Lian-Shin Lin

As(iii) removal using an iron-impregnated chitosan sorbent.

An iron-impregnated chitosan granular adsorbent was newly developed to evaluate its ability to remove arsenic from water. Since most existing arsenic removal technologies are effective in removing As(V) (arsenate), this study focused on As(III). The adsorption behavior of As(III) onto the iron-impregnated chitosan absorbent was examined by conducting batch and column studies. Maximum adsorption capacity reached 6.48 mg g(-1) at pH=8 with initial As(III) concentration of 1007 microg L(-1). The adsorption isotherm data fit well with the Freundlich model. Seven hundred and sixty eight (768) empty bed volumes (EBV) of 308 microg L(-1) of As(III) solution were treated in column experiments. These are higher than the empty bed volumes (EBV) treated using iron-chitosan composites as reported by previous researchers. The investigation has indicated that the iron-impregnated chitosan is a very promising material for As(III) removal from water.

Effects of highway construction on stream water quality and macroinvertebrate condition in a Mid-Atlantic Highlands watershed, USA.

Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

Kinetics and microbial ecology of batch sulfidogenic bioreactors for co-treatment of municipal wastewater and acid mine drainage

The kinetics and microbial ecology in sulfidogenic bioreactors used in a novel two-stage process for co-treatment of acid mine drainage (AMD) and municipal wastewater (MWW) were investigated. Michaelis-Menten modeling of COD oxidation by sulfate reducing bacteria (SRB) (Vmax=0.33mgL(-1)min(-1), Km=4.3mgL(-1)) suggested that the Vmax can be reasonably achieved given the typical COD values in MWW and anticipated mixing with AMD. Non-competitive inhibition modeling (Ki=6.55mgL(-1)) indicated that excessive iron level should be avoided to limit its effects on SRB. The COD oxidation rate was positively correlated to COD/sulfate ratio and SRB population, as evidenced by dsrA gene copies. Phylogenetic analysis revealed diverse microbial communities dominated by sulfate reducing delta-proteobacteria. Microbial community and relative quantities of SRB showed significant differences under different COD/sulfate ratios (0.2, 1 and 2), and the highest dsrA gene concentration and most complex microbial diversity were observed under COD/sulfate ratio 2. Major species were associated with Desulfovirga, Desulfobulbus, Desulfovibrio, and Syntrophus sp. The reported COD kinetics, SRB abundances and the phylogenetic profile provide insights into the co-treatment process and help identify the parameters of concerns for such technology development.

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...

Tracking Effects of Pollution Sources on In-stream Water Quality Using a Modeling Approach

This paper presents a modeling approach that establishes cause-effect relationship between individual pollution sources and in-stream water quality. It introduces a conceptual model of constituent network that mimics in-stream water quality dynamics. The network consists of water quality constituents (e.g., nutrients, DO, algae) and links among the constituents, which are the fundamental processes that convert chemical/biological mass from one constituent to another (e.g., algal growth). The network structure allows implementation of a tracking algorithm that quantifies the mass flux transferred among constituents via the processes. Impact of a pollution source is viewed as mass flux propagating through the constituent network and is quantified by the tracking algorithm. This approach makes differentiating impacts of individual sources on water quality feasible. In addition, the approach can be used to examine interactions of multiple pollution sources and their effects on reaction kinetics. Monitoring propagation of the mass flux in each river segment also can help investigate how small-scale process dynamics affects large-scale watershed response such as pollutant export from the river system. The proposed methodology is useful for assisting regulatory programs such as the Total Maximum Daily Load (TMDL) for setting load/wasteload allocations and nutrient trading. It also is a useful tool for formulating effective best management practices and developing watershed management plans.