Summary: INVESTIGATION OF ELECTROCHEMICAL OXIDATION FOR TREATMENT OF LANDFILL LEACHATE Daniel E. Meeroff (PI) 1 Md Fahim Salek

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1 Summary: INVESTIGATION OF ELECTROCHEMICAL OXIDATION FOR TREATMENT OF LANDFILL LEACHATE Daniel E. Meeroff (PI) 1 Md Fahim Salek In 217, the Bill Hinkley Center for Solid and Hazardous Waste Management funded FAU Lab.EES to investigate the efficiency of a prototype of an electrochemical oxidation reactor to remove selected parameters of interest (such as COD/BOD, ammonia, heavy metals, color, turbidity) from landfill leachate for safe discharge or reuse of the treated leachate. The project will also explore the generation of byproducts (i.e. trihalomethanes, Haloacetic acids, chlorine gas, etc.) during treatment. Landfill leachate is a liquid that drains from landfill and usually contains dissolved and suspended solids. Because of its high amount of recalcitrant organic material, color, ammonia, chlorides, and heavy metals such as arsenic, lead, and iron, it has become a significant threat to groundwater and surface water sources. It is also challenging to treat because of its variable composition depending on its age and the type of waste dumped in the landfill. According to a study by Dr. Daniel Meeroff and Dr. Teegavarapu in 21, the amount of leachate produced from Class 1 landfill can be up to 7 gallons per acre of landfill. This volume of leachate is either managed by deep-well injection, onsite treatment or by sewer discharge. Many technologies have been proposed to treat landfill leachate and some including energized processes such as photocatalytic oxidation with titanium dioxide have been explored at FAU Lab.EES. Electrochemical oxidation method has emerged as a promising method for removal of pollutants typically found in leachate. In the last couple of years, it has been successfully used for treating wastewater from tannery, power plants, municipal areas, and landfills, and recent progress in development of next generation electrochemical oxidation technologies, particularly in China has led FAU Lab.EES to partner with two equipment manufacturers to test the latest prototypes. The objective of the research is to investigate different pretreatment processes of landfill leachate along with electrochemical oxidation. Initially, a low-cost Advanced Oxidation Reactor preceding a Magneli Electrochemical Reactor will be tested. Subsequently, other pretreatments such as ozonation and Fenton application will be analyzed. The efficiency of the processes will be determined based on the removal of COD, ammonia, turbidity, and color, and other indicators, as necessary. Electrochemical oxidation of landfill leachate may produce harmful byproducts in the presence of organics and chloride in leachate. Therefore, byproduct generation will be analyzed to determine if post-treatment is required. 1 Prof. and Assoc. Chair, Dept. of Civil, Environmental & Geomatics Engineering, Florida Atlantic University, 777 Glades Road, 36/26, Boca Raton, FL , Phone: (561) , dmeeroff@fau.edu 1

2 PROGRESS REPORT (March 218) Project Title: INVESTIGATION OF ELECTROCHEMICAL OXIDATION FOR TREATMENT OF LANDFILL LEACHATE Principal Investigators: Daniel E. Meeroff, Ph.D. Affiliation: FAU Phone number: (561) Project website: Student: Md Fahim Salek Methodology/Scientific Approach TASK 1. Conduct Literature Review: Md Fahim Salek has conducted a preliminary literature review to determine: 1) Major constituents of leachate, 2) Different methods for leachate treatment and expected efficiency, 3) Kinetics of electrochemical oxidation, and 4) Factors affecting electrochemical oxidation of landfill leachate. The team is still continuing the literature review for process modification for increasing the performance efficiency and collecting cost information. TASK 2. Perform laboratory scale experiments. In partnership with the Solid Waste Authority (SWA) of Palm Beach County, FAU Lab.EES has collected leachate samples for testing various parameters, specifically ammonia and COD. OriginClear and Magneli Materials has provided two laboratory scale units (4-6 liter capacity) for preliminary testing. Initial testing has been done to observe the removal efficiency of COD and ammonia from collected samples. Figure 1: Advanced Oxidation Reactor from OriginClear Figure 2: Magneli Reactor TASK 3. Assess treatment performance. During the experiments, FAU Lab.EES has monitored COD, ammonia, turbidity, color, and chlorides to evaluate and optimize system performance. Additional parameters monitored as a part of the process include: energy consumption in the form of amperage and voltage, ph/temperature, and conductivity. The team has tested artificial leachates containing KHP (as a COD surrogate) with three chloride levels (28 mg/l, 5 mg/l and 19 mg/l) to determine the optimum chloride content for better performance. 2

