Pretreatment of \u3cem\u3eScenedesmus\u3c/em\u3e sp. Biomass as a Potential Anaerobic Digestion Substrate

Algal biomass can be a potential substrate for anaerobic digestion. However, raw algae cells show a resistance to biological degradation, resulting in a slower methane production rate. Varying thermal and chemical pretreatments of algal biomass were investigated in an attempt to increase soluble organic matter (SOM) yield, which would result in enhanced methane production during subsequent anaerobic digestion. Scenedesmus sp. was harvested using three different procedures: with flocculation, with flocculation and drying, and without flocculation or drying. For all pretreatments and algae types, fluorescence micrographs were obtained to visually confirm the degradation of the algal cell walls. A complete 2x3x4 factorial design was applied for the algal biomass pretreatment study, including two heating temperatures (50°C or 90°C), three heating durations (10, 30, or 60 min), and four NaOH concentrations (0%, 3%, 6%, or 12% g NaOH g-1 DW of algae). For algae cells with no flocculant addition, SOM yield increased by 15% with a moderate pretreatment of heating at 50°C in 3% NaOH for 60 min. For dried algae, the baseline SOM yield was higher than in the other algae, such that there was only a noticeable increase with the more severe pretreatments. For flocculated algae, the most severe pretreatment increased SOM yield by 17.2%, but overall the SOM increase was less than with fresh algae. Flocculation appears to inhibit cell wall disruption, but thermal chemical treatment can hydrolyze some flocculant polymers, which eases the flocculation and facilitates cell destruction

Evaluation of Foam Fractionation Column Scale-Up for Recovering Bovine Serum Albumin

Foam fractionation is an adsorptive-bubble separation method that, according to researchers, is a feasible technique for the separation and/or concentration of proteins. The foam fractionation of bovine serum albumin (BSA) in laboratory-scale foam fractionation columns (750 and 1250 mL) and the relationship between the two laboratory-scale columns and a pilot-scale column (5000 mL) were investigated. Recovery, enrichment, and performance factor values were experimentally determined with three different column volumes with varying pore sizes, gas superficial velocities, and, in the case of the 750 mL column, foam column height. As the pore size decreased, the amount of protein recovered from the dilute protein solution increased and the enrichment decreased. As the flow rate of the gas increased, the effect of the pore size decreased. For the three column volumes, the optimal column conditions were achieved with the largest pore size (145-174 μm) and an intermediate superficial gas velocity (7 mm/s). Increasing the foam column height increased the enrichment without sacrificing the recovery of the target protein. In the case of the largest pore size, the linear relationships between the recovery and the ratio of gas volume to initial liquid volume are parallel, such that the recovery in a pilot-scale column (5000 mL) can be predicted with the recovery found with a laboratory-scale column (750 or 1250 mL)

Effect of Stover Fraction on Glucose Production Using Enzymatic Hydrolysis

Corn stover was fractionated into three fractions: cobs, stalks, and leaves and husks. The fractions were dried and ground through a 2 mm screen. Samples of the three fractions and whole corn stover with and without NaOH pretreatment were subjected to enzymatic hydrolysis in order to determine the effect of fractionation on glucose production. The average amounts of glucose released after 60 h of hydrolysis from pretreated cobs, leaves and husks, stalks, and whole stover were 0.50, 0.36, 0.28, and 0.36 g/g dry biomass, respectively. The average amounts of glucose released after 60 h of hydrolysis from nonpretreated cobs, leaves and husks, stalks, and whole stover were 0.32, 0.23, 0.17, and 0.20 g/g dry biomass, respectively. Pretreatment resulted in an average increase of 60% in glucose production for all fractions and whole stover. The effect of stover fraction type on glucose production was significant with and without pretreatment. By collecting the fractions of the corn stover with the highest glucose potential (all the cobs and 74% of the leaves and husks) and leaving the remaining fraction (26% of the leaves and husks, and all the stalks) in the field for erosion control, the glucose potential of the collected biomass would increase by 21%. This could represent a decrease of up to 17% in the cost of ethanol production. This indicates that fractionation and collection of the biomass with the highest glucose potential may produce a higher quality feedstock for glucose production

Evaluation of Fourier Transform Infrared Spectroscopy Measurements of Glucose and Xylose in Biomass Hydrolyzate

Measurement of sugars using traditional spectroscopic (UV/Vis) assays or high performance liquid chromatography (HPLC) can be time consuming and expensive. Alternative methods for measuring sugars after enzymatic hydrolysis of biomass would be convenient for screening potential biomass feedstocks and pretreatment methods. Fourier transform infrared spectroscopy (FTIR) has been utilized for measuring composition of various aqueous solutions and is evaluated here as an alternative to UV/Vis and HPLC assays. Solutions of glucose and xylose with concentrations between 0 and 1.5% w/v (total sugar content between 0 and 3.0% w/v) were used to build calibration curves for all three methods. A validation set of 10 samples of varying concentrations of glucose and xylose (between 0 and 1.5% w/v) were used to quantify the performance of the three measurement techniques. The FTIR assay was able to predict the glucose and xylose concentration with a standard error of prediction (SEP) of 0.03% (w/v), lower than the SEP for the HPLC (~0.06%) and UV/Vis (~0.07%) assays. The FTIR assay was also able to accurately measure the sugar concentration of wheat stover (raw and pretreated with sodium hydroxide) after enzyme hydrolysis, although all three techniques produced similar results

