Tryg Lundquist

Algae grown on dairy and municipal wastewater for simultaneous nutrient removal and lipid production for biofuel feedstock.

Algae grown on wastewater media are a potential source of low-cost lipids for production of liquid biofuels. This study investigated lipid productivity and nutrient removal by green algae grown during treatment of dairy farm and municipal wastewaters supplemented with CO2 . Dairy wastewater was treated outdoors in bench-scale batch cultures. The lipid content of the volatile solids peaked at Day 6, during exponential growth, and declined thereafter. Peak lipid content ranged from 14–29%, depending on wastewater concentration. Maximum lipid productivity also peaked at Day 6 of batch growth, with a volumetric productivity of 17 mg/day/L of reactor and an areal productivity of 2.8 g/ m2 /day , which would be equivalent to 11,000 L/ha/year (1,200 gal/acre/year) if sustained year round. After 12 days, ammonium and orthophosphate removals were 96 and >99% , respectively. Municipal wastewater was treated in semicontinuous indoor cultures with 2–4 day hydraulic residence times (HRTs). Maximum lipid productivity f...

Microalgal Biomass for Greenhouse Gas Reductions: Potential for Replacement of Fossil Fuels and Animal Feeds

Microalgal biomass production offers a number of advantages over conventional biomass production, including higher productivities, use of otherwise nonproductive land, reuse and recovery of waste nutrients, use of saline or brackish waters, and reuse of CO2 from power-plant flue gas or similar sources. Microalgal biomass production and utilization offers potential for greenhouse gas (GHG) avoidance by providing biofuel replacement of fossil fuels and carbon-neutral animal feeds. This paper presents an initial analysis of the potential for GHG avoidance using a proposed algal biomass production system coupled to recovery of flue-gas CO2 combined with waste sludge and/or animal manure utilization. A model is constructed around a 50-MW natural gas-fired electrical generation plant operating at 50% capacity as a semibase-load facility. This facility is projected to produce 216 million k⋅Wh/240-day season while releasing 30.3 million kg-C/season of GHG- CO2 . An algal system designed to capture 70% of flue-gas...

Algal biofuels from wastewater treatment high rate algal ponds.

This paper examines the potential of algae biofuel production in conjunction with wastewater treatment. Current technology for algal wastewater treatment uses facultative ponds, however, these ponds have low productivity (∼10 tonnes/ha.y), are not amenable to cultivating single algal species, require chemical flocculation or other expensive processes for algal harvest, and do not provide consistent nutrient removal. Shallow, paddlewheel-mixed high rate algal ponds (HRAPs) have much higher productivities (∼30 tonnes/ha.y) and promote bioflocculation settling which may provide low-cost algal harvest. Moreover, HRAP algae are carbon-limited and daytime addition of CO(2) has, under suitable climatic conditions, the potential to double production (to ∼60 tonnes/ha.y), improve bioflocculation algal harvest, and enhance wastewater nutrient removal. Algae biofuels (e.g. biogas, ethanol, biodiesel and crude bio-oil), could be produced from the algae harvested from wastewater HRAPs, The wastewater treatment function would cover the capital and operation costs of algal production, with biofuel and recovered nutrient fertilizer being by-products. Greenhouse gas abatement results from both the production of the biofuels and the savings in energy consumption compared to electromechanical treatment processes. However, to achieve these benefits, further research is required, particularly the large-scale demonstration of wastewater treatment HRAP algal production and harvest.

Wastewater Treatment and Algal Biofuel Production

Promoting algal production in wastewater treatment high rate algal ponds (HRAPs) by CO2 addition enables cost effective near tertiary-level wastewater treatment to be achieved and the harvested algal biomass by-product can be used for biofuel production. Naturally occurring algae thrive on wastewater providing the oxygen for aerobic bacteria to break down the waste to ammonia, phosphate and CO2 which are then assimilated into new algal biomass. Low C:N ratios in wastewater mean that additional CO2 added to HRAP will enable all the wastewater N to be assimilated into algal biomass. CO2 may be easily obtained at the treatment plant as exhaust gas from biogas power generation. CO2 addition to wastewater treatment HRAPs has a further benefit in enhancing bioflocculation of the algal-bacterial biomass to enable low-cost harvest by gravity settling. Although there are several options to convert harvested algal biomass to biofuel, processes that use the entire biomass with little or no dewatering are preferable, and for wastewater treatment plants, anaerobic digestion of the algal biomass along with settled primary sludge is the most easily implemented and economic technology. Since the capital and operation costs of wastewater treatment HRAP are covered by their wastewater treatment role, they provide a cost-effective, even if niche, opportunity for algal biofuel production that could be of great value to the local community. Moreover, GHG abatement and nutrient fertilizer recovery provide additional environmental and financial incentives. Upgrading existing wastewater treatment facultative ponds (used world-over for secondary-level wastewater treatment) to tertiary treatment HRAPs provides an avenue to refine operation and performance issues of these ponds at large(hectare)-scale, for future application to standalone algal biofuel systems.

Life cycle GHG emissions from microalgal biodiesel--a CA-GREET model.

