Permeable Reactive Barrier for Remediation of Acid Mine Drainage

By: Pimluck Kijjanapanich

I Introduction

O Objectives

S Scope of Study

L Literature Review

マスタ タイトルの書式設定M Methodology

マスタ タイトルの書式設定R1

Results and Discussion

C Conclusions

R2Recommendations

Contents

Acid Mine Drainage• the result of oxidation by air and water of metal

sulfides contained within mined rock as well as mine wastes.

• high acidity and high amounts of dissolved heavy metals such as Fe, Zn, Ni, Cu and Pb.

• extremely toxic to most organisms in both terrestrial and aquatic ecosystems.

HSOFeOHOFeS S 2227 2

42

222

OHFeHOFe 23

22 2141

HOHFeOHFe S 33 32

3

HSOFeOHFeFeS S 16215814 2

42

23

2

The oxidation of pyrite

Abandoned Gypsum mineSurat Thani Province

Abandoned Lignite coal mineLamphun Province

• The pH modification method - by using lime (CaO), limestone (CaCO3), sodium hydroxide (NaOH) or sodium carbonate (Na2CO3)

• Ion exchange

• Adsorption treatment

• Electrochemical treatment

• Membrane process

An interested approach to AMD treatment has been developed that imitate sulfate reduction phenomena occurred in the nature that carry out by sulfate reducing bacteria (SRB) and developed to use for AMD treatment.

The methods for treating AMD

Disadvantages of the conventional active treatment of AMD (Brown et al., 2002)

• Relatively high operation and equipment maintenance cost• The sludge is chemically complex, unstable, low density and gelatinous resulting

large volumes, making difficult and causes long-term problematic disposal

Biological Sulfate Reductionthe use of anaerobic sulfate reducing bacteria

(SRB), which can reduce sulfate to sulfide by oxidizing an organic carbon source.

OHCOSHHSOOCH 222242 22

HMSMSH S 22

2

Permeable Reactive Barrieran emplacement of reactive materials in the subsurface

designed to intercept a contaminant plume, provide a flow path through the reactive media and transform the contaminant(s) into environmentally acceptable forms to attain remediation concentration goals down-gradient of the barrier (Powell and Puls, 1997).

The two basic designs of PRBs

Funnel-and-gatePRB

Continuous PRB

•No need for expensive above-ground facilities for storage, treatment or transport, other than monitoring wells.

•After the installation the above-ground can be reused.

•There are no energy input and limited operational and maintenance costs.

•The in situ contaminant remediation is more effective than the simple migration control achieved by the impermeable barriers.

•Contaminants are not brought to the surface so that there is no potential cross media contamination.

•There no disposal requirements or disposal costs for treated wastes.

•Avoid the mixing of contaminated and uncontaminated water that occurs with pumping.

Advantages of Permeable Reactive Barrier(Powell and Puls, 1997; Puls et al., 1999)

To develop an appropriate PRB system for treating Acid mine drainage (AMD)

The specific objectives are:

• To select the appropriate organic material used as electron donors for treating AMD using PRB.

• To investigate the reaction rate through batch and continuous studies for evaluation of residence time in PRB

• To investigate the effect of pH and alkalinity on PRB performance.

• To investigate the performance of PRB in removing of heavy metal.

Objectives

Scope of Study• Five types of organic material were used including; 1) rice husk 4) septage2) coconut husk chip 5) composted pig manure3) bamboo chip• Sludge from Sanguan Wongse Industry wastewater treatment

was used as sulfate reducing bacteria (SRB) source.• Batch experiment is conducted in order to select reactive

materials and the appropriate residence time for treating AMD.

• Column experiment is conducted in order to investigate the effect of pH and alkalinity on PRB performance and heavy metal removal efficiency.

• The experiments is conducted in laboratory PRB model under anaerobic condition at ambient temperature.

• AMD from lignite coal mine will be used as a raw water.

Literature ReviewThe criteria for selection of electron donor• Reactivity• Stability• Availability and cost• Hydraulic performance• Environmental compatibility• Safety

Waybrant et al., 1995 the combination of more than one organic source is more successful than the use of solely one material.

