Volatile fatty acids production from fermentation of secondary sewage sludge : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering

Sludge fermentation is used worldwide as an economical means to produce volatile fatty acids (VFA), which can be used as readily available carbon in biological nutrient removal (BNR) systems. In this research, secondary sludge was tested for its potential to generate VFA. Fermentation of secondary sludge was carried out in a lab-scale sequencing batch reactor (SBR). The SBR was fed with secondary sludge of 1% total solids and run with hydraulic retention time (HRT) of 48 hours and 28 hours in phase 1 (40 days) and phase 2 (12 days) respectively. The SBR produced net VFA (expressed as acetic acid) of 365 ±62.5 mg VFA HAC /I which was equivalent to a VFA yield of 0.28 ±0.05 mg VFA HAC /mg VSS feed during phase 1. A change in operating HRT from 48 hours to 28 hours led to a reduction in solids retention time (SRT) from 2.65 days to 2 days in phase 2. The reduction in SRT during phase 2 led to poor hydrolysis and hence could not support the fermentation. Net VFA generation decreased during phase 2 and reached 0 mg/I. Acetic acid was the main acid produced comprising 45% of total VFA content during the run with 48 hours HRT. The effect of total solids (TS) concentration on secondary sludge fermentation was tested using batch experiments. The batch with 2.8% TS secondary sludge showed a maximum net VFA production of 60 mg VFA HAC /I, which appeared to be superior to the 1% TS secondary sludge batch fermentation where no net VFA production observed throughout the test period. Primary sludge (3% TS) exhibited 1200 mg VFA HAC /I in a batch fermentation, which was superior to the net VFA produced during secondary sludge (2.8% TS) batch fermentation. The effects of sonication on fermentability of primary and secondary sludges were tested. A sonic power application of 0.0017 Watt/ml/min density increased soluble content of primary and secondary sludges. In batch fermentations, sonicated secondary sludge improved fermentation over unsonicated secondary sludge. A maximum net VFA production of 130 mg VFA HAC /I was observed in the secondary sludge batch fermentation. In this research work, an investigation into inhibiting VFA degradation in secondary sludge batch fermentations was also carried out. The effects of a methanogenic bacteria inhibitor (bromoethane sulfonic acid) and low pH (range of 4.02-6.07) were considered. The addition of 1 mM bromoethane sulfonic acid (BES) in secondary sludge (1% TS) batch fermentation successfully inhibited VFA degradation. pH values as low as 4.02 showed an inhibitory effect on secondary sludge (1% TS) batch fermentation which led to poor hydrolysis and hence no net VFA generated during the test period. However, low pH values reduced the VFA degradation rate in the batch fermentations. Secondary sludge used in the present research showed the potential to generate VFA. The amount of VFA produced in the present work showed the potential to improve the performance of a BNR system. Moreover, in batch fermentations, VFA generation was improved using various pre-treatments like sonication and BES addition

Development and fabrication of a solar cell junction processing system

Development of a pulsed electron beam subsystem, wafer transport system, and ion implanter are discussed. A junction processing system integration and cost analysis are reviewed. Maintenance of the electron beam processor and the experimental test unit of the non-mass analyzed ion implanter is reviewed

Structure and Finances of U.S. Farms: 2005 Family Farm Report

Most farms in the United States- 98 percent in 2003- are family farms. They are organized as proprietorships, partnerships, or family corporations. Even the largest farms tend to be family farms, although they are more likely to have more than one operator. Very large family farms and nonfamily farms account for a small share of farms but a large-and growing-share of farm sales. Small family farms account for most of the farms in the United States but produce a modest share of farm output. Median income for farm households is 10 percent greater than the median for all U.S. households, and small-farm households receive substantial off-farm income. Many farm households have a large net worth, reflecting the land-intensive nature of farming.Agricultural Finance, Consumer/Household Economics, Industrial Organization,

Structure and Finances of U.S. Farms: 2005 Family Farm Report

Most farms in the United States—98 percent in 2003—are family farms. They are organized as proprietorships, partnerships, or family corporations. Even the largest farms tend to be family farms, although they are more likely to have more than one operator. Very large family farms and nonfamily farms account for a small share of farms but a large—and growing—share of farm sales. Small family farms account for most of the farms in the United States but produce a modest share of farm output. Median income for farm households is 10 percent greater than the median for all U.S. households, and small-farm households receive substantial off-farm income. Many farm households have a large net worth, reflecting the land-intensive nature of farming.Agricultural Resource Management Survey (ARMS), family farms, farm businesses, farm financial performance, farm-operator household income, farm operators, farm structure, farm type, multiple-operator farms, multiple-generation farms, small farms, contracting, Farm Management,

Health Coverage and Access to Care for Hispanics in "New Growth Communities" and "Major Hispanic Centers"

Examines healthcare coverage for Hispanics when they migrate from cities to smaller urban and rural areas, and encounter roadblocks such as language barriers, lack of insurance, and access to health clinics

A Tribute to Richard B. Drake & Ronald C. Wilson: Reflections on How Two Historically Appalachian Colleges Responded to Tumultuous Times

Dick Drake and Ron Wilson taught history at Berea and Warren Wilson Colleges for much of the second half of the 20th century. In an earlier era, Berea and Warren Wilson’s predecessor, Asheville Farm School, were prominent Appalachian mission schools and key contributors to the Council of the Southern Mountains. The careers of Drake and Wilson reveal much about their respective institutions’ responses to traumatic changes in the nation, the Appalachian region, and American higher education in a turbulent, still inadequately understood, era. The two history professors’ responses to dramatic new directions in humanities scholarship – particularly the emerging field of Appalachian Studies – and the two college’s evolving approaches to regional outreach will be my primary concerns. Drake and Wilson passed away in June 1988 and were mentors for me at two critical junctures in my academic career. My primary sources will be: Shannon Wilson’s Berea College: An Illustrated History and Warren Wilson College: A Centennial Portrait that Reuben Holden and I composed in 1994. For broader contexts, I will draw from Ron Eller’s Uneven Ground: Appalachia Since 1945 and H.W. Brands’ American Dreams: The United States Since 1945. Was part of the Panel discussion: Higher Education