A life cycle assessment (LCA) focused on greenhouse gas (GHG) emissions from the production of microalgal biodiesel was carried out based on a detailed engineering and economic analysis. This LCA applies the methodology of the California Low Carbon Fuel Standard (CA LCFS) and uses life cycle inventory (LCI) data for process inputs, based on the California-Modified Greenhouse Gases, Regulated Emissions, and Energy use in Transportation (CA GREET) model. Based on detailed mass and energy balances, calculated GHG emissions from this algal biodiesel system are 70% lower than those of conventional diesel fuel, meeting the minimum 50% GHG reduction requirements under the EPA RFS2 and 60% for the European Union Renewable Energy Directive. This LCA study provides a guide to the research and development objectives that must be achieved to meet both economic and environmental goals for microalgae biodiesel production.

Wastewater Treatment Pond Algal Production for Biofuel

Wastewater treatment high rate algal ponds fertilised with CO2 (HRAP + C system) provide a niche opportunity for algal biofuel production in combination with energy-efficient and cost-effective tertiary-level wastewater treatment. Wastewaters are excellent media (water, nutrients, alkalinity buffering) for the growth of naturally occurring algae that could be harvested by bioflocculation and low-cost gravity settling, especially when fertilised with CO2 obtained from biogas produced and used for power generation at the treatment plant. The harvested algal biomass is converted to biofuels, preferably by processes that use the entire biomass with little or no dewatering. Anaerobic digestion of the algal biomass along with settled primary sludge is the most readily available and economic technology. The wastewater treatment function can essentially cover the entire capital and operation costs of biofuel production. Additional environmental and financial incentives are due to GHG abatement and nutrient fertiliser recovery. Since wastewater treatment systems using facultative ponds are already a widely used technology for secondary-level wastewater treatment, upgrading these ponds provides an opportunity to develop and refine algal production and harvest from HRAP systems and algal biofuel conversion technologies. The HRAP + C system can produce biogas for power generation at essentially no additional cost to that incurred for wastewater treatment alone. Additional research, in particular, on selection and cultivation of superior algal strains, grazer control and cost-effective algal harvest is still required before widespread adoption of this technology is possible.

Integral microalgae-bacteria model (BIO_ALGAE): application to wastewater high rate algal ponds

An integral mechanistic model describing the complex interactions in mixed algal-bacterial systems was developed. The model includes crucial physical, chemical and biokinetic processes of microalgae as well as bacteria in wastewater. Carbon-limited microalgae and autotrophic bacteria growth, light attenuation, photorespiration, temperature and pH dependency are some of the new features included. The model named BIO_ALGAE was built using the general formulation and structure of activated sludge models (ASM), and it was implemented in COMSOL Multiphysics™ platform. Calibration and validation were conducted with experimental data from two identical pilot HRAPs receiving real wastewater. The model was able to simulate the dynamics of different components in the ponds, and to predict the relative proportion of microalgae (58-68% in average of total suspended solids (TSS) and bacteria (30-20% in average of TSS). Microalgae growth resulted strongly influenced by the light factor fL(I), decreasing microalgae concentrations from 40 to 60%. Furthermore, reducing the influent organic matter concentration of 50% and 70%, model predictions indicated that microalgae production increased from (8.7gTSSm-2d-1 to 13.5gTSSm-2d-1) due to the new distribution of particulate components. The proposed model could be an efficient tool for industry to predict the production of microalgae, as well as to design and optimize HRAPs.

Validation of mobile in situ measurements of dairy husbandry emissions by fusion of airborne/surface remote sensing with seasonal context from the Chino Dairy Complex

Mobile in situ concentration and meteorology data were collected for the Chino Dairy Complex in the Los Angeles Basin by AMOG (AutoMObile trace Gas) Surveyor on 25 June 2015 to characterize husbandry emissions in the near and far field in convoy mode with MISTIR (Mobile Infrared Sensor for Tactical Incident Response), a mobile upwards-looking, column remote sensing spectrometer. MISTIR reference flux validated AMOG plume inversions at different information levels including multiple gases, GoogleEarth imagery, and airborne trace gas remote sensing data. Long-term (9-yr.) Infrared Atmospheric Sounding Interferometer satellite data provided spatial and trace gas temporal context. For the Chino dairies, MISTIR-AMOG ammonia (NH3) agreement was within 5% (15.7 versus 14.9 Gg yr-1, respectively) using all information. Methane (CH4) emissions were 30 Gg yr-1 for a 45,200 herd size, indicating that Chino emission factors are greater than previously reported. Single dairy inversions were much less successful. AMOG-MISTIR agreement was 57% due to wind heterogeneity from downwind structures in these near-field measurements and emissions unsteadiness. AMOG CH4, NH3, and CO2 emissions were 91, 209, and 8200 Mg yr-1, implying 2480, 1870, and 1720 head using published emission factors. Plumes fingerprinting identified likely sources including manure storage, cowsheds, and a structure with likely natural gas combustion. NH3 downwind of Chino showed a seasonal variation of a factor of ten, three times larger than literature suggests. Chino husbandry practices and trends in herd size and production were reviewed and unlikely to add seasonality. Higher emission seasonality was proposed as legacy soil emissions, the results of a century of husbandry, supported by airborne remote sensing data showing widespread emissions from neighborhoods that were dairies 15 years prior, and AMOG and MISTIR observations. Seasonal variations provide insights into the implications of global climate change and must be considered when comparing surveys from different seasons.