As a continuation of our course project due in Unit VIII (a proposal for an industrial and hazardous waste treatment facility), complete the next (fifth) section (biological and secondary treatm
MEE 5801, Industrial and Hazardous Waste Management 1 Cou rse Learning Outcomes for Unit V Upon completion of this unit, students should be able to: 1. Assess the fundamental science and engineering principles applicable to the management and treatment of solid and hazardous wastes . 5. Evaluate operations and technologies related to industrial and hazardous wastes. 5.1 Discuss the necessary design features of a secondary settlement tank. 5.2 Discuss the necessary design features of a biological filtration system. Reading Assignment Chapter 7: Sewage Treatment Unit Lesson While we allow Bahadori (2014) to discuss sewage treatment systems within t he context of the required reading for Unit V, we are going to spend a little time considering one of the ancillary aspects of sewage treatment involving hydrocarbon -lade n liquid wastes. Bahadori (2014 ) discusses some areas of this topic in our suggested reading for this unit, but an overview of his presentation may help us better because of some often overlooked independent variables causally related to the safety of an industrial and hazardous waste treatment system. One of the critical variables relate d to the safety of a treatment system is the air quality surrounding the processes, particularly when hydrocarbons are present in the influent waste streams. As such, it is imperative that we understand the relationship of solubility of certain petroleum -related organic compounds and hydrocarbons in water, as well as their relative emission rates coming from the wastewater during the processes. By definition, a hydrocarbon is a compound containing only two elements, carbon and hydrogen (Hill & Feigl, 1987 ). While we were likely able to decant and remove much of the visible hydrocarbon and petroleum - related organic compounds from the wastewater during the physical treatment process of our system, the lighter organic compounds (specifically the light alkanes methane and ethane) may be persistent in the wastewater (Bahadori, 2014). These alkanes are sometimes called saturated hydrocarbons , due to the fact that each carbon atom is bonded with four hydrogen atoms with no double or triple bonds (Hill & Feigl, 198 7). This is further complicated with the fact that these two compounds typically have very low solubility in water, and subsequently are emitted as gases in the process (Bahadori, 2014; Ha as & Vamos, 1995). As such, these compounds pose threats to the safe ty of the process work environment, given that both methane and ethane have relatively low flashpoints. For example, methane (CH 4) has a flashpoint of −368.6ºF and lower explosive limit of 5.3%, and ethane (C 2H6) has a flashpoint of −202ºF and a lower expl osive limit of 3.0% (Lewis, 1991). One could only imagine the threat of spark in this environment while operating the treatment process. Consequently, it is important for us as engineers to anticipate the aqueous solubility of these saturated hydrocarbons in the wastewater as a means of forecasting the emissions from the process. Bahadori (2014) presents his previous work to demonstrate calculated coefficients that can be used to correlate the mole fractions of individual components of a hydrocarbon -laden solution and subsequently reduced partial pressure of the solution. The tabulated coefficients are presented for both methane and ethane, with a follow -on formula for forecasting the hydrocarbon -water solubility of these two alkanes, as well UNIT V STUDY GUIDE Designing Liquid Waste Management Systems for Industrial and Hazardous Waste MEE 5801, Industrial and Hazardous Waste Management 2 UNIT x STUDY GUIDE Title as the rest o f the continuous -chain alkane ranges of propane (C 3H8) through hexane (C 6H14) and hexane through decane (C 10H22) (Bahadori, 2014; Hill & Feigl, 1987). Finally, the dissolved organic carbon (DOC) can then be anticipated in units of percent by weight for each petroleum -related compound and subsequently correlated as a ratio of DOC to chemical oxygen demand (COD) or DOC/COD. As such, a predicted value for DOC derived from the DOC/COD ratio (0.267) may be calculated solely from the COD measurements (Bahadori , 2014). For example, if a petroleum -laden wastewater has a COD value of 500 ppm, the anticipated calculation for predicting DOC could be made as follows (Bahadori, 2014): DOC/COD = 0.267 Where DOC = X COD = 500 ppm then X/500 ppm = 0.267 or X = 500 ppm (0.267) so X = 133.5 ppm or DOC = 133.5 ppm Still, Bahadori (2014) presents additional tabulated information derived from historical DOC concentration measurements from refinery effluents for both organics and inorganics traditionally found in those waste streams. You may find this information useful in your own engineering work for your industrial and hazardous waste treatment system currently under design in this class. Remember that the ultimate reason for predicting the DOC concentrations in the wastewater is to mitigate hazardous environmental conditions for both humans and the ecological life surrounding and interacting with the treatment process. As such, you may consider the relative intrinsic safety of pumps, motors, mixers, and other equipment that is designed into the process as part of the system. Let’s return to our interactive model and design in the biological and secondary treatment phase of our proposed industrial and hazardous waste treatment system. 1. Click here to access the interactive design model. 2. Closely review the influent laboratory report (lift station) against the efflue nt laboratory report (pop up report). Remember that the goal is to design our system so that the final effluent concentrations meet the established local limits for the municipal WWTP. 3. Continue to use this model in your design work for your course project (proposed in dustrial and hazardous waste treatment facility ) again in this unit . Notice that as you design the next -to-last phase of this system, the process is noticeably dropping the concentrations of the constituents of concern. Your process is becoming more efficient with every design phase of the system! References Bahadori, A. (2014). Waste management in the chemical and petroleum industries. West Sussex, United Kingdom: Wiley. Haas, C., & Vamos, R. (1995). Hazardous and industrial waste t reatment . Upper Saddle River, NJ: Prentice - Hall. MEE 5801, Industrial and Hazardous Waste Management 3 UNIT x STUDY GUIDE Title Hill, F., & Feigl, D. (1987). Chemistry and li fe: An introduction to general, organic, and biological chemistry . New York, NY: MacMillan. Lewis, R. (1991). Hazardous chemicals desk reference (2nd ed.). New York, NY: Van Norstrand Reinhold. Suggested Reading The suggested reading from the textbook will give you additional resources related to the content for this Unit. Chapter 5: Wastewater Treatment in Unconventional Oil and Gas Industries Chapter 6: Wastewater Sewer Systems