3 COD (mg/l) O2 COD (mg/l) O2 COD at 5 mg/l Cl Conc. COD at 28 mg/l Cl Conc. COD at 19 mg/l Cl Conc TIME (MIN) Figure 2: COD Removal of Advanced Oxidation Reactor COD at 5 mg/l Cl Conc. COD at 28 mg/l Cl Conc. COD at 19 mg/l Cl Conc TIME (MIN) Figure 1: COD Removal of Magneli Reactor TASK 4. Assess byproduct generation. Treating landfill leachate can produce halogenated byproducts like THMs, HAA5s, chlorine gas, etc. due to the presence of organics and chlorides in leachate. Future adoption of electrochemical treatment requires minimization of undesired side reactions that reduce treatment efficiency and form potentially toxic byproducts. An important step will be to determine if halogenated byproducts are generated. TASK 5. Develop final recommendations and preliminary cost analysis. Using the data collected from Tasks 2 to 4, the appropriate reactor conditions needed to meet discharge water quality guidelines will be determined. A preliminary operating cost will be determined in terms of electricity consumption, operation and maintenance in dollars per gallon treated. The first TAG meeting was held on February 9,

4 Florida Atlantic University College of Engineering & Computer Science Landfill Leachate Treatment by Advanced Electrochemical Oxidation Md Fahim Salek Advisor: Dr. Daniel Meeroff February 9, 218 Introduction Electrochemical oxidation (EOx) involves direct oxidation of pollutants at the anode as well as indirect oxidation by hydroxyl radical, chlorine, hypochlorite ion, and other secondary oxidants EOx seems promising for removal of COD, ammonia, and other contaminants from leachate Recently, EOx has been successfully used for treating wastewater from tanneries, power plants, and landfills February 9, 218 1

5 Objectives 1. Conduct testing to determine the efficiency of EOx to remove selected parameters of interest (such as COD/BOD, ammonia, heavy metals, color, turbidity) for safe discharge or reuse of treated leachate 2. Determine if halogenated byproducts are generated during the process February 9, 218 Methodology 1. Perform laboratory scale experiments to assess treatment performance of a 2 stage EOx unit 2. Assess byproduct generation 3. Develop final recommendations and preliminary costs February 9, 218 2

6 Task 1: Collect data on electrochemical oxidation Anode Material Current Density (Am 2 ) Volume of Sample (L) Time (h) COD Removal % Ammonia Removal % Cl mg/l Authors Ti/RuO2 IrO2 26 A m H. Zhang et. Al (211) 8 A m Ti/IrO2 RuO2 16 A m 2 4 N/A 615 E. Turro et. Al (211) 32 A m A m Ti/RuO2 IrO2 9 A m 2.8 N/A H. Zhang et. Al (211) Graphite carbon 8 A m N/A N/A M. Bashir et. Al (9) BDD 2571 A m A. Anglada et. Al (211) Ti/Pt A m F. Feki et. Al February 9, 218 Experimental Set up EWS:AOx Reactor Magneli Membrane Reactor February 9, 218 3

7 Test Details Batch Reactor Flow Reactor Ampere Range Amps Ampere Range Amps Voltage Range 5 & 7 Volts Voltage Range 4.7 & 6 Volts Electrooxidation Time 75 9 mins Electrooxidation Time 75 mins Anode Material Sample Volume Titanium connected using steel nuts and bolts 4 liters Anode Material Flow Sample Volume Titanium coated with IrOx and RuOx 4 liters/min 4 liters February 9, 218 COD Removal Results Ammonia Removal BATCH REACTOR FLOW REACTOR BATCH REACTOR FLOW REACTOR BATCH REACTOR FLOW REACTOR BATCH REACTOR FLOW REACTOR Initial Ammonia Final Ammonia Initial COD Final COD Sample Source Removal Efficiency COD Removal Monarch Hill 52% SWA 83% Ammonia Removal Monarch Hill 28% SWA 4% February 9, 218 4

