Bio-remediation for Selenium Making it Work for Agriculture
Jan 16, 2016
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