title: 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.
authors.affiliation: Department of Civil & Environmental Engineering, University of Maryland, College Park, Maryland 20742, USA. sgabriel@umd.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Gabriel
authors.forename: Sirapong
authors.initials: S
authors.lastname: Vilalai
authors.forename: Susanna
authors.initials: S
authors.lastname: Arispe
authors.forename: Hyunook
authors.initials: H
authors.lastname: Kim
authors.forename: Laura L
authors.initials: LL
authors.lastname: McConnell
authors.forename: Alba
authors.initials: A
authors.lastname: Torrents
authors.forename: Christopher
authors.initials: C
authors.lastname: Peot
authors.forename: Mark
authors.initials: M
authors.lastname: Ramirez
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004219:District of Columbia; D004220:Disulfides / Q000032:analysis*; D005544:Forecasting; D015233:Models, Statistical; D009812:Odorants / Q000032:analysis*; D012044:Regression Analysis; D012722:Sewage; D014865:Waste Disposal, Fluid
chemical_list: D000393:Air Pollutants; D004220:Disulfides; D012722:Sewage; C021181:dimethyl disulfide