Publications

Evaluation of InSpectra UV Analyzer for Measuring Conventional Water and Wastewater Parameters

Lizette R. Chevalier et al. — Mon, 10 Aug 2009 12:06:34 PDT

A relatively new analytical instrument for the measurement of BOD5, COD, TSS, TOC, nitrates and surfactants has been developed commercially. It is based on the use of ultraviolet spectrophotometry and a deterministic approach to analyze the sample’s spectrum by comparing it with a series of historical reference spectra. Using standard methods for the measurement of BOD5, TSS and TOC as true values, the use of this instrument was evaluated. The samples tested were obtained from both wastewater and water treatment facilities. Results indicate that the BOD5 measurement performed best. There was no correlation found for TSS or TOC.

Feasibility of Calcium Peroxide as an Oxygen Releasing Compound in Treatment Walls

Lizette R. Chevalier et al. — Mon, 10 Aug 2009 09:53:26 PDT

This research investigates the use of a proprietary formulation of powdered calcium peroxide (PermeOx Plus®) as an oxygen releasing compound in a treatment wall. Laboratory scale column studies evaluated the release of oxygen and the permeability effects resulting from a treatment wall mixture of the calcium peroxide and a representative aquifer sand (40-mesh Unimin sand). The mixtures evaluated ranged from 0.1 to 1.0 percent by weight. Influent water was prepared at an average dissolved oxygen concentration of 3.1 mg/L and pumped into the treatment wall soil at a constant rate of 0.17 cm³/sec (0.53 ft³/day) to simulate ground water dissolved oxygen and flow conditions. The average changes in relative permeability for mixtures of 0.1%, 0.5% and 1.0% calcium peroxide by weight were 65.6%, 66.1% and 77.1%, respectively. The peak dissolved oxygen levels in the same mixtures were 5.9, 7.40, and 10.7 mg/L, respectively.

Use of Optimization to Develop a Correlation Model for Predicting Residual NAPL Saturation

Lizette R. Chevalier — Mon, 10 Aug 2009 09:38:50 PDT

Predicting the residual saturation of a trapped non-aqueous phase liquid contaminant is critical to estimating the region of contamination, the design of remediation strategies, and risk assessment. Models were developed to predict residual NAPL saturation utilizing optimization and non-linear error functions, consequently allowing for a broader mathematical approach to model development. The input parameters evaluated represent soil and fluid properties: the uniformity coefficient (C_u), the coefficient of gradation (C_c), the capillary number (Nc), the bond number (Nb) and the total trapping number (Nt). Overall, the model that performed best was based on a second-order equation with the independent variables C_u and Nt₁ using the sum of the squares of the errors. The nonlinear error function based on a derivative of Marquardt’s Percent Standard Deviation performed best for three other cases.