Prediction of Dimethyl Disulfide Levels from Biosolids Using Statistical Modeling

Abstract

Two statistical models were used to predict the concentration of dimethyl disulfide (DMDS) released from biosolids produced by an advanced wastewater treatment plant (WWTP) located in Washington, DC, USA. The plant concentrates sludge from primary sedimentation basins in gravity thickeners (GT) and sludge from secondary sedimentation basins in dissolved air flotation (DAF) thickeners. The thickened sludge is pumped into blending tanks and then fed into centrifuges for dewatering. The dewatered sludge is then conditioned with lime before trucking out from the plant. DMDS, along with other volatile sulfur and nitrogen-containing chemicals, is known to contribute to biosolids odors. These models identified oxidation/reduction potential (ORP) values of a GT and DAF, the amount of sludge dewatered by centrifuges, and the blend ratio between GT thickened sludge and DAF thickened sludge in blending tanks as control variables. The accuracy of the developed regression models was evaluated by checking the adjusted R2 of the regression as well as the signs of coefficients associated with each variable. In general, both models explained observed DMDS levels in sludge headspace samples. The adjusted R2 value of the regression models 1 and 2 were 0.79 and 0.77, respectively. Coefficients for each regression model also had the correct sign. Using the developed models, plant operators can adjust the controllable variables to proactively decrease this odorant. Therefore, these models are a useful tool in biosolids management at WWTPs.

Statistical Biosolids Odor Predicting Models Using Processing Parameters at Blue Plains Advanced Wastewater Treatment Plant

“…al., 2006;Gabriel et. al., 2005;Vilalai, 2003), the approach described in this research is unique since both sensory measurements and analytical odor measurement techniques were applied to assess biosolids odor levels.…”

Multi-objective Optimization Models for Distributing Biosolids to Reuse Fields: A Case Study for the Blue Plains Wastewater Treatment Plant

“…Determining the odor footprint though is not an easy task given the complexity of how humans perceive these odors. Nevertheless, recently, there have been a good number of studies that try to gauge the odor impact of biosolids taking into account wastewater treatment processes as well as ambient conditions (Kim et al 2002(Kim et al , 2003Gabriel et al 2005Gabriel et al , 2006bJanpengpen 2006). Additionally, Intarakosit (2006) constructed an odor dispersion model for measuring the effect of biosolids odor in reuse fields.…”

Real-Time Monitoring and Forecasting of Odor After Dewatering in Wastewater Treatment

“…In the last few years, DCWASA has researched statistical odor forecasting models to predict the odor levels based on ambient conditions. Gabriel, et al (2005) identified dimethyl disulfide levels from biosolids by using statistical modeling, and Gabriel, et al (2006) using statistical modeling to forecast odor levels of biosolids applied to reuse sites. The present research excludes that work by comparing odors with process data before biosolids are delivered to the field.…”

“…At DCWASA, several studies are underway to minimize odors. These include investigating the amount of odor released when different amounts of lime are incorporated into samples (Murthy 2002a), forecasting odor levels for biosolids product based on ambient conditions (Vilalai 2003), prediction of dimethyl disulfide levels from biosolids using statistical modeling (Gabriel, et al 2005), statistical modeling to forecast odor levels of biosolids applied to reuse site (Gabriel, et al 2006), and an evaluation of methods for qualifying lime incorporation into mechanically dewatered sludge (North 2003). In addition, other studies have investigated the potential for odor release when a sludge sample is contained in the Teflon tube opened for 30 minutes, 24 hours, and seven days.…”