek ChZT. Już po 5 godzinach napowietrzania uzyskano 75% obniżenie stężenia ChZT. Typowym zjawiskiem przy oczyszczaniu odcieków była nitryfikacja wysokich stężeń azotu amo-nowego, zachodząca bez zakłóceń w obecności dużych ładunków związków organicznych. Bardzo ważnym zjawiskiem był brak wpływu toksycznego na bakterie nitryfikacyjne zarówno odcieków z Siemianowic Śląskich, jak i z Dąbrowy Górniczej.

EN

Landfill leachates are generated by rainwater passing through the landfill and washing out organic and mineral compounds from the disposed wastes. Three-year-research of landfill leachates originated from the landfills in Siemianowice Ślaskie and Dąbrowa Górnicza showed that COD of landfill leachates varied from 1000 to 2000 mg/dcm3. Only sporadically COD was higher and reached values even above 14ooo mg/dm3. If COD of raw leachates was low and did not exceed 2000 mg/dm3, organics in leachates were not biodegradable. The opposite situation was observed when COD was high and exceeded normal val-ues. Aeration of the leachates with activated sludge resulted in rapid decomposition of organic compounds and COD decrease. After 5 hours of aeration 75% of COD reduction was obtained. During the landfill leachates treatment nitrification of high concentration of ammonia nitrogen was observed even in the presence of high load of organic compounds. Moreover, landfill leachates from Siemianowice Ślaskie and Dąbrowa Górnicza have had no inhibitory effect on nitrifying bac-teria.