Bio-remediation for Selenium

Making it Work for Agriculture

THE PROBLEM

Selenium is being added to natural waterways in areas where agriculture provides return water after irrigation

Selenium at the concentrations reported in certain waterways has been determined to be harmful to waterfowl, fish, and potentially to humans

Federal authorities may assign irrigators some responsibility for reducing the selenium concentrations in the return water.

Bio-accumulation

Water

Algae

Insects

Fish

Birds

1

10

100

1,000

10,000

The Regional Problem The total load of selenium entering the Colorado

River from three reaches of the Umcompahgre and Gunnison Rivers creates concentrations that have been determined to be environmentally toxic

Agriculture may be required to share the responsibility for reducing the Se load

Agriculture in the region depends upon irrigation and drainage

Any solution for Se discharges from farms will need to be farm friendly and agriculturally compatible

If agriculture is required to participate in reducing selenium,

how should we develop a solution?

Localize the problem Review the literature Consolidate the available information Develop a model remediation program

that addresses the site-specific need

AGRARIAN’S DESIGN PROCESSDATA REVIEW

UNDERSTANDING THE PROBLEMPOLITICALECONOMICECOLOGICAL

INITIAL CONCEPTTHOUGHT EXPERIMENTS METHODS TECHNOLOGIES INFRASTRUCTURE

DESIGN

DEMONSTRATION PROJECTPROOF OF CONCEPT

EMPIRICAL EVALUATION

ACCEPT ELIMINATE MODIFY EXPAND

SCIENTIFIC INQUIRY ON PROCESS

RECOMMENDED ACTIONS

What the Science Says

Selenium is a trace metal, and can be removed in a desalinization plant

Se can change forms, and some forms are more soluble and/or more toxic than others

Se can be taken up in some quantity by certain plants under certain conditions

Selenium can be volatilized under certain conditions Certain biological processes produce insoluble forms of

selenium, which are removed from the water. Insoluble forms of Se remain in sediment and are

generally less bio-available

Project Development for Selenium Removal in

California’s Central Valley:Broadview Water District

Characteristics of the project:•10,000 acre irrigation and drainage district •seleniferous soils in the west side of the San Joaquin Valley•active network of open and tile drains•regulatory pressure for reduction of selenium in discharged drain water•project funding from federal (BOR) source, including in-kind cost sharing

Agrarian’s Goals for Broadview Reduce the Se load leaving Broadview: current

annual load target is 852 lbs. Focus on “hot spots”, i.e. the few sumps that

produce most of the selenium Minimize impacts to wildlife by restricting

access to the project Minimize long-term costs Develop a project that is compatible with the

agricultural setting

Important Concepts Utilized Selenium volatilization can take place in wetland

settings Selenium reduction can also take place if the

environment is low in oxygen The volatilization and the reduction take place in

the plant roots, probably via bacteria that live in the root environment

Optimal bacterial action will take place if the bacteria are well fed AND in maximum contact with the selenium in the water

A Flow-through Wetland

Water flows through the hay bale with the plants,contacting the root mass with the bacteria on them.

Selenium transformation takes place in the roots.This is a true flow-through wetland.

The water on our project must flow THROUGH the root mass on the plants in the straw bales

Channel pattern for Se removal project

280 feet Treatment 1

Treatment 2T

reatment 3

Intake

Discharge

Discharge

Discharge

Intake

Intake12345

7

mid-point

mid-point

mid-point

meter

meter meter

meter

meter

FIGURE 1. Schematic of selenium reduction channel project at Broadview Water District

535 feet

meter 6

Intake

Discharge

There are 11 channels in a treatment, and theyform a block that is a total of 3300 feet long. Water moves from the intake to the discharge,through the meanders, with a residency time of 21-50 days, depending on the season.

Channels used in Broadview Project

15.5 '

8.5 '3.5 '

2.5 '

14 " 18 "1

~ 1.6

average water line

Schematic in cross section of the dimensions of the channels used in the selenium reduction project at Broadview Water District.

Broadview’s Selenium Treatment Facility

Metering inflows to the system

Change in Selenium in Control and in Treatment

T1 Selenium and T3 Selenium

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Aug Sep Oct Nov Dec J an

T1

Sele

niu

m L

bs. C

um

ula

tive

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

T3

Sele

niu

m L

bs. C

um

ula

tive

T1 Selenium Input T1 Selenium Discharge+P ool

T1 Selenium Residual T3 Selenium Input

T3 Selenium Discharge+P ool T3 Selenium Residual

Discharge of Selenium in Control and in Treatment

Ratio: (Discharge+Pool)/Input T1 Selenium and T3 Selenium

0%

20%

40%

60%

80%

100%

120%

Aug Sep Oct Nov Dec J anDate

Perc

ent dis

char

ge

T1 Selenium Ratio

T3 Selenium Ratio

Change in Se and NO3

Concentrations in the Project

pH EC (umhos/cm) B (ppm) Se (ppm) NO3-N (ppm) SO4 (ppm)SL 1 SL 2 SL 3 SL 1 SL 2 SL 3 SL 1 SL 2 SL 3 SL 1 SL 2 SL 3 SL 1 SL 2 SL 3 SL 1 SL 2 SL 3