8 Turbidity in NTU Turbidity Elapsed Time (min) EWS:AOx Reactor Results Turbidity ElapsemTime (min) Magneli Membrane Reactor Turbidity in NTU Sample source: Monarch Hill February 9, 218 Results Turbidity in NTU Turbidity Turbidity in NTU Turbidity Elapsed Time (min) Elapsed Time (min) Sample source: SWA EWS:AOx Reactor Magneli Membrane Reactor February 9, 218 5

9 Results The low removal of COD and ammonia might be because of low initial chlorine concentration [1] [2] Humic acids may also interfere the treatment process by adsorbing hydroxyl radical. [3] Humics also acts as photon traps. Zepp at al. stated phenolic group of humic are responsible for this efficiency reduction Turbidity and color increase during the oxidation process is quite unusual while COD and Ammonia were decreasing. This might have come from the iron bolts used during the experiment [1] Chiang, L.C., Chang, J.E. and Chung, C.T., 1. Electrochemical oxidation combined with physical chemical pretreatment processes for the treatment of refractory landfill leachate. [2] Li, L. and Liu, Y., 9. Ammonia removal in electrochemical oxidation: mechanism and pseudo kinetics. [3] Konstantinou I.K., Zarkadis A.K., Albanis T.A. and Triantafyllos A. (1). Photodegradation of selected herbicides in various natural waters and soils under environmental conditions. J. Environ. Qual. 3, February 9, 218 Task 2: Perform laboratory scale experiments A synthetic COD solution was prepared by adding KHP, NaCl and NaHCO 3 to deionized water to assess COD removal efficiency The prepared solution was treated in an open electrochemical oxidation chamber for 1 hour After that, the solution went through a closed electrochemical oxidation chamber for 1 hour February 9, 218 6

10 Task 3: Assess treatment performance COD (MG/L O2) COD at 5 mg/l Cl Conc. COD at 28 mg/l Cl Conc TIME (MIN) EWS:AOx Reactor COD (MG/L O2) COD at 5 mg/l Cl Conc. COD at 28 mg/l Cl Conc TIME (MIN) Magneli Membrane Reactor February 9, 218 Task 3: Assess treatment performance Chloride Conc. Reactor Removal Efficiency Removal Rate 5 mg/l Cl 28 mg/l Cl Batch Reactor 6.3% 2.3 mg/l min Flow Reactor 18.4%.26 mg/l min Batch Reactor 5% 1.86 mg/l min Flow Reactor 25.8%.44 mg/l min February 9, 218 7

11 Task 3: Assess treatment performance Turbidity at 5 mg/l Cl Conc. Turbidity at 5 mg/l Cl Conc. Turbidity at 28 mg/l Cl Conc. Turbidity at 28 mg/l Cl Conc. 3 6 TURBIDITY (NTU) TURBIDITY (NTU) TIME (MIN) TIME (MIN) EWS:AOx Reactor Magneli Membrane Reactor February 9, 218 Task 4: Assess byproduct generation 1. Treating landfill leachate can produce halogenated byproducts like THMs as high as 2, ppb, higher than the EPA s MCL [1] 2. Depending on ph and anode material, the oxidation mechanism follows 2 routes: Electrochemical conversion or electrochemical combustion. By maintaining ph > 7, combustion can be favored, which will generate less halogenated byproducts [2] 3. Later on, generated gas can be trapped and analyzed using GC/MS [1] Li, Nanzhu & Deng, Yang. (212). Formation of Trihalomethanes (THMs) during Chlorination of Landfill Leachate. International Journal of Environmental Pollution and Remediation /ijepr [2] A. Anglada, A. Urtiaga, I. Ortiz, Contributions of electrochemical oxidation to wastewater treatment: fundamentals and review of applications, Journal of Chemical Technology and Biotechnology 84 (9) February 9, 218 8

12 Next Steps 1. To determine the optimum chlorine concentration that maximizes removal rate 2. To evaluate ozonation or Fenton as pretreatment 3. To monitor production of halogenated byproducts, such as THMs and HAA5 4. To perform a preliminary cost analysis and comparison with other existing methods February 9, 218 Discussion 1. What is the optimum ph range for getting higher efficiency? 2. How much flow is required in the flow chamber? 3. What is the recirculation rate? February 9, 218 9