Initial COD Concentration Research Articles

Investigation on the Efficiency of Modified Fenton on the Treatment of Leachate Generated From Oily Sludge Composting

Background: and Aim The leachate from oil sludge compost into the environment, which is resistant to decomposition, causes several environmental problems. Therefore, it needs to be treated using efficient processes. This study aimed to investigate the efficiency of the modified Fenton process for treating these oil sludge leachates. Methods & Materials: In this experimental study, leachate samples were collected, and then modified Fenton solution was prepared by adding Fe2 (SO4) 3 to H2O2. Then the effect of time parameters (15, 30, 60, 90, and 120 minutes), modified Fenton concentration of 20, 50, 100, and 200 mg/l with pH 3, 5, 9, and three initial concentration of COD (500, 1000 and 1500 mg/l) was examined. Ethical Considerations: This study has been registered in Arak University of Medical Sciences with codes 2645 and 2765. Results: The reduction of COD and TPH in the optimal time of 60 minutes, initial COD of 500 mg/l, pH of 3, and Fenton concentration of 200 mg/l were 9.04 and 77.42%, respectively. The experiments showed that the removal efficiency of COD and TPH with increasing residence time and the concentration of modified Fenton are directly proportional and with decreasing, the initial concentration of COD and pH is inversely proportional. Conclusion: The use of modified Fenton is an efficient method for treating leachate from petroleum sludge compo

Energy efficient removal of COD from landfill leachate wastewater using electrocoagulation: parametric optimization using RSM

In the present work, electrocoagulation method was employed using iron/aluminium electrodes for COD removal in the treatment of landfill leachate. The process was optimized with variables such as initial pH, applied current, initial COD and electrolysis time experimentally varied as per CCD design to know their influence on chosen response variables viz. COD removal efficiency and electrical energy consumption. The optimum conditions found were pH 5, applied current 0.5 A, initial COD concentration 5450 ppm and application time 9 min to achieve 64.25% efficiency with 0.59 W hour per gram removal of COD. The results prove that electrocoagulation process could be suitably used as an effective method for treatment of leachate. Operating cost of optimized condition was figured out as Indian rupee 0.211 (equivalent to 0.0028 US $) per gram of COD removed.

Electro-peroxone treatment of rice grain based distillery biodigester effluent: COD and color removal

This work attempts to treat biodigester effluent (BDE) using electro-peroxone processes with respect to COD and color removal. During the process aluminium is used as anode and carbon-PTFE (polytetrafluoroethylene) is used as cathode with the combination of ozone. Experiments are performed at different conditions such as changing cathode material and electrolytes. At the optimum condition COD and color removal efficiency achieved was 99.9% and 91.3%, respectively with 3.8 kWh/m3 of energy consumption, current density of 32 A/m2, initial COD concentration of 6000 mg/dm3, initial pH of 6, O3 concentration of 135 mg/dm3, Na2SO4 concentration of 0.15 M, stirring speed of 100 rpm, and electrolysis time of 50 min in the electro-peroxone process. Finally, potential of electro-peroxone process, sludge analysis and cost optimization are also described in the present article.

Optimization of aeration time on GAS-SBR system to remove organic content in wastewater

In general, chicken slaughterhouses have slaughtering capacity of more than 40,000 chickens per day, resulting in high volume wastewater with high BOD and COD concentration. Therefore, appropriate wastewater treatment technology is needed. Granular Activated Sludge that uses Sequencing Batch Reactor (GAS-SBR) has ability to treat wastewater with high organic content. The study is conducted to analyze the ability of GAS to reduce organic content with variation of aeration time in reaction stage on SBR. Formation of Granular Activated Sludge (GAS) was cultured by reacting activated sludge and using a stirring of 20 rpm. SBR had a total work volume of 45 liters and was operated in 5 stages, namely the filling, the reaction with aeration, the settling, the decantation, and the stabilization stage. In this study the initial COD concentration in chicken slaughterhouse effluent (RPA) was 5440 mg/L. The result of the study was that highest removal of BOD and COD parameter occured at 3 hours’ aeration time with removal efficiency 75% and 72%, while for TSS was at 5 hours’ aeration time with removal efficiency 65%. It could be concluded that GAS in SBR system could be applied to remove high organic content parameters in wastewater.