T1 8.5 8.7 8.8 8190 14000 18200 10.3 18.8 26.7 0.214 0.41 0.618 44.3 16.2 40.4 3240 5050 67908.2 8.5 8.7 8650 14600 19700 11.7 18.4 28.1 0.216 0.377 0.646 47.8 11.5 37.5 3350 5410 7060

SL 1 SL 4 SL 5 SL 1 SL 4 SL 5 SL 1 SL 4 SL 5 SL 1 SL 4 SL 5 SL 1 SL 4 SL 5 SL 1 SL 4 SL 5

T2 8.5 8.8 8.6 8190 13400 15800 10.3 17.7 23.4 0.214 0.378 0.501 44.3 25.4 43.3 3240 4920 56308.2 8.6 8.5 8650 13800 16600 11.7 17.1 23.7 0.216 0.339 0.502 47.8 22.3 42.2 3350 5000 5720

SL 1 SL 6 SL 7 SL 1 SL 6 SL 7 SL 1 SL 6 SL 7 SL 1 SL 6 SL 7 SL 1 SL 6 SL 7 SL 1 SL 6 SL 7

T3 8.5 8.4 8.4 8190 14700 26900 10.3 19.4 40.9 0.214 0.042 0.0476 44.3 2.6 <0.1 3240 5300 102008.2 8.3 8.4 8650 15400 29500 11.7 19.6 43.1 0.216 0.0354 0.0441 47.8 <0.1 <0.1 3350 5560 11400

AGRARIAN’S DESIGN PROCESSDATA REVIEW

UNDERSTANDING THE PROBLEMPOLITICALECONOMICECOLOGICAL

INITIAL CONCEPTTHOUGHT EXPERIMENTS METHODS TECHNOLOGIES INFRASTRUCTURE

DESIGN

DEMONSTRATION PROJECTPROOF OF CONCEPT

EMPIRICAL EVALUATION

ACCEPT ELIMINATE MODIFY EXPAND

SCIENTIFIC INQUIRY ON PROCESS

RECOMMENDED ACTIONS

We are here

The Design SpiralStages:

Model Prototype Pre-implementation Implementation

Effectiveness

Technical feasibility

Sustainability

Efficiency

Costeffectiveness

Acceptability

Risk

Consensus

STAGES of the Design Spiral

MODELSmall scale, inexpensive, testing basic concepts, highly adapative

PROTOTYPELarger scale, testing for efficiency and cost effectiveness,

more process-oriented

PRE-IMPLEMENTATIONApproaches scale for a full project, involves optimization and

risk analysis

IMPLEMENTATIONA full-scale project that meets all criteria for regional applicability

Agrarian uses the design spiral as a tool for project development.

Project Type Size (acres) Cost (dollars) Criteria evaluated

Model 3 50,000 feasibility, effectiveness, sustainability

Prototype 10 500,000 as above, and efficiency, cost Pre-implementation 40 1,000,000 as above, and acceptability, risk

Implementation 100 3,000,000 as above, and regional consensus for long-term implementation

CRITERIA EVALUATEDin the Design Spiral

Effectiveness: does it work?Feasibility: is it practical?Sustainability: will it last?Efficiency: does it work well ?Life cycle cost: is it affordable?Acceptability: is it reasonable?Risk assessment: is it reliable and safe?Consensus: can we all agree on it?

Selenium removal in a farm setting: a model scale project

Testing effectiveness, feasibility, and sustainability

Agrarian’s Mission Statement

To develop solutions to land and water managementproblems that will be:

•effective•technologically feasible•sustainable•lowest in life cycle cost

We believe that small, passionately interestedteams with high capacity and creativity cansolve problems with unique effectiveness.

Such a team can:

•internalize the design process •move fast•take calculated risks•make our mistakes quickly•maximize gains

What it means for Agriculture

Solving problems is a team approach. The players are:•government agencies with vision, resources, and a sense of ownership in the problem•farmers or irrigation districts with the capacity to explore options•consultants with information and commitment to the project

The Task Force is an important first step in building an effective team. Keep it

FOCUSEDON TARGET

ACTIVECONTINUALLY EDUCATED

INTERACTIVEREALISTIC

and you are well on your way to developing solutions