Inputs of disinfection by-products to the marine environment from various industrial activities: Comparison to natural production

Highlights: • Overview on oxidative treatment processes for different industrial applications • Compilation of disinfection by-product types/concentrations in marine water uses • Estimation of global DBP inputs into marine water from different industries • Comparison of anthropogenic bromoform production to emissions from natural sources Abstract: Oxidative treatment of seawater in coastal and shipboard installations is applied to control biofouling and/or minimize the input of noxious or invasive species into the marine environment. This treatment allows a safe and efficient operation of industrial installations and helps to protect human health from infectious diseases and to maintain the biodiversity in the marine environment. On the downside, the application of chemical oxidants generates undesired organic compounds, so-called disinfection by-products (DBPs), which are discharged into the marine environment. This article provides an overview on sources and quantities of DBP inputs, which could serve as basis for hazard analysis for the marine environment, human health and the atmosphere. During oxidation of marine water, mainly brominated DBPs are generated with bromoform (CHBr3) being the major DBP. CHBr3 has been used as an indicator to compare inputs from different sources. Total global annual volumes of treated seawater inputs resulting from cooling processes of coastal power stations, from desalination plants and from ballast water treatment in ships are estimated to be 470 – 800 × 109 m3, 46 × 109 m3 and 3.5 × 109 m3, respectively. Overall, the total estimated anthropogenic bromoform production and discharge adds up to 13.5 – 21.8 × 106 kg/a (kg per year) with contributions of 11.8 – 20.1 × 106 kg/a from cooling water treatment, 0.89 × 106 kg/a from desalination and 0.86 × 106 kg/a from ballast water treatment. This equals approximately 2 – 6 % of the natural bromoform emissions from marine water, which is estimated to be 385 – 870 × 106 kg/a

Math-model based gear -shift control strategy for advanced vehicle powertrain systems.

As vehicle powertrain systems become more and more complex with the integration of advanced technologies (e.g., electronic throttle control, variable displacement), it is becoming ever so difficult to obtain an optimal gear-shift control strategy using the current practice since it is frequently based on the experience and know-how of the calibration engineers and tuned in a heuristic manner. To overcome the short comings of the current practice, a math-model based design procedure based on the dynamic programming method is developed to generate optimal control strategy for vehicle powertrain systems. This computer-based procedure can accelerate the design process and achieve guaranteed performance level. Moreover, it is re-usable and more flexible that it can be applied to various configurations of the powertrain system with more advanced components. To illustrate the design procedure in detail, the gear-shift control of a vehicle with conventional powertrain system (i.e., 4-speed AT and engine) was optimized for best fuel economy while satisfying a prescribed drivability requirement using step throttle launching maneuvers. The resulting gear-shift map achieved better drivability and fuel economy than the current production map of the target vehicle. Also, the development time for a gear-shift map was significantly reduced (days vs. months). Then, based on this procedure, simultaneous control of the throttle and the gear of a powertrain system with Electronic Throttle Control (ETC) were optimized. The resulting throttle/gear map satisfied the driver's demand (power) in a more reliable and efficient way. Also, optimal gear control strategy was investigated for powertrain systems with variable displacement technology. These case studies showed the flexibility of the design procedure where it can be used for any combination of the powertrain system. In addition, dynamic programming is used to optimize the powertrain system following a fuel economy test drive cycle. This concept can be used to evaluate the fuel efficiency of new powertrain technologies and/or various configurations of the powertrain system as a technology assessment tool. The proposed design procedure was found to be more efficient (better result in much less time) in producing an optimal gear control strategy. It also proved to be flexible and can be applied to more advanced powertrain systems with unconventional configurations, which the current practice is not able to handle.Ph.D.Applied SciencesAutomotive engineeringMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126074/2/3224923.pd

Characteristics and Stability of Ozone Nanobubbles in Freshwater Conditions

The characteristics and stability of ozone nanobubbles (NBs) were investigated for the first time under different preparation conditions and freshwater conditions (i.e., pH, natural organic matter [NOM], carbonate, calcium, and temperature) for an extended period. Two oxygen gas flow rates (4 and 1 L/min) used in ozone NB generation affected the characteristics and stability of ozone NBs. The ozone NBs generated at a high initial dissolved ozone (12.5 mg/L) concentration showed a much higher brightness during measurements than the ozone NBs generated at a low initial dissolved ozone concentration (1 mg/L). The former also exhibited a higher negative surface charge and higher stability in comparison to the latter. The stability and half-lives of ozone NBs followed the order of 3 mM Ca2+ < pH 3 < NOM with high specific ultraviolet absorbance at 254 nm (SUVA254 = 4.1 L/mg·m) < pH 7 < pH 9, while the effects of carbonate and temperature were insignificant. Ozone NBs were relatively stable in waters for a long period (e.g., ≥ 60 days) except for high hardness or low pH conditions. Higher levels of hydroxyl radicals were produced from ozone NB solutions as compared to conventional ozonation

The roles of tertiary amine structure, background organic matter and chloramine species on NDMA formation

N-nitrosodimethylamine (NDMA), a probable human carcinogen, is a disinfection byproduct that has been detected in chloraminated and chlorinated drinking waters and wastewaters. Formation mechanisms and precursors of NDMA are still not well understood. The main objectives of this study were to systematically investigate (i) the effect of tertiary amine structure, (ii) the effect of background natural organic matter (NOM), and (iii) the roles of mono vs. dichloramine species on the NDMA formation. Dimethylamine (DMA) and 20 different tertiary aliphatic and aromatic amines were carefully examined based on their functional groups attached to the basic DMA structure. The wide range (0.02-83.9%) of observed NDMA yields indicated the importance of the structure of tertiary amines, and both stability and electron distribution of the leaving group of tertiary amines on NDMA formation. DMA associated with branched alkyl groups or benzyl like structures having only one carbon between the ring and DMA structure consistently gave higher NDMA yields. Compounds with electron withdrawing groups (EWG) reacted preferentially with monochloramine, whereas compounds with electron donating group (EDG) showed tendency to react with dichloramine to form NDMA. When the selected amines were present in NOM solutions, NDMA formation increased for compounds with EWG while decreased for compounds with EDG. This impact was attributed to the competitions between NOM and amines for chloramine species. The results provided additional information to the commonly accepted mechanism for NDMA formation including chloramine species reacting with tertiary amines and the role of the leaving group on overall NDMA conversion. (C) 2012 Elsevier Ltd. All rights reserved