Gibert et al., 2004 The lower the content of lignin in the organic substrates, the higher its degradability and capacity for developing bacterial activity and sheep manure was the most successful electron donor (sulfate removal level of > 99%)

Sulfate Reducing Bacteria (SRB)

• A group of anaerobic bacteria that can reduce sulfate to form sulfide.

• The genus Desulfovibrio is one of the most mentioned species in studies of SRB in natural water and wastewater.

• Gram negative, curved rods and usually having a single polar flagellum.

The specific environment requirement for SRB to enable sulfate reducing activity

(Gibert et al., 2002)

• Anaerobic environment (Eh around -200 mV)

• pH 5-8• The presence of electron donor

and appropriate sulfur species• A physical support

According to the study of Costa et al. (2007), no SRB activity was observed at pH 2. On the other hand, at pH 5 and 7 SRB growth was observed and this different pH (5 and 7) was not significantly to affect SRB growth.

METHODOLOGYLiterature Review

Selection of organic carbon sources

Laboratory Analysis

Data analysis and Discussion

Conclusion and Recommendation

Phase I: Batch Test

• Experiment set-up• Investigate appropriate

organic carbon sources and optimum residence time.

Phase II: Column Test

• PRB column design• Select the two of the best organic

carbon.• Investigate the effect of pH and

alkalinity and heavy metal removal efficiency.

Methodology: Batch Experiment

To investigate appropriate organic carbon sources and optimum residence time.

Five organic materials

Rice husk Coconut husk chip

Bamboo chip Municipal compost (septage)

Composted pig manure

BATCH EXPERIMENT

valves

gas releasing pipe

30 cm

7 cmOrganic Material 300 mL (20% by volume)

SRB source 100 mL (7% by volume)

AMD pH 6-7 1000 mL (66% by volume)

1.5 L

Reaction Bottle

BATCH EXPERIMENT

The criteria for making mixtureThe 3 types of single material were selected:

• the two of the single materials that have maximum sulfate reducing rate (composted pig manure, rice husk).

• the single material that has long lasting (coconut husk).

P R

C

Type of Organic Material

MixtureRice husk

Coconut husk chip

pig manure

Rice husk & Coconut husk (RC) 50:50 + + -Pig manure & Rice husk (PR) 50:50 + - +Pig manure & Coconut husk (PC) 50:50 - + +Pig manure, Rice husk & Coconut husk (PRC) 33:33:33 + + +

=> Mixed MaterialBATCH EXPERIMENT

RC PR PC PRC

Remark: + Have this type of organic material in the formula- No have this type of organic material in the formula

=> Batch

Parameters MethodsAlkalinity Titration Method

Oxidation-reduction potential (Eh) ORP meter

pH pH meterSulfate Turbidimetric Method

Volatile solid per total solid (VS/TS) Dried at 105 and 550 oC

ANALYTICAL METHODS

=> SamplingTwo of the reaction bottles were finished for analyzing at each sampling time.

Methodology: Continuous Experiment

To investigate the effect of pH and alkalinity and heavy metal removal efficiency.

Log phase

ktSOSO t 0

24

24 lnln

Estimation of the Reduction rate and Residence time

kk

S

S

HRT

t

100

10lnln

0

Slope = -k

Column Design

NaOH

30 mL/hr (0.155 cm/hr)

screen

gas releasing pipe

0.4 cm

Name A1 L1 A2 L2

Lime adding - + - +

Formula 1 1 2 2

ANALYTICAL METHODS

Parameters MethodsAlkalinity Titration Method

Dissolved Organic Carbon (DOC)

High-Temperature Combustion Method

Heavy Metal (Fe, Cu, Zn and Mn)

Inductively Coupled Plasma (ICP)

Oxidation-reduction potential (Eh) ORP meter

pH pH meterSulfate Turbidimetric Method

=> Continuous

Results: Batch Experiment part I

Characteristic of AMD from Banhong mine(Huttagosol and Kijjanapanich, 2008).

