Digester system

MT-Energie’s digester system, specifically for manure, is based on a one-step system. Manure is collected in the stables and then fed into a digester. The digester is heated to approximately 104 ºF with a retention time of 22-25 days to maximize gas yield at low investment costs. The effluent of the digester is then moved to the already existing manure storage at the dairy operation.

California dairies either use vacuuming, scraping or flushing as manure management system.

Our digester system works best for vacuumed or scraped manure. The TS content of vacuumed manure is about 10-12% compared to flushed manure at < 2%. This allows us to build smaller digesters to achieve required retention times, thus lowering investment costs. Manure fed into our digester systems should be mostly free from sand and other debris, as they set at the bottom of the digester over time, thus clogging up the system.

The advantages of our system are low investment costs, low operating costs and a high level of dependability.

Many California dairies use flushing as manure management system. This dilutes the manure substantially and therefore increases the volume to a level that makes it unprofitable to build a digester system consisting of round reinforced concrete tanks. A solution to this problem is covering of the already existing lagoons. Even though gas yields are not likely to be as high, biogas is still trapped and can then be conditioned to biomethane.   

Either way, whatever your manure managing system is, the most important factor is to produce enough biogas to feed the scrubbing system. This can be accomplished with either covered lagoons or complete-mix digesters.