Ethanol production from waste glycerol using glucose as co-carbon source

Ethanol was produced by sole glycerol and glycerol-glucose fermentation using Enterobacter aerogenes TISTR 1468. The initial experiment was set up with waste glycerol as a sole carbon source with initial concentration ranged from 0, 8.7, 23.4, 43.4, to 63.1 g L−1 in 100-mL serum bottles under controlled condition at 30°C for 240-hr fermentation. Liquid samples, during the fermentation, were collected to quantitate concentrations of volatile fatty acids and glycerol, whilst gaseous samples were collected to quantitate CO2 and CH4 constituent. E. aerogenes TISTR 1468 produced maximum ethanol concentration and yield of 215.1 mM and 0.71 mol mol−1 after 72-hr fermentation with the initial waste glycerol concentration of 63.1 g L−1 (equivalent to 79.11 g COD L−1). The ethanol production from glycerol-glucose fermentation was set up based on the initial COD concentration equivalent to 79.11 g COD L−1 with varying glycerol-glucose ratios of 1:1, 10:1, and 100:1. At the ratio of 100:1, maximum ethanol concentration and yield were 232.8 mM and 0.59 mol mol−1 after 24-hr fermentation. Addition of glucose as co-carbon did improve ethanol concentration.

Research On the Change of Rainwater Quality in the Early Stage of River Discharge

The primary rainwater non-point source pollution is one of the main pollution reasons affecting river water quality. Based on the comprehensive analysis of the rainfall data, initial rainwater quality data and catchment area data, this paper obtains the variation rules and pollution characteristics of the initial rainwater quality at different catchment ranges of river outfall, and provides suggestions for the control of primary rainwater non-point source pollution of the target river outfalls. In the target River outlet of this study, the commercial area is the first to reach the peak of COD and ammonia nitrogen in the initial rainwater quality, and the living area is the highest in the initial rainwater COD and ammonia nitrogen concentration. Thus the control measures can be taken for the initial rainwater in the commercial area, and the key prevention and control measures can be taken for the higher concentration initial rainwater in the living area.

Optimization of acetate production from citrus wastewater fermentation

Citrus wastewater is a sugar-rich waste stream suitable for the recovery of energy of material from its treatment. In this study, fermentation of citrus wastewater was carried out to assess the optimal conditions to maximize the bioconversion of the organic substrate into acetate. Unbalanced nutrient (C: N: P 200:0.1:0.1) enabled the highest acetate production. The presence of the particulate organic fraction enabled to obtain a higher acetate concentration regardless the initial COD concentration. Initial pH values higher than 5 did not cause substantial differences on the maximum bioconversion of COD into acetate, whereas pH lower than 5 hindered the hydrolysis process. Lastly, the bioconversion rate of the organic substrate into acetate decreased from a maximum of 23% to a minimum of 8% related to the initial COD. The achieved results demonstrated that the characteristics of citrus wastewater enable its valorisation without the need to apply energy-consuming processes.

From the accelerated production of •OH radicals to the crosslinking of polyvinyl alcohol: The role of free radicals initiated by persulfates

Persulfates are the concerned oxidants in the advanced oxidation processes recently. Besides, persulfates with higher concentrations can initiate the free radical crosslinking of the polymeric chain, which is considered as one of the solutions for the pollution control of soluble polymers. In this study, the combination of free radical crosslinking and oxidation initiated by a thermally activated persulfate system was used to simultaneously remove polyvinyl alcohol (PVA) and the coexisting organic pollutants, i.e. dyes. Especially, the catalyst-like function of PVA could accelerate the production of OH radicals via the elimination of −OH groups. It can promote the crosslinking itself and facilitate the degradation of coexisting pollutants. Given initial COD and PVA concentrations of 14406.0 mg/L and 8063.2 mg/L, respectively, a maximum of 93.6 % COD and 98.4 % PVA was removed under the optimal conditions. Meanwhile, the PVA with high concentration did not have negative effects on the degradation of coexisting pollutants.

