Treatment Of Composting Leachate Research Articles

Simultaneous organic carbon, nitrogen removal, and electricity generation in a novel A4-MFC system for the treatment of leachate from a composting site: performance and modeling

A novel multi-chamber (A4) microbial fuel cell was utilized for the treatment of compost leachate with high organic matter and ammonium concentration.

Electrocoagulation Combined with Synthetic Zeolite—Does the Size of Zeolite Particles Matter?

Although electrocoagulation combined with zeolite (ECZ) shows higher efficiency in wastewater treatment, the actual contribution of zeolite particle size has not been fully explored. In this work, the influence of particle size of synthetic zeolite SZ (<90, 90–160, and 160–600 μm) on ECZ treatment of compost leachate with very high organic load is investigated together with different electrode materials (Fe, Al, and Zn), current densities (0.003, 0.009 and 0.018 A/cm2), and contact times (10, 20 and 30 min). The results positively highlight that the largest particle size should be used in ECZ, as it leads to a lower increase in pH and temperature, a higher decrease of chemical oxygen demand (COD) and turbidity, and a lower electrode consumption, while causing more damage to the electrode surface. The estimated energy costs ranged from 3.960 kW/m3–1313.657 kW/m3. The Taguchi L9 orthogonal configuration showed the highest COD and turbidity decrease under the conditions of 160–600 µm zeolite particles. The powder X-ray diffractometer (PXRD) analysis shows that interplanar spacing decreases when smaller and medium SZ particle sizes are used, while this effect was not observed with larger zeolite particle size. SEM-EDS shows that oxygen, silicon, and aluminium are the predominant elements in electrogenerated sludge coupled with zeolite.

Electrocoagulation treatment of compost leachate using aluminium alloy, carbon steel and zinc anode

Analysis of surface changes and corrosion occurrence at the electrode surface, electro-generated sludge analysis, and electrocoagulation (EC) treatment efficiency using aluminium alloy, low carbon steel, and zinc sacrificial anode as electrodes for the treatment of compost leachate with the medium organic load were compared for the first time. Different operating conditions (initial pH values in the range of 4–8, stirring rates in the range 70–270 rpm, and contact times in the range of 10–30 min) were used to study the EC process. Light microscopy analysis show the significant corrosion of anodes, while minor corrosion damage was also observed on the cathodes. Pitting was found on carbon steel and aluminium electrodes, and general corrosion on the zinc electrodes, which increase with the duration of EC (10 to 30 min). Weight loss analysis of electrodes shows a decrease in anode mass in all experiments and aluminium cathode mass, while steel cathode mass increases. Zinc cathode mass increases in initially acid and decreases in an alkaline environment. The highest anode consumption was obtained in the experiment with the Zn electrode (in the range of 0.3300–0.6469 g). SEM/EDS analysis of the electro-generated sludge confirmed the presence of aluminium, zinc, and iron, with oxygen as the main elements, while carbon indicated collected organic matter from the compost leachate. PXRD analysis of sludge shows a mixture of amorphous phase with the a semicrystalline phase of AlO(OH) and the crystalline phase of AlPO4 obtained with Al electrodes, an amorphous structure of the sludge obtained with Fe electrodes, and structurally well-ordered phases of Zn7Cu(OH)13((SiO(OH)3)0.7(O4H7)0.3(SO4)) and (Zn0.9Cu0.1)O obtained with Zn electrodes. In addition, the treatment efficiency was analysed and Taguchi's L9 orthogonal array design was performed.

Kinetic Study of Anaerobic Digestion of Compost Leachate from Organic Fraction of Municipal Solid Waste

