Time filter

Source Type

Lake Oswego, OR, United States

We describe a simple method for tracking the course of microbial degradation of polysaccharide-rich feedstocks. The method involves determining total polysaccharides present in the feedstock, measured in glucose equivalents, relative to the fractional component of polysaccharides exhibiting 2,3-dinitrosalycylic acid aldehyde activity. The ratio of total polysaccharide to aldehyde activity, defined as the end-point fragmentation (EPF) index, is then calculated and tracked as it shifts as microbial degradation of polysaccharide-rich feedstock progresses. While degradation occurs, the EPF index falls. It bottoms out at an asymptotic limit marking the point in time where further degradation of the polysaccharide-rich feedstock has ceased. The EPF index can be used to follow the progressive breakdown of composting polysaccharide-rich waste. It may also have applicability as a means of tracking the turnover of polysaccharides in other complex environments including soil, sediments, wetlands, and peat bogs. © 2010 Springer Science+Business Media, LLC. Source

Green T.R.,TGA LLC | Popa R.,Portland State University
Applied Biochemistry and Biotechnology

Black soldier fly (BSF) larvae (Hermetia illucens), feeding on leachate from decaying vegetable and food scrap waste, increase ammonia (NH 4 +) concentration five- to sixfold relative to leachate unprocessed by larvae. NH 4 + in larva-processed leachate reached levels as high as ∼100 mM. Most of this NH 4 + appears to have come from organic nitrogen within the frass produced by the larvae as they fed on leachate. In nitrate-enriched solutions, BSF larvae also facilitate dissimilatory nitrate reduction to ammonia. The markedly higher concentration of NH 4 + recovered in leachates processed with BSF larvae and concomitant diversion of nutrients into insect biomass (itself a valuable feedstock) indicate that the use of BSF larvae in processing leachate of decaying organic waste could be advantageous in offsetting capital and environmental costs incurred in composting. © Springer Science+Business Media, LLC 2012. Source

Green T.R.,TGA LLC | Popa R.,Portland State University
Journal of Polymers and the Environment

We describe a simple method for measuring cellulose in soil. We used this method to measure the recovery of shredded office paper and pure medium fiber cellulose added to a Helvetia silt loam clay soil. This method consists of solvating cellulose from soil with 77% H 2SO 4 and analysis of the cellulose recovered by the phenol-sulfuric acid carbohydrate assay. Unlike previous related methods the modifications we propose allow good recovery of cellulose (~99%) and eliminate the need to autoclave the samples. We verified this method on soil spiked with up to 12% cellulose and found a good linear relationship between the amounts of cellulose added relative to that recovered. With proper fragmentation and dilution of the acid-treated soil samples, higher concentrations can be easily measured. We propose this technique as a robust and high throughput means to monitor the degradation of cellulose in paper spiked soil. © 2010 Springer Science+Business Media, LLC. Source

Popa R.,Portland State University | Green T.R.,TGA LLC
Journal of Economic Entomology

A large number of biodegradable byproducts including alcohols, soluble saccharides, volatile organic acids, and amines accumulate in the liquid fraction (leachate) produced as vegetal and food scrap waste decomposes. Untreated leachate, because it is rich in nutrients and organic byproducts, has a high chemical oxygen demand and is normally cleared of soluble organic byproducts by mineralization before its discharge into waterways. Mineralizing leachates using chemical and microbial biotechnologies is, however, a lengthy and costly process. We report here that the larvae of the black soldier fly Hermetia illucens (L.) (Diptera: Stratiomyidae), an insect rich in protein and lipids, and having significant commercial value, while feeding and growing off of compost leachate, lowers its chemical oxygen demand relative to that of leachate unexposed to larvae, neutralizes its acidity, and clears it of volatile organic acids, amines, and alcohols. These observations demonstrate that black soldier fly larvae could be used to help offset the cost and clean up of organic solutes in leachate waste streams while recycling carbon, nitrogen, and phosphate into usable and commercially valuable biomass. © 2012 Entomological Society of America. Source

Discover hidden collaborations