High Efficiency of Waste Stabilization Ponds using Para Grass (Brachiaria Mutica) Vegetation for Treatment of Industrial Wastei Ho Chi Minh City, Vietnam

In recent years, wastewater treatment by using biological method has been concerned because it low cost, easy to operate and enviromentally friendly. In this study, stabilization pond – one of the biological wastewater treatment methods has been researched for treating industrial wastewater in Industrial park, District 2, Ho Chi Minh city, Viet Nam. In stabilization pond, Para grass planted on the surface of the pond with roots in the water. Important elements of the treatment process were surveyed to provide optimal operation conditions, include: flow rate of influent, grass cutting cycle, initial COD concentration, fraction of N and P, the height of Para grass after cutting, pH in influent. The results show that Para grass grows well in wastewater and treatment efficiency of stabilization is high when flow rate of influent at 0.12 m3/h and 0.18 m3/h (corresponding to retention time is 7.8 days and 5.3 days, respectively). Besides, Para grass need to be cut periodically for about 20-22 days and the height of grass after cutting from 0.2 - 0.4 m to ensure the best treatment efficiency. Effect of pollution parameters of influent has been also surveyed. The results showed that stabilization pond treats wastewater efficiently when the initial COD concentration is from 200 to 350 mg/l, the fraction of N/P is from 4 to 6 and pH= 7. Wastewater after treatment with stabilization pond meets standards QCVN 40:2011/BTNMT (National Technical Regulation on Industrial Wastewater) with parameters in effluent such as COD, TN, TP, BOD5, Coliform. Moreover, biomass of Para grass after treatment can be used as feed source for livestock and ensure safety according to QCVN 01-183:2016/BNNPTNT. These results show the applicability of stabilization pond using Para grass vegetation in concentrated industrial wastewater treatment with low cost, simple but efficiency, environmentally friendly and towards sustainable development.

Effect of initial cod concentration and the fraction of N/P on treatment ability of Para grass (Brachiaria mutica) vegetation in the stabilization pond

Stabilization pond which is covered by aquatic plant is a environmentally friendly method to treat wastewater. In this study, stabilization pond using Para grass vegetation is applied to treat industrial wastewater and study the effect of intitial COD concentration and the N/P ratio on treatment abliity of para grass vegetation in the stabilization. The influent flow rate is controlled at 0.18 m3/h (corresponding to a retention time of 5.3 days). As inflow COD concentration is 203 ± 5.9 mg/L, COD treatment efficiency reaches 59.6 – 61.7%. When COD concentration in the input wastewater is 349.2 ± 4.5 mg/L, COD removal efficiency decreased to 55.7 0.9%. Continue to increase input COD concentration in the input to 512,6 ± 14,7 mg/l, COD treatment efficiency reduce to 47.9±0.6%. However, when increasing the input COD concentration corresponding to increasing the organic loading rate into the model, reached 10.270 kgCOD/ha.day at COD concentration = 512.6 ± 14,7 mg/L, twice higher than the organic loading rate of the model since COD concentration = 203 ± 5.9 mg/L. The result shows strong adaptability and wastewater treatment ability of facultative waste stabilization pond system covered by Para grass, although the input COD concentration or organic load increase more than doubled. The study also showed that the treatment efficiency of total nitrogen (TN) tends to increase when COD concentration in influent increases, with treatment effiency has reached from 57.2 to 76.4%. Besides, the fraction of nitrogen and phosphorus in influent also surveyed in this study. The fraction of N/P selected to survey in the study is approximately 2.26, 4.16 and 6.11. The results show that when increasing the N/P ratio, the efficiency of Total Nitrogen treatment tends to increase. At N/P ratio = 2.26 ± 0.19, even though the concentration of TN in the inlet is low, but nitrogen metabolism still takes place in the experimental model, so outlet TN concentration decrease to very low. The COD treatment efficiency increases gradually when increasing the N/P ratio. The output COD match Vietnam discharge standard QCVN 40:2011/BTNMT. These results show potential for applying the stabilization pond which is covered by Para grass for treating concentrated industrial wastewater.