The anaerobic digestion (AD) of compost leachate has been scarcely investigated and, to the best of our knowledge, no previous work has analyzed the kinetics of the process in completely stirred tank reactors (CSTR). To overcome this lack of knowledge, the present work aimed to deepen the study of the AD of compost leachate in CSTR and to identify the kinetics that can represent the process evolution under different operating conditions. In this regard, an experimental investigation was carried out on a laboratory anaerobic pilot plant that worked in semi-continuous mode under mesophilic conditions. After the start-up phase, the digester was fed with organic loading rates (OLR) between 4 and 30 gCOD/Ld. The chemical oxygen demand (COD) removal ranged between 80 and 85% for OLR values up to 20 gCOD/Ld and, then, it was observed as 54% at 30 gCOD/Ld. The deterioration of process performance was caused by an excessive generation of volatile fatty acids leading to a decrease of methane production yield from 0.32–0.36 LCH4/gCODremoved at 20 gCOD/Ld, to 0.23–0.26 LCH4/gCODremoved at 30 gCOD/Ld. Using kinetic analysis, the Monod model was shown to be quite accurate in modelling the trends of COD degradation rates for OLR values up to 20 gCOD/Ld. On the other hand, a better fit was achieved with the Haldane model at 30 gCOD/Ld. The conducted modelling allowed to identify the kinetic parameters for each model. The detected results could help in the management and design of the digesters for the treatment of compost leachate.

COMPARISON OF ELECTROCOAGULATION COUPLED WITH SYNTHETIC ZEOLITE, ULTRASOUND AND TWO STEPS ELECTROCOAGULATION

Due to the very complex composition of leachate wastewater, combining two or more physical, chemical, or biological processes, carried out simultaneously or sequentially, is highly needed in order to obtain effluent suitable for further discharge into sewage. In this paper, electrocoagulation coupled with synthetic zeolite (EC-NaX), electrocoagulation coupled with ultrasound (EC-US), and two steps electrocoagulation (EC-1st and EC-2nd) were tested for compost leachate treatment, with very high initial organic loading and acidic pH. The comparison of each process was done in regard to the following parameters: pH, electrical conductivity and temperature change, removal percentage of chemical oxygen demand (COD), turbidity, total solids change, settling ability, and electrode consumption. Results highlight the EC-NaX as the best option for the treatment of compost leachate, due to the highest removal percentage of COD (51.91%), satisfactory removal percentage of turbidity (97%), good settling abilities, and lowest electrode consumption. However, the final COD values in the effluent are still significantly high for further discharge into sewage systems, thus additional treatment needs to be applied. Also, the final acidic pH, high values of electrical conductivity, and high temperature of effluent need to be solved in further treatment steps.

Combining natural zeolite and electrocoagulation with different electrode materials – electrode surface analysis and Taguchi optimization

The treatment of compost leachate by the combined use of natural zeolite and electrocoagulation in a single step (ECZ) using different metallic materials of carbon steel, aluminium alloy, and zinc as electrodes was investigated. The experiments were divided into two parts. In the first part, the nine experiments were carried out in an electrochemical batch-type reactor under different operating conditions planned according to Taguchi's L9 orthogonal array design. The electrode material (Fe, Al, Zn), initial pH (4, 6 and 8), the addition of NaCl electrolyte (0.5, 1, and 1.5 g/L), and addition of zeolite (15, 20 and 25 g/L) were chosen as controllable factors, and their impact on chemical oxygen demand (COD) and turbidity were studied. The results show that the highest removal for both COD and turbidity was obtained with the Al electrode at pH 4 and an electrolyte addition of 0.5 g/L NaCl and 15 g/L of zeolite. However, the pH and the addition of zeolite do not have the same effect on COD and turbidity removal. Microscopic analysis of the electrode surfaces shows pitting, general or uniform corrosion, and coverage with a layer of corrosion products depending on the experimental conditions. The order of anode consumption was Zn > Fe > Al. Cathode consumption was evident in the experiments with the Al electrode, while both cathode consumption and increase in cathode mass was observed in experiments with the Fe and Zn electrode. In the second part, the influence of the initial COD concentration of the compost leachates treatment by ECZ with aluminium alloy electrodes was studied under optimal condition previously defined. Higher initial COD concentrations result in steeper curves of COD removal during ECZ and to a higher settling rate.

