Engineering Commons^™

Nutrient Removal In Microalgae Raceway Ponds And Nitrification Modeling, Esmeralda Diego

Master's Theses

This thesis explores the treatment of municipal wastewater using pilot-scale raceway ponds and looks specifically at the capability of the raceways in removing BOD and nitrogen. Nine 33 square-meter algal raceway ponds were used to conduct research at the San Luis Obispo Water Resources Recovery Facility. Main objectives of this study were to increase the removal of total ammonia nitrogen (NH₃-N plus NH₄⁺-N) from municipal wastewater through increased assimilation and nitrification. Raceway ponds with CO₂ addition were operated in series with an intermediate settling step and a total hydraulic retention time (HRT) of 4 …

Photobioreactor Design For Improved Energy Efficiency Of Microalgae Production, Alexander Burns

Master's Theses

ABSTRACT

Photobioreactor Design for Improved Energy Efficiency of Microalgae Production

Alexander Burns

The objective of this research was to investigate a new photobioreactor (PBR) design for microalgae production that retains the typical advantages of existing tubular PBRs while reducing power consumption by providing simultaneous culture circulation and gas exchange with airlift alone and no centrifugal recirculating pump. Traditional tubular PBR designs feature a compressed air supply and a centrifugal pump for culture circulation and gas exchange. Circulation and gas exchange in a closed-system PBR is necessary to keep the algae suspended and to provide sufficient mass transfer (mainly for the …

The Effect Of Pretreatment Methods On Methane Yield And Nutrient Solubilization During Anaerobic Digestion Of Microalgae, Alexander Scott Hill

Master's Theses

Microalgal biomass is a candidate feedstock for biofuel production. To improve the sustainability of algae biofuel production, following biofuel recovery, the biomass nutrients should be recycled for additional algae growth. Anaerobic digestion of algae or oil-extracted algae is a means of recovering carbon and other nutrients, while offsetting algae production electricity demand. The major limiting factor in microalgae digestion is the low biodegradability of the cell walls. In the present study, various pretreatment technologies were tested at bench scale for their ability to improve raw, non-lipid-extracted algae biodegradability, which was assessed in terms of methane yield, volatile solids destruction, and …

Nutrient Removal Using Microalgae In Wastewater-Fed High Rate Ponds, Matthew N. Rodrigues

Master's Theses

This thesis discusses the mechanisms associated with the removal of organic matter, nitrogen and phosphorus in wastewater-fed high rate algae ponds (HRAP) designed to operate as triplicates. Research was conducted at the San Luis Obispo Water Reclamation Facility (SLOWRF) as a pilot-scale study of nine 30-square meter ponds one foot in depth. During period of study, triplicates were operated at hydraulic retention times (HRT) of 4, 3 or 2-days. Main objectives for the study were to determine minimum HRTs required to achieve secondary and tertiary treatment. Experimental conditions such as CO₂ supplementation, nighttime aeration and operation of ponds in …

Seawater/Wastewater Production Of Microalgae-Based Biofuels In Closed Loop Tubular Photobioreactors, Joshua Bradley Lowrey

Master's Theses

The push for alternatives to petroleum fuels has forced researchers to look for highly productive, renewable, non-food resources. The advantages of using microalgae instead of traditional oil crops for biofuel production include high oil yields, rapid reproductive rates, and versatile growing requirements. In order to reduce the cost of producing microalgae based biofuels, wastewater has been used as a nutrient source instead of specialized plant nutrients. The purpose of this study was to compare the relative effectiveness of different combinations of microalgae strain and dairy wastewater for increasing biomass. The methods for monitoring growth included optical density, cell counting, biomass …

Anaerobic Co-Digestion Of Microalgae With Food Waste And Wastewater Sludge, Ruth E. Spierling

Master's Theses

This research sought to optimize anaerobic co-digestion of microalgae biomass harvested from a wastewater treatment pond facility with locally-available wastes. The goal was to produce high methane yields and stable digestion without the need for supplemental alkalinity addition. A key research question was if algae digestion could be improved via the synergistic effects of co-digestion. Cell disruption to increase digestibility was not pursued due to its relatively high mechanical complexity and high energy use. For the wastewater treatment ponds studied, the most practical co-substrates identified were municipal wastewater sludge and food waste (sorted organic municipal waste). Although wastewater sludge does …

Temperature Influence And Heat Management Requirements Of Microalgae Cultivation In Photobioreactors, Thomas Hagen Mehlitz

Master's Theses

Microalgae are considered one of the most promising feedstocks for biofuel production for the future. The most efficient way to produce vast amounts of algal biomass is the use of closed tubular photobioreactors (PBR). The heat requirement for a given system is a major concern since the best algae growth rates are obtained between 25-30 °C, depending on the specific strain. A procedure to determine temperature influence on algal growth rates was developed for a lab-scale PBR system using the species Chlorella. A maximum growth rate of 1.44 doublings per day at 29 °C (optimal temperature) was determined. In addition, …