Date of Award
Thesis - Restricted
Master of Science (MS)
Civil and Environmental Engineering
Zitomer, Daniel H.
Zanoni, Alphonse E.
Crandall, Clifford J.
The treatment and disposal of high strength cheese wastewater is a concern for cheese manufacturers due its high organic, and fats, oils and grease content that make conventional wastewater treatment relatively expensive. Advances in anaerobic wastewater treatment and reactor design have increased the feasibility of full-scale anaerobic treatment of high strength industrial wastewaters and anaerobic treatment may be one solution for the treatment and disposal of high strength cheese wastewaters offering two main benefits: energy production and the potential for pollution reduction. The study described herein compared the performance of single-phase and two-phase pilot scale anaerobic sequencing batch reactors (ASBRs) for the treatment of raw high strength cheese wastewater. The ASBR is a batch fed, suspended growth process and consists of a single reactor used to achieve the desired level of treatment through four main stages - feed, react, settle and decant. It was hypothesized that the two-phase ASBR system would be able to sustain a higher maximum organic loading rate (OLR), produce more methane and provide greater COD, TSS, and FOG removals than the single-phase ASBR system. The results of the single-phase and two-phase systems are discussed in addition to the performance of the acidogenic and methanogenic reactors as separate systems. Results obtained in this study indicate that the raw cheese wastewater is highly amendable to anaerobic treatment. The overall average TCOD, SCOD, TSS and VSS removal efficiencies for the single-phase system were 93%, 98%, 91% and 93%, respectively, at an average OLR of 1.8 kg COD/m3-day and an average HRT of 22 days. The overall average methane production rate was 0.17 m3 CHJkg COD removed at 35°C and the average biogas methane content was 55%. However, the two-phase system achieved overall TCOD, SCOD, TSS and VSS removal efficiencies of greater than 90% at an average OLR of 2.0 kg C0D/m3 -day and an average HRT of 20 days. The overall average methane production rate was 0.20 m3 CHi/kg COD removed at 35°C and the average biogas methane content was 66%. Therefore, the two-phase system resulted in a higher effluent quality, higher biogas methane content and greater methane production than the single-phase system. As compared with the single-phase system, the removal efficiency for the two-phase system was more consistent throughout the study despite changes in the raw cheese wastewater characteristics. The acidogenic reactor removed greater than 50% of the FOG loading to the methanogenic reactor and increased the VFA loading to the methanogenic reactor by approximately 27%. The raw cheese wastewater may have already been partially acidified. In addition to acid productions, the acid reactor of the two-phase system performed as an equalization tank and a FOG trap. The low methane content of the biogas in the acidogenic reactor and the high methane content of the biogas in the methanogenic reactor indicate that good phase separation was achieved.
Wust, Elizabeth L., "Single-Phase and Two-Phase Cheese Wastewater Treatment by Anaerobic SBRs" (2003). Master's Theses (1922-2009) Access restricted to Marquette Campus. 4358.