Treatment of oil and grease in wastewater using Electrocoagulation (Dept. C (Public Works ) )

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Research on the Contaminants Adsorption and Removal by Macroporous Resins in the Textile and Dyeing

Textile and dyeing wastewater is the major source of environmental water pollution all over the world, which has complex composition so that conventional methods are difficult to remove and degrade. Based on the relevant research, this paper proposes to add further treatment by using macroporous resins on the basic of the conventional treatment and explore the effects of the adsorption and desorption, such as the pH value, initial concentration of , temperature and the flow rate. The performance of six kinds of macroporous resins (DA-2, D280, DA201, D3520, AB-8 and DA-201) for the advanced treatment in the textile and dyeing wastewater has been evaluated. The adsorption and desorption properties of the contaminants, which tested by the six kinds of the macroporous resins in the textile and dyeing, have been compared. According to the results, D3520 resin holds the highest adsorption and desorption capacity. (15.6mg/g for adsorption capacity, 15.1mg/g for desorption capacity). The effects of the pH value, initial concentration of , temperature and the flow rate on removal of by D3520 macroporous resin have been tested. The results showed that the removal of increased with the pH value and initial concentration of COD increasing and the data of its adsorption fitted the Langmuir isotherm best. Besides, 92.49% could be removed after 8h of adsorption at 25 °C. Dynamic adsorption and desorption experiments have been carried out on the packed column of D3520 resins as a reference for engineering applications, the results showed that the D3520 resin could still reach 79.5% removal rate after adsorptions-regeneration for five times.

Aerobic sludge granulation in shale gas flowback water treatment: Assessment of the bacterial community dynamics and modeling of bioreactor performance using artificial neural network

Flowback water from shale gas extraction is highly saline and comprises complex organic substances, thereby posing a significant challenge for the environmental management of the unconventional natural gas industry. In this work, an aerobic granular sludge (AGS) method was successfully used for the treatment of flowback water from shale gas extraction. The formed AGS had a diameter of 0.25–2.0 mm and the total sludge volume index was 23.40 mL g−1. The AGS efficiently removed COD, NH4+-N and TN by 70.1%, 92.1%, and 59.2%, respectively. The bacterial communities responsible for the removal of nitrogen and degradation of organics were enriched in AGS. The dynamics of contaminant removal was further explained with a three-layered artificial neural network model. The results showed that the initial concentration of COD, TDS, NH4+-N and TN governed the contaminants’ removal. As for operating parameters, aerating time showed a strong effect on NH4+-N and TN removal, whereas settling time impacted the COD removal.

Denitrification of low C/N landfill leachate in lab-scale landfill simulation bioreactors

