REDUCTION OF THE AMMONIACAL-N CONCENTRATION OF THE LANDFILL LEACHATE BY OVERLAND FLOW SYSTEM

Silsoe College

Department of Agricultural Water Management

MSc. Part II Environmental Water Management

1994-1995

REDUCTION OF THE AMMONIACAL-N CONCENTRATION OF THE LANDFILL LEACHATE BY OVERLAND FLOW SYSTEM

ON CLAY AND SANDY LOAM SOILS

CRISTOBAL PINCHE - LAURRE

Supervisor: Sean Tyrrel

This paper is submitted in partial fulfilment of the requirements for the degree of Master of Science

ACKNOWLEDGEMENTS

I would like to thank Silsoe College, especially Sean Tyrrel for his guidance and his suggestions to complete this research project, and Simon Medaney for his support in the edition of this thesis.

My especial gratitude to my wife Loren Ruiz Garcia who supported my MSc. studies and help me with this project.

Finally, I also thank the British Council for granting me with a scholarship to get my MSc. degree at Silsoe College.

REDUCTION OF THE AMMONIACAL-N CONCENTRATION OF THE LANDFILL LEACHATE BY OVERLAND FLOW SYSTEM

ON CLAY AND SANDY LOAM SOILS

Cristobal Pinche-Laurre, MSc Environmental Water Management,

Silsoe College, 1995

_____________________________________________________________________

ABSTRACT

Landfill leachate had been researched previously to achieve permissible level of contaminants. This study focuses in ammonium removal by overland flow system in the clay and the sandy loam soils. This was carried out by daily recirculation of leachate on a pilot-scale overland flow. The result showed good performance (70.65% in Sandy Loam and 94.94% in Clay soils) in mass ammonium removal, and reduction of leachate volume in the clay soil. There was no effect of the soil type during the first 5 days of experiment. After that, ammonium removal in the clay soil was higher than in the sandy loam soil. Nitrate production was not significantly different between the two soil types. The research shows that the CEC is an important factor in ammonium removal.

TABLE OF CONTENTS

1. INTRODUCTION....................................................................................... 2

1.1. Landfill leachate treated by Overland flow.................................................... 3

1.2. Ammonium removal processes in Landfill leachate treatment......................... 7

1.3. Overland Flow treatment on ammonium removal.......................................... 9

1.4. Soil Type and Ammonium removal..............................................................10

2. AIM AND OBJECTIVE..............................................................................14

3. MATERIALS AND METHODOLOGY......................................................15

3.1. Leachate characteristics................................................................................15

3.2. Grass Plots...................................................................................................15

3.3. Operation of the overland flow plot...............................................................16

3.4. Determination of ammonium and nitrate........................................................17

4. RESULTS.....................................................................................................18

4.1. Ammonium removal by overland flow system in Sandy loam

and Clay soils...............................................................................................18

4.2. Nitrate Concentration and Total Mass in Sandy loam and Clay soils.................22

4.3. Grass condition and Volume reduction of leachate during

overland flow treatment.................................................................................25

5. DISCUSSION................................................................................................26

5.1. Ammonium removal......................................................................................26

5.2. Nitrate reduction............................................................................................26

5.3. Permeability effect.........................................................................................27

6. CONCLUSIONS............................................................................................28

7. REFERENCES..............................................................................................29

1. INTRODUCTION

Landfill represents more than 65 % of the waste disposal in UK. It has increased in the last 20 years, because it is the cheapest way to dispose of more than 90 % of domestic waste and over 80 % of hazardous waste (Croner Publication, 1995).

Landfill gas and leachate are the main landfill residues which can endanger the environment. Landfill gas is mainly composed of methane and carbon dioxide. They are generated by the microbiological processes known as anaerobic digestion in which organic matter is degraded in the absence of oxygen (Hooker, 1993). Landfill gas can be managed by landfill gas control.

Leachate is formed by the action of water (precipitation) passing through a landfill, becoming contaminated with various organic and inorganic pollutants produced by the biodegradation of waste material (Crawford and Smith 1985). Leachate (Table 1), due to its high concentration of ammoniacal-N, requires efficient management techniques to prevent the contamination of surface fresh water and groundwater .

Leachate can be treated by off-site treatment and disposal or by on-site treatment. The former refers to a transfer of leachate to sewage works. The latter refers to a low technology treatment system (Crawford and Smith 1985).

A common and effective mean of leachate treatment is land treatment, specifically overland flow. This relies on processes in the soil-plant system to reduce the high level of ammoniacal-N.

Table 1. Typical composition of leachate from recent and aged domestic waste

(All results in mg/l except pH value)

PARAMETER AGE OF REFUSE

< 2 years old > 10 years old

pH 5-6.5 6.5-7.5

BOD 4000-30000 < 100

COD 10000-60000 50-500

TOC 1000-20000 < 100

Total solids 8000-50000 1000-3000

TSS 200-2000 100-500

N (NH3-N or Org-N) 100-1000 < 100

Phosphate 5-100 <

...