Craig Frear

Potential application of Alcaligenes faecalis strain No. 4 in mitigating ammonia emissions from dairy wastewater.

This research examined the potential mitigation of NH3 emissions from dairy manure via an enhanced aerobic bio-treatment with bacterium Alcaligenes faecalis strain No. 4. The studies were conducted in aerated batch reactors using air and pure oxygen. Aeration with air and oxygen removed approximately 40% and 100% total ammoniacal nitrogen (TAN), respectively. Intermittent oxygenation (every 2 or 4 h) reduced oxygen consumption by 95%, while attaining nearly identical TAN removal to continuous aeration. The results revealed that adequate oxygen supply and supplementing dairy wastewater with carbon are essential for this bioprocess. Based on the nitrogen mass balance, only 4% of TAN was released as NH3 gas, while the majority was retained in either the microbial biomass (58%) or converted to nitrogen gas (36%). The mass balance results reveal high potential for environmentally friendly bio-treatment of dairy wastewater using A. faecalis strain No. 4 with respect to NH3 emissions.

Consolidated bioprocessing of microalgal biomass to carboxylates by a mixed culture of cow rumen bacteria using anaerobic sequencing batch reactor (ASBR).

This study employed mixed-culture consolidated bioprocessing (CBP) to digest microalgal biomass in an anaerobic sequencing batch reactor (ASBR). The primary objectives are to evaluate the impact of hydraulic residence time (HRT) on the productivity of carboxylic acids and to characterize the bacterial community. HRT affects the production rate and patterns of carboxylic acids. For the 5-L laboratory-scale fermentation, a 12-day HRT was selected because it offered the highest productivity of carboxylic acids and it synthesized longer chains. The variability of the bacterial community increased with longer HRT (R2=0.85). In the 5-L laboratory-scale fermentor, the most common phyla were Firmicutes (58.3%), Bacteroidetes (27.4%), and Proteobacteria (11.9%). The dominant bacterial classes were Clostridia (29.8%), Bacteroidia (27.4%), Tissierella (26.2%), and Betaproteobacteria (8.9%).

Impact of Anaerobic Digestion of Liquid Dairy Manure on Ammonia Volatilization Process

Abstract. The goal of this study was to determine the effect of anaerobic digestion (AD) on the mechanism of ammonia volatilization from liquid dairy manure, in storage or treatment lagoon, prior to land application. Physical-chemical properties of liquid dairy manure, which may affect ammonia volatilization process, were determined before and after AD. The properties of interest included: particle size distribution (PSD), total solids (TS), volatile solids (VS), viscosity, pH, total ammoniacal nitrogen (TAN), and ionic strength (IS). The overall mass transfer coefficient of ammonia (KoL) and the NH3 fraction of TAN (I²) for the undigested (UD) and AD manures were then experimentally determined in a laboratory convective emission chamber (CEC) at a constant wind speed of 1.5 m s-1 and fixed air temperature of 25 °C at liquid manure temperatures of 15, 25, and 35 °C. The PSD indicated non-normal left skewed distribution for both AD and UD manures particles, suggestive of heavier concentrations of particles towards the lower particle size range. The volume median diameters (VMD) for solids from UD and AD were not significantly different (p= 0.65), but the geometric standard deviations (GSD) were significantly different (p = 0.001), indicating slightly larger particles but more widely distributed solids in UD than AD manure. Results also indicated significantly higher pH, TAN, ionic strength (IS) and viscosity in AD manure. The KoL and I² for AD manure determined under identical conditions (air temperature, liquid temperature, and airflow) were significantly higher (p > 0.05) than for UD manure. Overall, these findings suggest that AD of dairy manure significantly increased initial ammonia volatilization potential from liquid dairy manure; with the largest increase (~62%) emanating from increased ammonium dissociation. The initial flux of ammonia, during the experiment period, was ~84% more from AD than in UD dairy manure.

Enhance volatile fatty acid (VFA) and bio-methane productivity by pretreatment of lawn grass

Abstract. Lawn grass is a huge potential source of bio-fuel production because there are 27.6 million acres of turf grass in U.S., and 21 million acres in home lawns. Anaerobic digestion (AD) of lawn grass is an effective way to produce bio-methane, and to reduce the strain on the environment from greenhouse gases and overcrowded landfills. The potential bioconversion of carbohydrates in this potential resource, however, is limited by the associated cellulose and hemicellulose within the grass fiber. These constitutes must be broken down into their corresponding monomers (sugars), so that microorganisms can efficiently utilize them. To establish an efficient AD system, three pretreatments including ozone, soaking aqueous ammonia (SAA), and a combination of ozone and soaking aqueous ammonia (OSAA) optimized in our group were investigated to enhance volatile fatty acid (VFA) and bio-methane productivity of Kentucky bluegrass (Poa pratensis L.). Sodium 2-bromoethanesulfonate was used to inhibit methanogenic bacteria for studying VFA production. The results showed that the ammonia pretreatment was the most effective way to accelerate VFA and bio- methane production rate of kentucky bluegrass. These results would suggest that aqueous ammonia reused from our developed nutrient recovery system will reduce the cost of pretreatment.