Leachate Treatment at Virginia Landfills

By:

Bob Gardner, PE, BCEE

Senior Vice President

SWANA Old Dominion Conference

Wintergreen, VA

August 7, 2014

Leachate

• Leachate is defined as “liquid that has passed through or emerged from solid waste and may contain soluble, suspended or miscible materials”.

2

Treatment Goal

3

Undesirable

Acceptable

Acceptable

Undesirable

Unique Issues

• Variable quantity

4

5 Source: NASA

6

7

Leachate Generation

• Geographical/Climatic factors• Seasonal factors• Operational factors• Cover design

8

9

Unique Issues

• Variable quantity• Variable quality

10

Samples from Six VA LFs

11

Constituent Units Range

Type RawBOD5 mg/l 3.4-184COD mg/l 41-1300TOC mg/l 460

12

Constituent Units Range

Type RawBOD5 mg/l 3.4-184COD mg/l 41-1300TOC mg/l 460General

TSS mg/l 3.3-296Oil & Grease mg/lBromide mg/l 18Chloride mg/l 1200Fluoride mg/l 2Sulfate mg/l 120Alkalinity mg/l 3600Bicarbonate mg/l 3600Sulfide mg/l 22Sulfite mg/l 10Gross Alpha pCi/L 16.3Gross Beta pCi/L 462pH

13

Constituent Units Range

Metals mg/lArsenic mg/l 0.005-0.040Barium mg/l 0.147-3.86Cadmium mg/l 0.0002-0.524Chromium mg/l 0.0060-0.523Copper mg/l 0.011-0.048Iron mg/l 1.6Lead mg/l ND-0.530Nickel mg/l 0.0061-0.519Mercury mg/l 0.0025Sodium mg/l 1100Zinc mg/l .0152-0.213

14

Constituent Units Range

NitrogenAmmonia-N mg/l 2.3-1288Nitrate Nitrite mg/l 2TKN 171-1860

Phosphorous mg/l 4.8TCLP Pesticides ug/l .02012-1.11TCLPO ug/l ND

Unique Issues

• Variable quantity• Variable quality• Treatment & pretreatment constraints

15

9VAC25-31-770. National pretreatment standards:

prohibited discharges

• General prohibitions. A user may not introduce into any POTW any pollutant or pollutants which cause pass through, interference or violation of water quality standards.

16

Federal Requirements

17

• Title 40 of the Code of Federal Regulations, Parts 122, 123, 124, and 403, and chapter I, subchapter N.

• Subpart B of 40 CFR Part 445 “RCRA Subtitle D Non-Hazardous Waste Landfill Subcategory

Fundamental Issue

18

Conveyor with food

Fundamental Issue

19

Conveyor with food

Are there enough of us here to eat all

this?

Fundamental Issue

20

Conveyor with food

What’s the quality of the food?

Fundamental Issue

21

Will my Mom let me eat this?

Conveyor with food

Fundamental Issue

22

Can I or do I want to eat what’s on the plate passing by

me?

Conveyor with food

Treatment Requirements

• Varies by locality• Varies by time of day

– Hydraulic loading– Pollutant loading

• Varies by type of treatment plant• Varies by discharge limitations

23

24

Source: VDEQ for MSW LF’s Only

Unique Issues

• Variable quantity• Variable quality• Pretreatment constraints• Geographic constraints

– Rural– Urban

25

26

27

Key Components

• Raw leachate storage• Treatment (full or pretreatment)• Treated effluent storage• Discharge (onsite or to POTW)

28

29

60,000 GPD Onsite Leachate Storage, Treatment & Disposal Facility

Hillsborough County, Florida

750,000 gal. storage Treatment UnitNitrification/Denitrification

Office, equipment, and lab building

30

Leachate Hauling Fill StandHillsborough County, Florida

31

32

33

34

Leachate Storage and Pretreatment BasinsEscambia County, Florida

Typical Leachate Characteristics for MSW LFs

35

Constituent Concentration(mg/l)

pH 4.5 – 9

Alkalinity 300 – 11,500

Calcium 10 – 2,500

Magnesium 40 – 1,150

Chloride 100 – 5,000

Sodium 50 – 4,000

Sulfate 70 – 1,750

Ammonia Nitrogen 30 – 3,000

BOD5 20 – 40,000

COD 500 – 60,000

Source: Ehrig, 1989

Leachate Management Options

• Discharge to POTW – Pretreatment

– Direct, no pretreatment

• Onsite– Evapotranspiration

– Land application

– Recirculation

– Onsite leachate treatment36

Overview of Treatment Processes

• Biological treatment– Aerated lagoons– Activated sludge– Rotary contactors– Anaerobic digesters

• Chemical treatment– Precipitation/coagulation– Ion exchange

37

Overview of Treatment Processes (Cont.)

• Physical Treatment– Screening– Settling– Filtration

• Disinfection (Ultraviolet)• Membrane and Evaporation

Processes (e.g., Reverse Osmosis)

38

Key Points to Remember

• Highly strategies are site and facility specific.

• Treatability studies needed.• System must be robust.

39

Thank You!

Bob Gardner, PE, BCEE

Senior Vice President

SCS Engineers

Norfolk, VA

rgardner@scsengineers.com

40