Identification of Possible Migration of Contaminants in Groundwater at a Landfill – A Case Study of Oman

In this study exploratory borehole drilling along with soil core sampling, chemical analysis, piezometer construction, field and laboratory hydrochemical analyses and pumping test were applied. The main aim was to understand the extent of contamination and contaminant movement in the unsaturated zone and groundwater at a dumping site in Northern part of Oman (Barka dumping site). Water samples were analyzed for inorganic, organic and biological characterization to identify any potential contamination of groundwater from Barka dumping site. Results showed elevated concentration of TDS, Na, Ca, Mg, alkalinity, chloride and total hardness. Thus, indicated that the groundwater below the dumping site is strongly affected by leachate originated from liquid lagoons located in and around the landfill. Furthermore, microbiological parameters showed that groundwater beneath Barka dumping site is largely influenced by bacterial contamination with total coliform and E.coli. Keywords: Borehole drilling; dumping site; groundwater contamination; unsaturated zone; contaminant transpor

Artificial Neural Network Modeling of Distillers Dried Grains with Solubles (DDGS) Flowability with Varying Process and Storage Parameters

Neural network (NN) modeling techniques were used to predict flowability behavior of distillers dried grains with solubles (DDGS) prepared with varying levels of condensed distillers solubles (10, 15, and 20%, wb), drying temperatures (100, 200, and 300°C), cooling temperatures (–12, 25, and 35°C), and storage times (0 and 1 month). Response variables were selected based on our previous research results and included aerated bulk density, Hausner ratio, angle of repose, total flowability index, and Jenike flow index. Various NN models were developed using multiple input variables in order to predict single-response and multiple-response variables simultaneously. The NN models were compared based on R², mean square error, and coefficient of variation obtained. In order to achieve results with higher R² and lower error, the number of neurons in each hidden layer, the step size, the momentum learning rate, and the number of hidden layers were varied. Results indicate that for all the response variables, R² > 0.83 was obtained from NN modeling. Compared with our previous studies, NN modeling provided better results than either partial least squares modeling or regression modeling, indicating greater robustness in the NN models. Surface plots based on the predicted values from the NN models yielded process and storage conditions for favorable versus cohesive flow behavior for DDGS. Modeling of DDGS flowability using NN has not been done before, so this work will be a step toward the application of intelligent modeling procedures to this industrial challenge