Karen M. Buzby

Structural and functional aspects of treated mine water and aquaculture effluent streams

Multiple effluent streams may flow into a single receiving stream making it difficult to understand the effects of a single effluent source or the interactions between effluents. In this study, we examined benthic community structure and function in an effluent stream formed by the release of treated mine water, in treated mine water that had been used as a water source for flow-through aquaculture and below the confluence of the two. This study demonstrated that macroinvertebrate communities, while taxonomically simple, developed in treated mine water. The addition of aquaculture effluent to the treated mine water allowed colonization by additional taxa, increased leaf decomposition rates and may have conferred resistance to a turbidity event. Ecosystem responses were mediated by the surrounding terrestrial environment. In shaded conditions macroinvertebrate densities could be as much as 10× higher and the taxa were dominated by simuliids and chironomids, while in open conditions filamentous algae flourished and the taxa were dominated by hydroptilids and chironomids. Consequently, consideration of stream processes that promote preferred ecological processes, such as macroinvertebrate production and organic matter processing, when siting effluent streams may reduce impacts on receiving streams.

A case study for orphaned chemicals: 4-methylcyclohexanemethanol (MCHM) and propylene glycol phenyl ether (PPH) in riverine sediment and water treatment processes.

There are an estimated 30,000 chemicals in commerce used in quantities >1016kg per year in the US. Unfortunately there is limited information on the chemicals partitioning and reactivity properties. These orphaned or understudied chemicals are viewed as non-hazardous but can still pose serious economic, health, environmental and societal impacts as evidenced by the January 2014 spill of 37,900L of crude-MCHM (primarily 4-methylcyclohexanemethanol) and stripped-PPH (primarily dipropylene glycol phenyl ether and propylene glycol phenyl ether) into the Elk River near Charleston, WV. Using the Elk River spill as a case study of orphaned or understudied chemicals, experiments were undertaken to evaluate the adequacy of standard approaches to emergency drinking water treatment (oxidation and sorption to activated carbons). Further available sorption models for estimating the potential of these compounds to sorb to Elk River sediments and to activated carbons in drinking water systems were investigated. The results showed that powdered activated carbon (PAC) was the most effective sorbent. The trans-MCHM isomer was found to preferentially sorb compared to cis-MCHM. For MCHM concentrations ranging from 2 to 5mgL-1 in the treatment plant, PAC concentrations of 0.1-1.4mgL-1 would be required to lower both MCHM isomers to the CDC screening level. In most cases, published linear solvation energy relationships and quantitative structure activity relationships were inadequate to estimate the a priori likelihood of sorption of MCHM and PPH to sediments and GAC, but did fit the PAC results well. Permanganate and chlorine oxidation of the compounds showed limited to insignificant removal. The studies presented herein suggest that there are still inherent vulnerabilities to drinking water treatment systems that need to be addressed.

Remediation of Flow-Through Trout Raceway Effluent via Aquaponics

AbstractProduction and nutrient removal were assessed for three vegetable crops (kohlrabi, lettuce, and Swiss chard) and two edible flowers (calendula and nasturtium) grown entirely on effluent from a flow-through trout raceway. Soluble nutrient concentrations in the effluent averaged 0.56 and 0.19 mg/L for total nitrogen and soluble reactive phosphate, respectively. Seeds were sown into Styrofoam trays filled with vermiculite and placed directly into the plant growing channels. Lettuce was harvested at 6, 9, and 12 weeks for a total mean harvest biomass of 4.5 kg/m2. Kohlrabi and Swiss chard were harvested at 12 weeks, with a mean harvest biomass of 15.4 and 7.5 kg/m2, respectively. Harvest biomass of kohlrabi was significantly greater than that of lettuce or Swiss chard. Nasturtium flowers were harvested at 9 and 12 weeks, while calendula did not begin to produce flowers until 12 weeks. There were no significant differences in percent removal of total ammonia nitrogen (TAN), nitrate, or phosphate at 6 w...

Evaluation of Lettuce Between Spring Water, Hydroponic, and Flow-through Aquaponic Systems

ABSTRACT Lettuce (Lactuca sativa L.) is an important vegetable crop that can be grown in hydroponic and aquaponic systems. A comparative study to evaluate the efficacy of a cold water flow-through aquaponic system (FTS) to a hydroponic system is lacking. Twenty-seven lettuce cultivars with green or red leaves, in seven subtypes, belonging to four popular types in the Western diet, were grown in spring water or aquaponic or hydroponic treatments. Spring and aquaponic water flowed directly from a spring and a raceway growing rainbow trout, respectively. The hydroponic treatment had nutrients added to a recirculated system. Stand establishment, average yield, and productivity (yield/week) were determined for each subtype or cultivar and compared among water treatments. No comparison among lettuce types, subtypes, or cultivars was made due to inherent differences among genotypes. Total yield and productivity (402.5 g·m−2 and 4.9 kg/tray/week, respectively) in the FTS were lower than those in the hydroponic system (468.9 g·m−2 and 6.7 kg/tray/week, respectively). Average yields of butterhead and bibb subtypes in aquaponics were higher than in the hydroponic treatment. Bibb subtype lettuces performed better in the aquaponic treatment, and average yields of butterhead and romaine, one of the most popular and nutritious lettuce types, were similar to those in the hydroponic treatment. The cvs. Outredgeous in romaine, Winter Density in bibb, Red Sails in leaf, and Red Saladbowl in oakleaf subtypes were recommended for an FTS. Average yields of green lettuces were higher than red lettuces in the bibb subtype in all treatments. Lettuce yield, depending on cultivar, could be comparable to hydroponic or field production based upon yield per area.