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The combination of MTSP and TSPPC, Multiple Traveling Salesman Problem with precedence constraints, leads to the difficulty of solving problem in practical such as industrial production, logistics transportation and semiconductors. Several methods, including heuristic method, were introduced to solve problems related to MTSP and TSPPC. By redefining the optimal-solution searching process of Dynamic Tabu Artificial Bee Colony algorithm, MTSPPC problem could be solved. The results illustrated that the redefined-optimal-solution-searching-process-based Dynamic Tabu Artificial Bee Colony algorithm is suitable for solving MTSPPC problem.

A fermentative enrichment culture (designated DHM-1) was developed that is capable of cometabolically biotransforming high concentrations of chloroform (CF) to nontoxic end products. Two Pantoea spp. were isolated from DHM-1 that also possess this dechlorination capability. Following acclimation to increasing levels of CF, corn syrup-grown DHM-1 was able to transform over 500 mg/liter CF in the presence of vitamin B 12 (approximately 3% of CF on a molar basis) at a rate as high as 22 mg/liter/day in a mineral salts medium. CO, CO 2 , and organic acids were the predominant biodegradation products, suggesting that hydrolytic reactions predominate during CF transformation. DHM-1 was capable of growing on corn syrup in the presence of high concentrations of CF (as may be present near contaminant source zones in groundwater), which makes it a promising culture for bioaugmentation. Strains DHM-1B and DHM-1T transform CF at rates similar to that of the DHM-1 enrichment culture. The ability of these strains to grow in the presence of high concentrations of CF appears to be related to alteration of membrane fluidity or homeoviscous and homeophasic adaptation.

A pilot scale investigation was undertaken at the Allegheny County Sanitary Authority (ALCOSAN) for approximately 12 months to evaluate the feasibility of using cross-flow microfiltration for the treatment of primary sewage effluent simulating combined and sanitary sewer overflows. Ceramic membranes of various pores sizes (0.05–1.4 μm) were tested to understand the impact of cross-flow velocity, transmembrane pressure, and feed suspended solids on permeate water quality and permeate flux rate. A 0.2 μm membrane operated with a 1.8 m∕s cross-flow velocity, a transmembrane pressure below 2.1 bar and a backpulse frequency of 60 s showed the best performance among the conditions evaluated in this study. The 0.2 μm membrane consistently met water quality objectives for fecal coliforms, E Coli, enterococci, BOD5 , and suspended solids independent of the feed concentration, suggesting that direct discharge to surface water may be feasible. Feed suspended solids concentration and temperature influenced membrane p...

A fermentative enrichment culture (designated DHM-1) that grows on corn syrup was evaluated for its ability to cometabolically biodegrade high concentrations of chloroform (CF), carbon tetrachloride (CT), and trichlorofluoromethane (CFC-11). When provided with corn syrup and vitamin B12 (0.03 mol B12 per mol CF), DHM-1 grew and biodegraded up to 2,000 mg/L of CF in 180 days, with only minor transient accumulation of dichloromethane and chloromethane. CT (15 mg/L) and CFC-11 (25 mg/L) were also biodegraded without significant accumulation of halomethane daughter products. The rate of CF biodegradation followed a Michaelis-Menten-like pattern with respect to the B12 concentration; one-half the maximum rate (66 mg CF/L/d) occurred at 0.005 mol B12 per mol CF. DHM-1 was able to biodegrade 500 mg/L of CF at an inoculum level as low as 10−8 mg protein/L. The highest rate of CF biodegradation occurred at pH 7.7; activity decreased substantially below pH 6.0. DHM-1 biodegraded mixtures of CT, CFC-11, and CF, although CFC-11 inhibited CF biodegradation. Evidence for compete defluorination of CFC-11 was obtained based on a fluoride mass balance. Overall, the results suggest that DHM-1 may be effective for bioaugmentation in source zones contaminated with thousands of milligrams per liter of CF and tens of milligrams per liter of CT and CFC-11.

Intensively cultured fish stock when fed protein-rich feeds typically excrete high concentrations of total ammoniacal-nitrogen (TAN) into the water column which can have adverse effects on productivity, and upon the environment when aquaculture water is discharged. An immobilized culture of nitrifying bacteria isolated from prawn pond water and known to effectively remove TAN from saline water was tested for its ability to remove TAN from freshwater. The culture was readily adaptable to non-saline conditions and maintained TAN at less than 0.25 mg l−1, even with a daily addition of 3.2 to 4.2 mg TAN l−1 per d. The use of the immobilized culture of nitrifying bacteria represents an innovative and economical in situ treatment technology for removal of TAN in both saline and freshwater.

This study focused on irreversible fouling during microfiltration of primary and secondary effluents from municipal wastewater treatment plants. Flow resistances were calculated from the sum of clean membrane resistances, resultant cake layer resistances, and consequent irreversible fouling resistances. Results from a dead-end cell experimental system showed that the accumulated cake resistance was dominating for microfiltration of primary/secondary effluents. Suspended solids in the primary and secondary effluents had a similar compressibility index, n, with a value of approximately 0.5, indicating that they were moderately compressible particles. The value of irreversible resistance is dependent on the intensity of membrane cleaning; however, for a given membrane cleaning strategy, this value steadily increased and reached a maximum after approximately 6 cycles of filtration and cleaning. This study provided an explanation for the significant drop of throughput flux in the early application of membrane processes, and a plateau flux approached correspondingly.