Old landfill leachate can be characterized by high ammonia nitrogen concentrations and limited biodegradable carbon availability. A promising and cost-effective option for ammonia nitrogen removal involves ex situ nitrification and in situ denitrification.This study aimed to investigate the denitrification capacity of old MSW in six landfill bioreactors with very low COD/NO3−-N mass ratios that ranged between 0.12 and 3.99 g/g. In particular, this study is novel in that it tested COD/NO3−-N mass ratios lower than previous studies. The experiment lasted 83 days. The results showed that denitrification occurred in all bioreactors and even at considerably low concentrations of biodegradable organic matter (BOD5 ≤ 9 mg O2/L). In all but one case, when nitrate removal stopped at 55% due to the absence of leachate recirculation, nitrate removal was higher than 95%.The average nitrate removal rates (ANRRs), calculated under significantly different conditions, ranged from 33 to 135 mg NO3−-N/L/d. The initial COD concentration and COD/NO3−-N ratio did not appear to affect the ANRRs, which were influenced by the initial nitrate concentration and leachate recirculation. The maximum ANRR (135 mg NO3−-N/L/d) was measured with the highest initial nitrate concentration (4491 mg NO3−-N/L) and the lowest COD/NO3−-N mass ratio (0.12 g COD/g NO3−-N). The lowest ANRR (33 mg NO3−-N/L/d) was calculated for a bioreactor with no leachate recirculation.Sulphate production observed in some bioreactors may suggest that, together with the heterotrophic pathway, autotrophic denitrification contributed to the removal of nitrate, especially in bioreactors with low COD/NO3−-N mass ratio.

Start-up Characteristics of SNAD Process and Functional Abundance Succession of Volcanic Rock Biological Aerated Filter

A SNAD(simultaneous partial nitrification,ANAMMOX,and denitrification) process initiated in a submerged biological aerated filter (SBAF) was started up by seeding nitrification sludge and an ANAMMOX filter to investigate the operating characteristics and the succession of functional bacteria. The results showed that when the autotrophic nitrogen removal and denitrification were operated stably for 67 days at an initial COD concentration of 60 mg·L-1, the maximum nitrogen removal efficiency, the COD removal rate, and the nitrogen removal rate were 92.0%, 82.9%, and 2.3 kg·(m3·d)-1, respectively. Moreover, the total nitrogen removal rate of the SNAD process in this study was 12.6% higher than that of CANON process. The results of quantitative PCR showed that the abundance of AOB slightly increased, while the abundance of ANAMMOX was one order higher than that before the start-up of SNAD. In comparison, the abundances of denitrifiers and NOB remained at a relatively low level (107 copies·g-1). Taken together, these results suggested that the SBAF process with volcanic filter was beneficial for the accumulation of ANAMMOX and AOB.

Prevention of substrate and product inhibitions by using a dilution strategy during dark fermentative hydrogen production from molasses

Substrate and product inhibitions have a significant effect on dark fermentative hydrogen gas production. Particularly, rapid formation of volatile fatty acids leads to fast pH decreases shifting the metabolic pathway. Therefore, controlling volatile fatty acid accumulation has great importance in maintaining effective hydrogen production. In this context, a dilution strategy was applied to regulate volatile fatty acids levels within the desired concentration range. A three-factor Box-Behnken statistical experiment design was established to assess the effects of dilution time, dilution percentage and initial COD concentration on hydrogen formation yield and rate. Highest hydrogen yield (7.7 mL H2/mLreactor) and rate (21. 47 mL H2/h or 9.38 mmol/Lreactor.h) were achieved when 85 gCOD/L containing fermentation media was diluted with a percentage of 130 of the initial working volume at the 3rd hour of the fermentation period. Moreover, this strategy enabled to start fermentation with 55 g glucose/L.

Effect of ammonium and COD concentrations on the performance of fixed-bed air-cathode microbial fuel cells treating reject water

In this study, a bio-electrochemical reactor comprising of anaerobic and aerobic chambers with filled granular activated carbon as biocarrier and third electrode was developed to investigate the effect of ammonium and COD concentrations on the power generation and COD removal. Two important operating parameters including initial COD concentrations (50–2000 mg/L) and initial ammonium concentrations (40–1000 mg/L) were optimized to attain the best response of electricity generation and COD removal using response surface methodology (RSM) through an experiments design software. A total of thirteen runs of experiments were employed for statistical analysis of data and developing empirical model, which has ability to predict optimum condition. Based on the results, the maximum COD removal efficiency was 96.8%, when the produced current at the maximum level was 1.149 mA. It was found that main variables as solely or combination effects significantly affect the efficiency of MFCs.

