Time‐Dependent Retardation Model for Chemical Oxygen Demand Removal in a Subsurface‐Flow Constructed Wetland for Winery Wastewater Treatment

Abstract

The relative success of chemical oxygen demand (COD) removal models to describe measured rates of COD removal in a pilotscale constructed wetland designed for treatment of high-strength winery wastewater are evaluated using retention times determined from tracer studies. Not surprisingly, two-parameter residual and retardation models better fit the measured removal data than single-parameter, first-order decay models for wastewater at average COD loadings up to nearly 5000 mg/L. The residual and retardation models yielded nearly equivalent fits to the measured data. However, the retardation model had more consistent parameters for COD removal data across different depth levels in the constructed wetland and at different loadings, and a slightly smaller sum of least-squared errors. The retardation model seems to be appropriate for constructed wetland design because it allows a steady decrease in COD with increased treatment time rather than a constant residual COD (C*) value. From the least-squares optimization procedure used to estimate model parameters (a volumetric rate constant, K v , range o f3t o1 2d Ϫ1 ), nonrealistic, or physically meaningless, large C* values (C* range of 23 to 450 mg COD/L) that were dependent on COD loading were obtained, potentially underestimating the constructed wetland system's actual winery wastewater treatment potential. The optimal parameters for the retardation model applied to the pilot-scale constructed wetland ranged from 9 to 12 d Ϫ1 for the initial degradation rate constant, K o ,a n d2t o5d Ϫ1 for the time-based retardation coefficient, b. These values should be verified for full-scale field systems based on field measurements currently underway. Water Environ. Res., 73, 597 (2001).

On the fit of statistical and thek-C* models to projecting treatment performance in a constructed wetland system

“…In the literature, a range of 1.7 ≤ C * ≤ 18.2 mg/L BOD 5 with a mean of 9.9 was reported by Stein et al [9] and Kadlec and Knight, [10] respectively, while Shepherd et al [19] reported a range of 23 ≤ C * ≤ 450 mg/L COD in a CWs treating winery wastewater.…”

An Annual and Seasonal Characterisation of Winery Effluent in South Africa

“…Thus, substantially different rate constants for the reduction of the COD would be found in each case. It is common practice in the literature to specify a biodegradation rate constant for the reduction of COD (or biological oxygen demand, BOD) for a given effluent (Wood, 1995;Kadlec & Knight 1996;Shepherd et al, 2001), and to utilise these in process models for the design of effluent treatment technologies.…”

Assessment of temporal and spatial evolution of bacterial communities in a biological sand filter mesocosm treating winery wastewater

“…, ; Shepherd et al . ,b), the microbial communities, which are known to play a fundamental biodegradative role (Stottmeister et al . ; Truu et al .…”