@article {Rom:2001:1938-6478:527,
	author = "Rom, Paul R. and Rowan, James M. and Ziols, Gary E.",
	title = "Chicagos Start-up of Renewed Large Diameter Anaerobic Digesters with Worlds Largest Membrane Covers",
	journal = "Proceedings of the Water Environment Federation",
	volume = "2001",
	number = "14",
	year = "2001",
	abstract = "This case study documents the results of the start-up of the recently upgraded anaerobic digestion facilities for the Metropolitan Water Reclamation District of Greater Chicago&#39;s (MWRDGC) Egan Water Reclamation Plant. This 30 mgd plant has 4 - 110-foot diameter digesters with floating covers. The design included the following objectives:<P></P>&#60;list list-type="bullet"&#62; &#60;list-item&#62;<P></P>Replace the floating covers, improve the flexibility of operation, while increasing the effective liquid sludge storage.&#60;/list-item&#62; &#60;list-item&#62;<P></P>Provide increased sludge mixing and heating to provide for more efficient and enhanced stabilization of biosolids.&#60;/list-item&#62; &#60;list-item&#62;<P></P>Provide increased gas storage to improve gas utilization while safely handling digester gas.&#60;/list-item&#62; &#60;/list&#62;<P></P>To ensure a positive method of maintaining Class A or B biosolids, the detailed design included the following concepts with their related benefits:<P></P>&#60;list list-type="bullet"&#62; &#60;list-item&#62;<P></P>Two fixed cover primary digesters operating in parallel, with confined gas mixing and external sludge heat exchangers to improve mixing and heating - provides enhanced pathogen reduction and increased volatile solids destruction.&#60;/list-item&#62; &#60;list-item&#62;<P></P>Mesophilic digestion process in series configuration - ensures pathogen reduction and minimizes odor potential.&#60;/list-item&#62; &#60;list-item&#62;<P></P>Two gas/sludge storage tanks operating in parallel with intermittent pumped mixing and membrane covers (the World&#39;s largest diameter membrane cover installation to date) - improved gas utilization and increased sludge dewatering operation flexibility.&#60;/list-item&#62; &#60;/list&#62;<P></P>The Egan WRP processes sludge from both the Egan (30 mgd) and Kirie (40 mgd) WRP&#39;s and is a critical component of the District&#39;s biosolids management program. During construction, digester volume has been reduced by 50&#37;. Start-up and operational considerations include:<P></P>&#60;list list-type="bullet"&#62; &#60;list-item&#62;<P></P>Maintain existing operations, including digestion, to the maximum extent possible&#60;/list-item&#62; &#60;list-item&#62;<P></P>Construction of membrane cover digester - minimize digester down time&#60;/list-item&#62; &#60;list-item&#62;<P></P>Start-up of new process train with one fixed cover digester followed by one membrane cover gas/sludge storage tank&#60;/list-item&#62; &#60;list-item&#62;<P></P>Increased mixing in the primary digester - provides enhanced digestion&#60;/list-item&#62; &#60;/list&#62;<P></P>This project is currently under construction, with start-up of the first process train to begin in late summer of 2001. Steady-state conditions should be achieved in several months providing operational data to compare with the original construction. The figures and tables illustrate the process and document the results.",
	pages = "527-528",
	url = "http://www.ingentaconnect.com/content/wef/wefproc/2001/00002001/00000014/art00035"
}