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An advanced decentralized wastewater management planning study and demonstration project for the CSU Foothills Campus

Date

2010

Authors

Gallagher, Neal Thomas, author
Sharvelle, Sybil, advisor
Roesner, Larry A., committee member
Goemans, Christopher G., committee member

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Abstract

Expansion of development on the Colorado State University's (CSU) Foothills Campus has required examination of alternative methods to manage wastewater produced within the campus. This work builds off previous work which demonstrated that reuse of graywater and treated blackwater effluent could greatly reduce the cost of supplying wastewater treatment for the Foothills Campus (Criswell & Roesner 2005). The objective of this work was to provide insight into innovative decentralized wastewater technologies and management techniques to lay the groundwork for planning and design of optimal decentralized wastewater treatment architecture for the Colorado State University Foothills Campus. This objective was met through a planning study and a demonstration project examining anaerobic digestion of blackwater. A planning study was performed providing four potential scenarios for management of wastewater on the Foothills Campus. Source separation was recommended for proposed development, however combined plumbing in existing development was left unaltered. Four different wastewater streams were identified by type and level of treatment necessary: blackwater, graywater, laboratory process water, and laboratory sink water. Anaerobic digestion was recommended for primary treatment of blackwater because of the renewable energy (methane biogas) and nutrient rich effluent which are produced. Constructed wetland treatment was recommended for graywater and laboratory process water, to provide a source of reusable water for irrigation or toilet flushing. Technical feasibility of treatment of graywater from a campus setting in a constructed wetland has been previously examined, showing substantial levels of treatment. Technical feasibility of anaerobic digestion of blackwater from a campus setting is further examined in this study through a 108 L upflow anaerobic sludge blanket (UASB) treating raw blackwater from a building on the Foothills Campus. Reactor operational OLR varied between 0.21-0.39 kg COD/m3•d and HRT varied between 2.6-4.0 days during the study period. Total reactor operational time was 108 days at an effluent temperature of 28°C. Substantial removal of COD (72%), TSS & VSS (95%), and indicator organisms (1.4 log E. coli & 1.1 log fecal coliforms) was achieved over the study period. Effluent containing 79 mg/L dissolved ammonia nitrogen showed potential for use as fertilizer. Methane biogas produced during digestion (137 L CH4/kg CODinput) provided potential as a source of renewable energy. Overall performance of the UASB was sufficient for pretreatment of Foothills Campus blackwater. However, further examination of effluent, solids, and biogas reuse potential is necessary to determine supplementary treatment requirements and desired applications for extracted resources.

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Department Head: Luis A. Garcia.

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