Characterization of Dairy Milk House Waste Water in Kentucky

This study focuses on characterization of milk house waste water from eight different farms in Kentucky. The farms were separated into three groups based on the number of cows: small (20-30), medium (30-60), and large (over 60 cows). Samples were collected once a month from four farms and twice a month from the remainder. Samples were analyzed for chemical, biochemical, and microbiological characteristics. Results indicated a large and significant variation in the chemical and microbiological characteristics between the farms. Farm size had a significant effect on the nutrient content of the waste water. Though samples exhibited seasonal variation, there was no trend. Based on the results we will investigate the use of anaerobic-aerobic-anoxic-aerobic sequencing batch reactor (SBR) to treat milk house waste water on a pilot scale

Application of Recycled Media and Algae-Based Anaerobic Digestate in \u3cem\u3eScenedesmus\u3c/em\u3e Cultivation

To make large-algae cultivation systems sustainable, commercial fertilizer inputs should be minimized. One means of achieving this is to maximize the recycle of nutrients used in algae cultivation. In addition to recycling nutrient-containing water from algae harvesting and dewatering, after harvesting algal biomass can be used as a substrate for anaerobic digestion, which can then generate mineralized nutrients to be used for further cultivation. In this study, the effect of recycling media and using mineralized nutrients during Scenedesmus cultivation was investigated. The recycled media proved to be able to support cell growth with nutrient replenishment, and it could be recycled for cultivation up to four times. Algae biomass was subjected to anaerobic digestion, and the liquid digestate and the total digestate were tested as nutrient sources. The digestate was rich in ammonium ions and proved to be a sufficient replacement for urea. When both urea and ammonium ions were available in the media, the assimilation of urea by algal cells slowed down compared to the case where urea was the only nitrogen source

Biodiesel FAQ

Biodiesel and other alternative fuels continue to gain popularity as petroleum fuel prices rise and we become more concerned about our environment. Introduction of these fuels raises many questions about actually using them in current equipment. The purpose of this factsheet is to address some of the common questions asked by those considering the use of biodiesel in existing diesel equipment

Evaluation of Flocculation, Sedimentation, and Filtration for Dewatering of \u3cem\u3eScenedesmus\u3c/em\u3e Algae

Algae can be used as a feedstock for agricultural fertilizers, livestock and poultry feeds, anaerobic digestion, and biofuel production. For each end product, the requirements for moisture content (or solids content) vary, such that a desirable water removal strategy needs to be adaptable to varying levels of water removal. Flocculation, sedimentation, and filtration were evaluated as possible strategies for thickening and dewatering of algae. The goal of this study was to validate that algae cells treated by such means could be processed by vacuum belt filters and to determine the conditions under which the solids content could be increased to 5 to 25 wt%. The flocculation and sedimentation studies focused on conditions needed to thicken algae from a culture concentration range of 0.4 to 1 g L-1 to an end-product concentration range of 15 to 50 g L-1. Sedimentation rates of were measured with varying flocculant dosages (0 to 25 ppm) for various flocculants. The highest level of compaction was achieved with a synthetic cationic polymeric flocculant with higher molecular weight at a dosage of 15 ppm, which provided 16.3 mL of compacted solids (3.3 wt% solids). Subsequently, solids were successfully separated as a cake via gravity and vacuum filtration. The filtration studies focused on the conditions needed to filter flocculated algae slurry from a concentration range of 15 to 50 g L-1 to a product at a concentration range of 50 to 250 g L-1. Filtration rates of were measured on algae slurry treated with 10 to 15 ppm of a synthetic cationic polymeric flocculant. Processing parameters such as cake formation time, filtration rate, and mass throughput were evaluated against variables such as cake thickness, feed concentration, and processing time

Biodiesel Basics

Biodiesel is a renewable fuel for diesel engines. Biodiesel, defined by ASTM International (D6751), consists of longchain fatty acid alkyl esters and is made from renewable vegetable oils, recycled cooking oils, or animal fats. It can be used at full strength, but it is typically blended with petroleum diesel. A blend of 2 percent biodiesel and 98 percent diesel is referred to as B2. Other typical blends include B5, B10, and B20; pure biodiesel is sometimes referred to as B100. Biodiesel is safer for the environment and produces significantly less air pollution compared to petroleum diesel. Biodiesel can be produced locally and can be integrated into the existing petroleum infrastructure

Predicting the Cutting Time of Cottage Cheese Using Backscatter Measurements

An automated system for monitoring culture growth and determining coagulum cutting time is needed for cottage cheese manufacturing. A light backscatter measurement system was designed and installed in a local cottage cheese manufacturing plant. A cutting time prediction algorithm was developed using parameters generated from the backscatter profile. The cutting time prediction algorithm, Tcut = Tmax + β2 S, used two time-based parameters generated from the backscatter profile (Tmax and S) and one operator selected parameter, β2, to predict the coagulum cutting time, Tcut. The standard error of prediction for the algorithm was 6.4 min and was an improvement over the standard error of 8.7 min previously reported (Payne et al., 1998). The algorithm is more robust than that used by Payne et al. (1998) because it predicts cutting time based on a measure of coagulation kinetics, S, and eliminates the uncertainty of the culture starting time from the algorithm. In addition, a method was proposed for continuous monitoring of culture growth during the first 210 min of the process