Integrated chemical coagulation with natural base coagulant – electro-proxone process and ultrafiltration membrane for treatment of compost leachate

Integrated chemical coagulation with natural base coagulant – electro-proxone process and ultrafiltration membrane for treatment of compost leachate

Simultaneous biodegradability enhancement and high-efficient nitrogen removal in an innovative single stage anaerobic/anoxic/aerobic hybrid airlift bioreactor (HALBR) for composting leachate treatment: Process modeling and optimization

A novel hybrid airlift bioreactor (HALBR) for simultaneous carbon and nitrogen removal from composting leachate was studied. In contrast to conventional airlift bioreactors, an anaerobic chamber was mounted at the bottom part to improve biodegradability of composting leachate and optimize overall COD removal. Desired aerobic and anoxic conditions provided by airlift configuration and oxygen concentration gradients within the biofilm increased the capability of system for TN removal through SND. Three independent variables, hydraulic retention time (HRT) (18–30 h), air flow rate (AFR) (1–2 Lair/min), and aerobic volume ratio (AVR) (0.22–0.26) were evaluated as operating parameters. The optimum conditions were an HRT of 28.3–30 h and AFR of 1.7–2 Lair/min, giving 3600 mg/L (90%) of COD and 598.4 mg/L (80%) of TN removal, respectively with an effluent turbidity less than 70 NTU. The outcomes demonstrated that this innovative single HALBR is a feasible and reliable technology for treatment of composting leachate.

Zeolite-intermittent cycle moving bed air-lift bioreactor (Zeo-ICMBABR) for composting leachate treatment; simultaneous COD, nitrogen and phosphorous compounds removal.

Anaerobically pretreated composting leachate contains high ammonia load and soluble organic matter, which requires further treatment. In this study, simultaneous removal of COD, nitrogen, and phosphorus compounds from anaerobically pretreated composting leachate investigated by using an intermittent cycle moving bed airlift bioreactor (ICMBABR) supported by zeolite as a biofilm. The efficiency of COD, Total Kjeldahl Nitrogen (TKN), and phosphorous removal and contaminants profile during the process, and the mass balances were analyzed. A multilayer design used for the experimental design, and the effect of four variables including hydraulic retention times (4, 6, 8h), the zeolite ratios (20, 35, 50%), the influent COD concentration (1, 2, and 3g/L) and aeration duration (64, 73, and 82%) investigated by Response Surface Methodology (RSM). According to the results and process profile the sequence of anoxic and aerobic conditions, presence of the anaerobic zone in the bottom of the reactor, as well as the use of zeolite as adsorbent media, significantly allowed the simultaneous removal of COD (99%), TKN (95%), and total phosphorus compounds (90%) from anaerobically pretreated composting leachate and favorable potential to remove nitrogen compounds by high efficiency (79%) through simultaneous nitrification and denitrification (SND).

Kinetic Analysis and Treatment of Compost Leachate Using Data from a Plant-Scale Hybrid Anaerobic Reactor

AbstractCompost leachate is one of the most strongly polluting wastewaters, which is found in significantly large amounts. The major objective of this research was to study the biological treatment...

An experimental study on the influence of zeolite on changes of pH and alkalinity in anaerobic treatment of compost leachate