Parameters Value Standard* Standard**pH 4.20 - 5.0-9.0Acidity, mg/L CaCO3 91 - -

Total hardness, mg/L CaCO3 740 - -

Calcium, mg/L 260 - -Magnesium, mg/L 54 - -Sulfate, mg/L 623 - -Iron, mg/L 0.58 - -Manganese, mg/L 15.1 not excess 0.5 not excess 1.0Copper, mg/L 0.074 not excess 1.0 not excess 0.1Lead, mg/L 0.005 not excess 0.01 not excess 0.05Zinc, mg/L 1.80 not excess 5.0 not excess 1.0

* Groundwater Quality Standards of Thailand** Surface Water Quality Standards of Thailand

BATCH EXPERIMENT

BATCH EXPERIMENT

Type of organic materials Volatile solid/Total solid in 22 days (VS/TS)

rice husk Reduced from 0.788 to 0.763coconut husk chip Maintained at 0.957bamboo chip Maintained at 0.984municipal compost (septage) Reduced from 0.455 to 0.412composted pig manure Reduced from 0.625 to 0.594

Results: Batch Experiment IVolatile solid per Total solid (VS/TS)

Results: Batch Experiment I

=> pH

Alkalinity =>

Results: Batch Experiment I

=> Oxidation Reduction Potential (Eh)

Sulfate Removal =>

=> Color change in effluent Results: Batch Experiment I

Bamboo chip media Septage media Composted pig manure media

Coconut husk media Rice husk media Change of color in effluent of each organic material in 8 days

=> Color change in media Results: Batch Experiment I

composted pig manure media in 16 days

bamboo chip media in 16 days

Results: Batch Experiment part II

Results: Batch Experiment II

=> Alkalinity

Oxidation Reduction Potential (Eh) =>

Results: Batch Experiment II

=> Sulfate Reduction

84

9599

96

Sulfate Removal =>

Results: Continuous Experiment

Log phase

ktSOSO t 0

24

24 lnln

Using % Sulfate removal = 90%

From the calculation, HRT = 8.22-11.23 days

Safety factor = 1.5, HRT = 12.33-16.84 days

Reactor size = 15 L

kk

S

S

HRT

t

100

10lnln

0

Estimation of the Reduction rate and Residence time

Column Design

Name PRN PRL PRCN PRCL

Lime adding - + - +

=> Alkalinity

Results: Continuous Experiment

Oxidation Reduction Potential (Eh) =>

=> Sulfate Reduction

Results: Continuous Experiment

Sulfate Removal =>

=> Heavy metal RemovalResults: Continuous Experiment

Fe Cu

Zn Mn

Hydroxide Precipitation

=> Dissolved Organic Carbon (DOC)

Results: Continuous Experiment

Conclusion• Composted pig manure and rice husk had maximum sulfate

reducing rate and coconut husk had long lasting

• The suitable hydraulic retention time (HRT) was 16 days.

• The percentage of sulfate removal was up to 98%, which the residue sulfate concentration was 14.5 mg/L in PRL media.

• Effluent pH can be maintain in neutral range (6-8) and effluent alkalinity from composted pig manure was the highest.

• The concentrations of iron reduced from 23.34 mg/L to around 2 mg/L and copper & zinc concentrations could reach below groundwater quality standards of Thailand.

• The percentages of iron, copper, zinc, and manganese removal were 93 %, 99 %, 88%, and 96 % respectively in PRL reactor.

• The column reactors, which added lime into the media, had more efficiency than the reactor that no lime in the media.

Recommendation• Other type of organic materials should be tested. • The appropriate ratio of each type of organic material should be defined.• The lower pH of AMD should be tested on PRB system.• Other type of heavy metal and other concentrations of iron, copper, zinc, and manganese should be tested on PRB system.• Plug flow system reactor should be developed to solve the completely mixed problem.•AMD from different type of mine should be investigated on PRB system.• Performance of pilot should be further investigated.

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