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Full-Text Articles in Environmental Engineering

Field Emissions Of (Hydro)Chlorofluorocarbons And Methane From A California Landfill, Alexander H. Sohn Dec 2016

Field Emissions Of (Hydro)Chlorofluorocarbons And Methane From A California Landfill, Alexander H. Sohn

Master's Theses

A comprehensive field investigation was conducted at Potrero Hills Landfill (PHL) located in Suisun City, California to quantify emissions of twelve (hydro)chlorofluorocarbons (i.e. F-gases). The specific target constituents for this study included CFC-11, CFC-12, CFC-113, CFC-114, HCFC-21, HCFC-22, HCFC-141b, HCFC-142b, HCFC-151a, HFC-134a, HFC-152a, and HFC-245fa. The majority of the F-gas emission studies have been conducted outside of the United States and very limited field landfill emission data are available in the United States. Because of historical usage of blowing agents in insulation foams including CFC-11, HCFC-142b, HFC-134a, and HFC-245fa, models reported in literature predicted high F-gas emissions from a landfill …


Regrowth Of Chlorella Sorokiniana On Recycled Media With Replenished Nutrients, William H. Spence Jun 2016

Regrowth Of Chlorella Sorokiniana On Recycled Media With Replenished Nutrients, William H. Spence

Master's Theses

Growth media recycling during algae cultivation is necessary to increase the efficiency and reduce the cost of biofuel production from algae feedstocks. Without recycling media, the cost of algae based biofuel production would be prohibitively high and large scale algae based biofuel production would not be economically viable. The ratio of media recycled to media wasted assumed for algae farms is generally calculated to maintain salt concentrations below growth inhibitory levels, ignoring the influence of secondary metabolites which might decrease productivity. Secondary metabolites, which include allelopathic or auto-inhibitory biological contaminants, might lead to the accumulation of growth-inhibiting compounds in recycled …


Ncma Groundwater Model Using Usgs Modflow-2005/Pest, Brian Matthew Wallace Jun 2016

Ncma Groundwater Model Using Usgs Modflow-2005/Pest, Brian Matthew Wallace

Master's Theses

A numerical model for the NCMA aquifer complex is presented. The objective of the study is to develop a numerical groundwater model for the NCMA aquifer system to enhance the understanding of subsurface groundwater flow. Infiltration, streamflow, pumping, and return flows are implemented to characterize the aquifer complex over time. The numerical model is calibrated to municipal and monitoring well data, average monthly water balances, and hydraulic contours. Transient aquifer inflows and outflows are assessed in the results of the study and are compared to balance terms from previous studies. The 2007 Todd Engineers Study subsurface inflows and outflows generate …


Seasonal And Dilution Rate Impacts On Nannochloropsis Oceanica Productivity In Algae Raceway Ponds, Garrett Dameron Murawsky Mar 2016

Seasonal And Dilution Rate Impacts On Nannochloropsis Oceanica Productivity In Algae Raceway Ponds, Garrett Dameron Murawsky

Master's Theses

Biomass growth of the alga Nannochloropsis oceanica, cultivated outdoors in six pilot-scale raceway ponds, was monitored over the course of 1.5 years, at two different dilution regimes each season, to establish the effects on algal biomass productivity and concentration of dilution rate, pond water temperature, and solar radiation. The 4.5-m2 ponds were located in a mild, mid-latitude, coastal region (central California). Experimental conditions were operated in duplicates or triplicates with a consistent artificial seawater medium, pond depth, pH range, paddle wheel mixing speed, and replete nutrient conditions for the duration of the study. Two cultivation regimes were used …