AbstractWith the increase of urbanization, municipal solid waste has also increased. Therefore, the need for solid waste management is also increasing compared with earlier decades. Composting is a good option for the recycling of solid waste; however, it produces leachate, which requires proper treatment systems to prevent environmental degradation. Due to high chemical oxygen demand (COD) concentrations in compost leachate, anaerobic treatment is the best option for handling the effluent, and an anaerobic baffled reactor (ABR) is one such anaerobic reactor that can be used for its treatment. Because of high ammonia and heavy metal concentrations, as well as the possibility of sludge washout in ABRs, it is important to use proper media, such as zeolite, which can reduce inhibition effects and sludge washout from the reactor. Anaerobic treatment, especially during the methanogenesis phase, is sensitive, and pH and alkalinity are parameters that influence the treatment. Therefore, adjusting these parameters within a normal range is very important to the proper functioning of anaerobic systems. In this study, a pilot‐scale ABR was used, and the last 4 of the 8 ABR compartments were filled with zeolite. The bioreactor was operated at hydraulic retention times (HRT) of 3, 4, and 5 days, with zeolite filling ratios of 10%, 20%, and 30%, and influent COD concentrations of 10,000, 20,000, and 30,000 milligrams per liter (mg/L). In this study, pH value was 6.43 ± 0.1, 6.96 ± 0.3, and 6.96 ± 0.25 at filling ratios of 10%, 20%, and 30%, respectively. According to the results, in all filling ratios, no significant changes were observed in the pH value when the organic loading rate increased and its amount was within a constant range. Influent alkalinity was equal to 2015 ± 510, 2884 ± 505, and 4154 ± 233 milligrams of calcium carbonate per liter (mg CaCO3/L) at influent COD concentrations of 10,000, 20,000, and 30,000 mg/L, respectively, and in effluent, they were 2536 ± 336, 3379 ± 639, and 4377 ± 325 mg CaCO3/L, respectively. The amount of alkalinity in the effluent increased compared with the alkalinity in the influent. The results show that the amount of alkalinity in the influent and effluent was similar, and the alkalinity enhancement was lower when the filling ratio was increased from 10% to 20%, and 20% to 30%. Comparisons of the results from zeolite with and without biofilm showed that, in cases of zeolite with biofilm, the amounts of silica and oxygen decreased and the amount of carbon increased, and it showed the formation of biofilm on the surface of zeolite. In addition, the absence of sodium in the zeolite with the biofilm indicated that sodium was exchanged with ammonium ions. According to the results, zeolite can be used in anaerobic reactors as a medium, and it also reduces fluctuations in pH and alkalinity at different organic loading rates, providing a normal range for anaerobic treatment.

Enhanced Composting Leachate Treatment Using Extracellular Polymeric Substances as Bioflocculant

AbstractThis study investigates the use of extracellular polymeric substance (EPS), an eco-friendly and biodegradable bioflocculant, for the treatment of composting leachate [raw leachate (BR9) and...

Coagulation/Fenton oxidation combined treatment of compost leachate using quince seed mucilage as an effective biocoagulant

ABSTRACT In this study, quince seed mucilage (QSM) has been introduced as a novel biocoagulant for the pretreatment of leachate obtained from a composting facility. Response surface methodology (RSM) was used to study and optimize the effect of pH, QSM dosage and time on the coagulation performance. At the optimum conditions using 1370 mg L−1 of QSM at pH 3.8 and 29 min, 45.0% COD reduction was achieved in the coagulation-flocculation (CF) stage. After CF pretreatment stage, Fenton oxidation (FO) process was applied on the leachate. Maximum COD reduction was obtained at pH 2.5, H2O2 concentration of 190 mM, and Fe2+ concentration of 1.64 mM. At the optimum conditions of the combined treatment process, up to 84.4% COD, 99.4% turbidity and 98.2% BOD were removed. The combined CF/FO process using QSM in the CF stage was found to be an effective method for the treatment of compost leachate.

Treatment of compost leachate by ferro-sonication process: Effect of some operational variables

Aim: Application of composting process for the management of organic solid waste led to the production of leachate, which causes many problems to environment. This study was aimed at investigation of ferro-sonication (FS) process in composting leachate degradation. Materials and Methods: Leachate samples were collected in composting factory located in Isfahan. In each run, 400 ml of leachate was sonicationed through an ultrasonic homogenizer in a cylindrical glass reactor. Ferrous sulfate was added to the reactor as accelerator agent. The effect of various parameters including pH, ferrous sulfate doses, sonication times, and ultrasonic intensity was studied in the removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) from composting leachate. Results: The results showed that the COD and BOD removal rate was increased by increasing ferrous sulfate dosages, sonication time, and ultrasonic intensity. In addition, lower pH was favored for leachate degradation. In general, the optimum conditions for pH, ferrous sulfate dosage, irradiation time, and ultrasonic intensity were 3, 8 mmol, 180 min, and 150 W, respectively. Approximately 46% of COD and 33% of BOD were removed in optimum condition. Conclusion: These results revealed that FS can be effective in degradation of compost leachate and can be presented as a good choice for pretreatment of leachate.

