We looked at commercial-scale vermicomposting for animal and human waste from several angles; efficiency, quality of finished product, pathogen reduction, and profitability. In brief, here was our findings; Efficiency - as a stand-alone system, vermicomposting was not as efficient as thermal composting, which was a more robust system that achieved a more stable product in a shorter amount of time. Pathogen Reduction - This is a subject of ongoing research, but, though worms were shown in several studies to significantly reduce pathogens, system efficiency remains a challenge. Worms do not reduce pathogens as effectively as the currently accepted methods for human waste management systems.
Rhonda Sherman at North Carolina State continues compiling data in these areas, and you would probably find her a wealth of information!
By the way, if you really want to get in to the icky but amazing on sewage remediation, let's talk black soldier fly larvae! Quality of Finished Product - Quality is a subjective term here, but speaking very generally, earthworm castings from a variety of feedstocks have been shown to produce plant growth impacts superior to thermal composts, to enhance, and even replace fertilizers in some scenarios, and to, in many tests, improve pest and disease resistance, but there is far too little data at this time to definitively characterize castings for gardening/agriculture. Ohio State University has the most comprehensive studies in this area; look for papers by Clive Edwards, Norman Arancon, and Scott Subler. Profitability - This is where commercial vermicomposting falls apart. As a point-source method of remediation, it's a great idea. The moment one puts either feedstock for the worms, or finished product on a truck for transport the economics fall to pieces. Vermicomposting in each home, and on each farm has a very real and measurable beneficial impact, but not in centralized facilities - and least not that we could find.
If you really want to delve in to this, check out Rhonda Sherman's web site at NCSU; she has the most comprehensive collection of data and articles with which I am familiar; http://www.bae.ncsu.edu/topic/vermic...ing/index.html
Read anything and everything by Dr. Clive Edwards of The Ohio State University (Rhonda has much of not most of his published work on her web site).