Date of Award

12-2014

Degree Name

MS in Civil and Environmental Engineering

Department

Civil and Environmental Engineering

Advisor

Tryg Lundquist

Abstract

Growth Media and Lipid Determination Comparison

of High Rate Algae Ponds

Eric Alexander Nicolai

The feasibility of algal biofuel production relies on the use of a non-potable water source. Municipal wastewater is nutrient-rich and a cost effective option as a growth media in algae ponds. However, this resource may be too valuable for algal biomass production, as reclaimed wastewater is needed for surface irrigation and groundwater recharge. This thesis compares the performance of 4.2 m2 high rate algal raceway ponds (HRAPs) to 33 m2 HRAPs grown on primary settled wastewater during a media recycling study and a growth media comparison study using wastewater and reclaimed water. The comparative metrics of performance for this study included: pond productivity, settling efficiency, and nutrient removal. This thesis also discusses the variability of algal lipid content from wastewater ponds using three different lipid determination methods. Six 4.2-m2, 0.3 m deep HRAPs were compared to nine 33-m2 HRAPs located at the San Luis Obispo Water Resource Recovery Facility (SLOWRRF). During the media recycling study, the first round of growth (Round 1) included ponds operating at 2-day and 3-day hydraulic retention times (HRTs) for both pond sizes. The pond arrangements for the second round of growth (Round 2) were the same with the exception of no 2-day HRT for the 33-m2 pond set. Net biomass productivity in the 4.2-m2 ponds under predicted the productivity of the 33-m2 ponds. Settling efficiency was comparable between the different rounds of growth for both pond sizes. Total soluble nitrogen removal was predicted using 4.2-m2 ponds. Of the three lipid determination methods, the fatty acid methyl esters (FAMEs) quantification was the most precise between replicates. However, this method determined the lowest lipid content because it quantifies a better representative lipid content by excluding other constituents not relevant to biofuel production.

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