Martin Construction Resource (MCR) offers anaerobic digester solutions, including consultation, engineering, procurement, and construction. Our digesters are built with proven technology and backed by over thirty years of experience and hundreds of successful biogas projects worldwide.
Martin Construction Resource has designed and built over one hundred agricultural digesters, the first being constructed in 1982. Today, MCR routinely provides round, mixed-tank-digester and covered-lagoon-digester designs for bio-gas production from farm and/or food waste.
Custom design often results in an MCR project costing less than the competition, while meeting or exceeding the performance of other systems in bio-gas and electricity output.
Our turnkey installation services include mechanical systems, bio-gas flares, digester pumps, electrical components, piping for generator hookup, hot water systems, gas piping, electrical wiring for utility buildings, and water separator systems.
MCR’s project services also include startup, digester operations, troubleshooting, training, and warranty support.
Farm Digesters and Digestion
A Promising Solution – Anaerobic Digestion Technology
Anaerobic digestion is one of the few manure treatment options that reduces the environmental impact of manure and produces savings and revenues. Anaerobic digestion will not solve all of the problems of manure. However, it will result in a return on the manure management investment and stop the manure from managing the owner.
Much information has been published about energy production from anaerobic digesters. Equally important, however, a properly designed and operated digester biologically stabilizes organic wastes, reduces odor, improves fertilizer value, and reduces pathogens. It can be expected that future regulations will address pathogen control. Anaerobic digestion is more extensively used in Taiwan and Europe where animal waste pollution has been regulated for a longer time. The US and Pacific Rim countries have seen a recent increase in the use of digesters due to tighter enforcement of regulations.
General Effect of Digestion on BOD, Nutrient, Pathogen and Weed Seed
Anaerobic digestion in a digester will reduce BOD and TSS by 80-90%. Odor is virtually eliminated. The digester will have minimal effect on the nutrient content of the digested manure. Pathogen reduction is greater than 99% in a 20 day HRT mesophilic digester (100 degree F). Half or more of the organic nitrogen (Org-N) is mineralized to ammonia (NH3-N). A small amount of the P and K will settle as sludge in most digesters. 30 – 40 % of P and K are retained in covered lagoon digesters. Digesters are very effective in killing weed seeds.
General Technical Description – Overview of Anaerobic Digestion
Manure consists of partially decomposed feed, waste feed, and water. Manure alone or mixed with process water and flush water is generally too concentrated to be decomposed aerobically in a manure treatment or storage structure, because oxygen cannot diffuse into solution fast enough to support aerobic bacteria. Therefore, manure is broken down sequentially by groups of anaerobic bacteria. An anaerobic digester is a vessel sized to grow and maintain a population of methane bacteria that feed on organic wastes placed in the unit. The bacteria grow without oxygen, decompose the waste, and produce methane as a useable fuel byproduct. Methane bacteria are slow growing, environmentally sensitive bacteria. These bacteria require a pH greater than 6.5 and adequate time to convert organic acids into biogas. Methane production is reduced as water temperature decreases.
Anaerobic digestion can be simply grouped into two steps. The first step is easy to recognize because the decomposition results in bad manure odors. The second stage methane bacteria consume the products of the first step and produce biogas – a mixture of methane and carbon dioxide. Biogas from a stable digester contains 60% – 80% methane. Biogas is virtually odorless but contains a small amount of mercaptans such as hydrogen sulfide.