Venting Strategy Research Articles

Biological treatment of a soil contaminated with diesel fuel using periodically operated slurry and Solid Phase Reactors

A silty clay loam contaminated with diesel fuel was treated in the laboratory using periodically operated slurry and solid phase bioreactors. Soil Slurry-Sequencing Batch Reactors (SS-SBRs) were operated with a 40% solids concentrations (w/v) to determine the effect of hydraulic residence time and volumetric replacement strategy on performance. Solid Phase-Sequencing Batch Reactors (SP-SBRs) were operated with the same silty clay loam artificially contaminated with diesel fuel. Different periodic aeration strategies were investigated in the SP-SBRs in an attempt to minimize volatile losses without sacrificing overall removal efficiency.Results showed that a day 10 HRT in the SS-SBRs was optimal for the soil tested. The rate and extent of diesel fuel removal was increased by providing a higher concentration of diesel fuel at the beginning of the SBR cycle, indicating that removal rates are not zero-order. The findings also showed that a properly operated periodic venting strategy produced high overall removal efficiencies with considerably less volatilization than continuous aeration.

Biological treatment of a soil contaminated with diesel fuel using periodically operated slurry and solid phase reactors

A silty clay loam contaminated with diesel fuel was treated in the laboratory using periodically operated slurry and solid phase bioreactors. Soil Slurry-Sequencing Batch Reactors (SS-SBRs) were operated with a 40% solids concentrations (w/v) to determine the effect of hydraulic residence time and volumetric replacement strategy on performance. Solid Phase-Sequencing Batch Reactors (SP-SBRs) were operated with the same silty clay loam artificially contaminated with diesel fuel. Different periodic aeration strategies were investigated in the SP-SBRs in an attempt to minimize volatile losses without sacrificing overall removal efficiency. Results showed that a day 10 HRT in the SS-SBRs was optimal for the soil tested. The rate and extent of diesel fuel removal was increased by providing a higher concentration of diesel fuel at the beginning of the SBR cycle, indicating that removal rates are not zero-order. The findings also showed that a properly operated periodic venting strategy produced high overall removal efficiencies with considerably less volatilization than continuous aeration.

Runaway reaction hazard and venting of a cyanide reaction

The runaway reaction hazard of a cyanide reaction initiated by an amine and caustic has been studied extensively and a venting strategy formulated from the data. The relief size necessary to safely relieved such a reaction has been calculated using thermal runaway data for a number of different situations, allowing for two-phase flow.

Marine policy

The runaway reaction hazard of a cyanide reaction initiated by an amine and caustic has been studied extensively and a venting strategy formulated from the data. The relief size necessary to safely relieved such a reaction has been calculated using thermal runaway data for a number of different situations, allowing for two-phase flow.

Risk reduction by filtered venting in PWR large dry-containments

The potential risk reduction associated with a Filtered-Vented Containment System is evaluated. A low-volume venting strategy has been considered and data referring to the Zion power plant, along with the results of the Zion Probabilistic Safety Study, have been used. An estimate of the reduction factor is first made for a single core melt accident sequence whose containment failure mode is late overpressure. The result, interpreted as a reduction factor applicable to the release category associated with containment late overpressure is then used for the estimation of the overall risk reduction factor. In particular, the case of internal and external risk for the Zion power plant are considered. Because the contribution from seismic events dominates the overall risk, the importance of different assumptions for seismic fragility is also assessed. Finally an uncertainty analysis of the risk reduction factor for a single accident sequence is performed. An estimate is also obtained on the level of confidence with which certain required values of risk reduction can be achieved.

Venting for the removal of hydrocarbon vapors from gasoline contaminated soil

Abstract The utilization of a venting strategy to remove gasoline vapors from contaminated soil strata was investigated in this exper‐ment. A contained gasoline “leak”; was created in a large outdoor facility which simulated soil strata and a static water table. An air flow was established, and vapor samples taken before, during, and after venting were checked for hydrocarbon content. The effluent air was regularly sampled for carbon dioxide and total hydrocarbons. Carbon dioxide data were used to estimate the amount of microbiological activity, and total hydrocarbon data were used to calculate the total amount of gasoline removed by venting. Hydrocarbon condensates from the effluent air were collected periodically and the compositions of these condensates were compared to the compositions of the starting gasoline and the residual that remained in the soil. During 11 days of continuous venting, 57% of the original 75 gallons of gasoline was removed by venting. Carbon dioxide production indicates that micr...