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Coal Bed Methane Aquaculture

AquaMatrix carried out four research and development projects on the effects of coal bed methane on fish over a period of six years, from 2001 to 2007.  The first two projects were supported by the U.S. Department of Agriculture, the second two were supported by the National Science Foundation.  Dr. Woiwode served as Principal Investigator on all four CBM / fish research initiatives.


Coal Bed Methane Discharge Water

Vast volumes of water are a necessary though unwanted byproduct of the methane extraction process. The saline discharge is widely viewed as an environmental liability. Discharges into classified streams are essentially forbidden. Indiscriminant surface discharge can cause soil salination and sodification.
In 2001, AquaMatrix first examined the potential suitability of CBM discharge water for the culture of fish from a human health perspective, as there was widespread perception that this water was "tainted", and consumption of anything grown in it would be detrimental to human health. In research supported by the U.S. Department of Agriculture, we assayed for the bioconcentration of FDA targeted heavy metals (As, Cd, Cr, Hg, Ni and Pb) as well as 200 hydrocarbons in the edible muscle of rainbow trout that were grown directly in this water, in a classic bioassay experiment. All targeted heavy metals and hydrocarbons were below detectable limits.

With results providing a clean bill of health, we undertook additional research, again supported by the U.S. Department of Agriculture, to develop a technique for growing fish directly and intensively in CBM discharge water.  Initiated in 2002, for two years, we designed, developed and tested an intensive fish culture system that utilized the CBM discharge for the intensive production of the food fish tilapia. There were water chemical, engineering and management issues that we have resolved. With proper degas and regas of the water, careful management of the divalent cations (Mg, Ca)  and by recirculating the water through a bed of two species of beneficial bacteria, among other refinements and protocols, we developed an operational system capable of growing these fish at their optimums.  The greatest technical achievement of this research was the development of a balanced relationship between the excessive carbonate in the CBM water and the carbonate requirements of the beneficial bacteria, resulting in healthy fish and thriving bacteria.


Prototype CBM Fish Culture Facility


Four wing salt bush (Atriplex canescens) with salt from CBM water crystalized in leaf tissue.

We had always recognized that our two initial fish projects did not necessarily resolve the problem of surface CBM discharge; rather it made an asset out of a perceived liability, a classic case of industrial ecology.  However, we felt there should be a way to improve land quality, produce beneficial plant and fish crops, and simultaneously address CBM surface discharge issues.  Our perspective was that an agronomic model could be developed that could accomplish all of these goals by intensively growing the fish in the CBM water, then applying the manures from the fish facility onto halophytic plants.  We forecast that the halophytic plants would take up sodium from the CBM water, and that this rate and volume of sodium uptake would be accelerated by the application of the manures from the fish grown in the CBM water.  We also forecast that the soil tilth would improve under this protocol, a complete reversal of salination damage caused by CBM irrigation.

In 2003, we undertook research supported by the National Science Foundation to address these hypotheses.  Our experimental design documented the sodium uptake and soil permiability changes by halophytes irrigated with CBM discharge water enhanced with nutrients from fish farm effluent. Three halophytic plants were tested: four wing salt bush, malting barley and crested wheat grass. Four water treatments were utilized: CBM water, CBM water with a prescribed amount of fish manure, CBM water applied to plants fertilized with inorganic fertilizers, and spring water.

Our results were significant and profound:
* Plants irrigated with CBM water contained an order of magnitude higher Na levels incorporated into the plant tissue (mg/kg) than plants irrigated with spring water.
* Plants irrigated with CBM water and fish manures had 2-300% greater growth than those irrigated with CBM water or control spring irrigation water.
* The plants irrigated with CBM with fish manures contained yet an additional 200-300% more Na/kg than those not fertilized.
* All plants receiving fish manures were the same in total yield and sodium concentration as those plants fertilized with costly commercial fertilizer, despite much lower N and P levels in the manures.
* Total sodium removal by four wing salt bush grown with CBM water and fish manures was 18.3 kg/acre, and 38.5 kg/acre with malting barley.
* Soil remained below the target SAR of 10 for all CBM irrigated treatments.

This research phase exceeded our expectations, and led us to forecast a predictive agronomic model of intensive fish production - halophytic plant production - CBM discharge water surface application that results in a predictable, consumptive, agricultural use of the CBM water. Consumption of sodium as well as beneficial changes in soil structure under this protocol could affect disharge permitting, as the discharge would then be a "land application", following EPA's highest priority Best Management Practices ("BMPs") of surface application of fish farm effluent on agricultural crops.

In research - again supported by the National Science Foundation - we expanded this experimental protocol to full field trials.  We constructed a larger intensive fish production facility to produce field trial manures.  We planted eight halophytic plant groups x five water qualities x four reps for 160 10x15' plots.
 The final results of the NSF project were presented at the World Aquaculture Society conference in Busan, Korea, May, 2008.  The abstract, including the final agronomic model recommendations, are provided.


Tilapia in the CBM Production Facility, Wyoming.

The Use of Intensively Cultured Fish and Halophytic Plants for the Bioremediation of Coal Bed Methane Discharge Water

John G. Woiwode, Kevin Fitzsimmons, James Walworth

An agronomic model for the bioremediation of the environmentally contentious Coal Bed Methane (CBM) discharge water was developed and tested.  CBM discharge, amended with prescribed amounts of tilapia effluent, was irrigated onto eight halophytic plant species.

Sodium uptake and biomass production were significantly enhanced in all plants, and percolation of salts was increased through the soil past the root zones, by the addition of prescribed amounts of fish effluent.  Specifically:
  • Plants irrigated with CBM water contained an order of magnitude higher Na incorporated into the plant tissue than plants irrigated with control spring water.
  • The plants irrigated with CBM plus fish effluent and 2x fish effluent took up approximately 200% more Na/kg and had approximately 200% greater productivity than those irrigated with CBM water or control spring water.
  •  Sodium uptake was significantly greatest in hay barley and malt barley.
  • The amount of sodium retained in the root zone soil was least in the CBM + 2 Fish, which averaged 292 kg/ha.  Un-amended CBM treatments averaged 67% greater soil salinity, 488 kg/ha. 
  • Soil Sodium Adsorption Ratio (SAR) was significantly reduced in both shallow (0 – 15 cm) and deep (15 – 30 cm) soil profiles by the addition of fish effluent, and remained significantly below the target value of 10 in all CBM treatments.
  • The productivity and sodium concentrations of all plant treatments receiving fish effluent were significantly higher than those plants fertilized with inorganic fertilizer, despite two orders of magnitude lower N and P levels in the fish effluent.

Based on our data, an agronomic model was proposed: 2415 ml concentrated fish effluent to be irrigated per square meter onto hay or malt barley crop during the crop cycle.  50 metric tons of fish/yr consume 60 tons of feed; each ton of feed would produce 2558 liters of concentrated fish effluent; 50 tons of fish production would be enough to irrigate 63.6 hectares, using 55 cm water/ha.  This treatment provided the combination of greatest sodium uptake into the plant (2.71 %) plus the lowest residual sodium in the upper and lower soil profiles (only 33% of applied sodium remained in the soil profiles tested, less than half the un-amended CBM treatment).  The model provides effective sodium uptake, sustainable plant growth, and sustainable soils.