Integrated Treatment of Saline Oily Wastewater Using Sono-Electrokinetic Process, Degradation Mechanism, and Toxicity Assessment

Integration of sonication (US) with electrokinetic (EK) oxidation was studied for the treatment of a saline oily wastewater, as well as the effect of operating parameters, including pH, voltage, electrode distance (ED), sonication power, and reaction time on COD removal. A COD removal of 98 % was observed for the sono-electrokinetic (SEK) process with an applied voltage of 2.5 V, US power of 300 W, initial COD concentration of 3850 mg L–1, and reaction time of 9 h. The efficiency of SEK over sonication alone and EK oxidation alone was also confirmed with a higher pseudo-first-order reaction rate constant of 0.43 h–1, compared to values of 0.13 and 0.01 for alternative processes. In addition, the biodegradability of effluent was improved based on average oxidation state (AOS) and carbon oxidation state (COS) analysis. Oxygen consumption rate inhibition, dehydrogenase activity inhibition, and growth rate inhibition methods demonstrated the low toxicity of effluent (12–15 %) compared to influent. The current work indicated that SEK is a reliable and efficient technology for the treatment of saline oily wastewaters containing recalcitrant aromatic organics.

Sequential vertical flow trickling filter and horizontal flow multi-soil-layering reactor for treatment of decentralized domestic wastewater with sodium dodecyl benzene sulfonate

Sequential vertical flow trickling filter and horizontal flow multi-soil-layering bioreactor were investigated for the treatment of decentralized domestic wastewater at various concentrations of sodium dodecyl benzene sulfonate (SDBS). Results have shown that the removal rate of COD could reach 92.1% at initial COD concentration of 960 mg/L (800 mg/L was provided by SDBS). NH4+-N concentration could be reduced from 52.4 to 9.71 mg/L without aeration. Besides, a quadratic function model was fit to describe the relationship between the relative activity of amylase and the protein content in extracellular polymer substance. SDBS could inhibit the transport and metabolisms of amino acids, lipids and carbohydrates in biofilms. The analysis of three-dimensional fluorescence diagram indicated that the peak in excitation/emission wavelengths = 310–340/370–430 nm was the characteristic peaks of some active substances such as some enzymes in EPS. Only Microbacterium could totally offset the toxicity of SDBS degradation products.

Effects of initial concentration, adsorbent mass, pH and temperature to personal care products waste removal with activated carbon as adsorbent

Before being discharged into the water, waste from the personal care products (PCP) industry needs to be treated using the adsorption process. In this study, activated carbon is chosen as adsorbent because of its organophilic property, abundance, and continuous system. The experiment was carried out in batches using 3 variables of COD concentrations in PCP wastes in 250 ppm, 225 ppm, and 200 ppm with the adsorbent mass amount of 0.3 g/l, 0.35 g/l, and 0.4 g/l. In this experiment, the effects of initial COD concentration, adsorbent mass, pH, and temperature on the adsorption process, equilibrium models and mass transfer coefficients of adsorption will be analyzed. Equilibrium models of Distribution Coefficient, Freundlich, and Langmuir Model, were implemented in this experiment. From results of the study, the equilibrium system of PCP waste and activated carbon using Langmuir Equilibrium achieved a removal value of 69.03% at concentration of 200 ppm and the adsorbent mass of 0.4 g/l. To determine the mass transfer coefficient, an external adsorption model was used. The coefficient value of mass transfer coefficient (kc) with the trial method is 3.78x10-8 m/min. Using numerical method with MATLAB, the result is 7.6222x10-8 m/min, while using the analytical approach, the result is 7.413x10-8 m/min.