Complete Treatment of Compost Leachate Using Integrated Biological and Membrane Filtration Processes

A lab-scale SBR equipped with a flat sheet membrane in submerged configuration that is named MSBR was used for the treatment of composting leachate. It was fed by biologically treated leachate with overall 70-1360 mg/L Chemical Oxygen Demand (COD). The values of pH, Electrical Conductivity (EC), and Dissolved Oxygen (DO) were monitored routinely. However, analysis of total COD, Soluble COD (SCOD), Biological Oxygen Demand (BOD5), Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) was done in feed and filtrate, whenever the system reached steady state twice a week for about 6 months.In all loading rate, BOD5 concentration was less than standard limit. The removal efficiency of total COD increased in the bioreactor with time in all experiments was up to 80%.Influent SCOD varied spectacularly (50-1050mg/L) due to the leachate collection during different seasons but in the effluent, it remained relatively stable. About 60% of the feed SCOD was the non biodegradable type that was separated by the membrane.Up to 99 % further solids was removed with micropore membrane which might be mainly included in colloidal solids. The value of EC for the leachate sample was 0.86-4 mS/cm at 22 °C which decreased by membrane significantly.It was concluded that MSBR as a versatile technology with high throughput could treat composting leachate belowthe standard limit if used after proper processes.

Treatment of compost leachate by the combination of coagulation and membrane process

This study describes the treatment of composting leachate by the combination of coagulation and nanofiltration process. Poly ferric sulfate (PSF) was used as coagulant, and the effect of pH value and PSF dosage on the coagulation performance was investigated. The results indicated that the chemical oxidation demand (COD) and turbidity removal efficiency could reach to 62.8% and 75.3%, respectively at an optimum dosage of 1200mg·L−1 at pH6.0. During the nanofiltration process, the operation conditions such as temperature and pressure were optimized, 89.7% of COD, 78.2% of TOC, 72.5% of TN, 83.2% of TP, and 78.6% of NH3-N were retained when tested at 0.6MPa at 25°C. The final leachate effluent concentration of COD, BOD5, NH3-N, TOC, SS was 92mg·L−1, 31mg·L−1, 21mg·L−1, 73mg·L−1 and 23mg·L−1, respectively, which reached the local discharge standard. The combination of coagulation-filtration is useful for composting leachate treatment.

Optimization of photocatalytic post-treatment of composting leachate using UV/TiO2

In this study, optimization of photocatalytic process via UV light and TiO2 nanoparticles immobilized on concrete surface in post-treatment of composting leachate was investigated. This investigation was conducted in laboratory scale and batch mode. Biological pretreated leachate samples were collected from the effluent of Gorgan composting leachate treatment facility in the north of Iran. Optimization of the simultaneous COD and color removal were carried out through experiments designed by response surface method and central composite design with six replications in central point. Based on the results of experiments, after 21.5 h of radiation with 7.5 mW Cm−2 light intensity in pH 5.7 and in the presence of 48.8g m−2 immobilized TiO2, maximum simultaneous COD and color removal were achieved to be 58 and 36%, respectively. GC/MS analysis revealed that the composting leachate contained various groups of refractory organic compounds, most of which could be degraded into simpler and more biodegradable by products, using photocatalytic process.

Membrane bioreactor technology: A novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography – mass spectrometry (GC/MS) and inductively coupled plasma – mass spectrometry (ICP–MS) respectively. A decrease of more than 99% was achieved for a COD of 116g/L in the initial leachate. Ammonia was decreased from 2720mg/L to 0.046mg/L, while the nitrate concentration in the effluent rose to 710mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.

Aerobic composting leachate treatment by the combination of membrane processes

The main product of the conversion process of organic wastes to a useful organic fertilizer, known as compost, has gained an increasing interest in management of organic wastes recently. One of the main problems arising in the composting facilities is the high organic loaded leachate. In this study, a treatability experiment for composting leachate from a full-scale composting facility was carried out with the combination of membrane processes. The parameters such as chemical oxygen demand, total organic carbon, Cl⁻ and NH₄⁺ were analysed to evaluate the membrane treatment performances of single and combined membrane systems consisting centrifuge, cartridge filter, ultrafiltration and nanofiltration membranes. The removal efficiencies of all pollutants were observed between 4.4 and 98%. The highest removal efficiencies were observed with the nanofiltration membrane (NF90) having a lower molecular weight cut-off than the others used in this study. It was observed that the effluent of NF90 membrane did not exceed the allowed maximum COD value.