sustenso processes agrarian waste streams
For input into the digester, Sustenso uses amongst other waste all green waste form the agricultural sector (vegetables, fruit, horticulture), corn, grass and cocoa shells
the digester
Using a digester to extract gas from agrarian waste offers sustainable and profitable opportunities. The key to success is a professional approach and a comprehensive understanding of all steps in the process. The digester produces biogas and so-called digestate. The digestate consists of a liquid phase and a solid phase. Sustenso upgrades both the biogas and the digestate into useful and marketable components.
Minimal waste
Due to the circular approach of Sustenso, the amount of unusable material, and hence the road transport, is minimal.
from biogas to green gas
One of the end products that Sustenso delivers is green gas. The biogas formed in the bio-digester consists of 55%-60% methane gas and 40%-45% CO2. In order to supply usable green gas, the level of CO2 has to be drastically reduced. . Sustenso achieves this using proven purification technologies (washing, cryogenic separation, membrane filtration, adsorption). Sustenso delivers the purified gas to the gas grid.
Digestate
The digestate is separated into its useful components in highly-concentrated, small volumina.
from CO2 to valuable microorganisms
Besides green gas, the purification of biogas also yields CO2 as a by-product. This CO2 is valuable for horticulture. Moreover, Sustenso uses some of this CO2 as a raw material for the production of valuable microbial biomass. To accomplish this, Sustenso exploits the ability of certain microorganisms (bacteria or algae) to use light to capture CO2 in the shape of new biomass: this is known as photosynthesis. This process takes place in an installation that is as clean as it is innovative: the photobioreactor. Depending on the circumstances, either sunlight or LED light is used. This process removes CO2 from the air and significantly reduces the CO2 footprint of the entire waste processing operation. Moreover, the new microbial biomass has multiple applications, ranging from fermentable material (returning it to the digester) to marketable supplements for animal feed or human food products. The market value of the biomass produced in this way, depends on the type of bacteria or algae that are used.
Lgem Technology for growing micro-organisms
Under controlled conditions, micro-organisms are fed with CO2 and (sun) light. The micro-organisms multiply and can be harvested.
Green Gas
Upon external control of its quality, the green gas that has been separated from the biogas, is delivered to the gas net.
from digestate to usable products
The digestate produced by the digester consists of a liquid component containing various nitrogen compounds and mineral nutrients (including potassium). The rest is solid material consisting primarily of phosphate (bound to organic material). The liquid and solid parts are separated by means of simple mechanical filtration. Fine particulate matter is removed from the separated liquid by means of coagulation. The liquid is then sent to a membrane-bioreactor in which bacteria convert the undesirable ammonium into usable nitrate (nitrification). In the next stage of the process potassium and nitrate are concentrated as potassium nitrate by means of reverse osmosis. Potassium nitrate is a major component of fertilizer and the clean waste water can be safely discharged.
The solid material which Sustenso’s digestate processor delivers as its end product, contains the valuable component of concentrated phosphate. Depending on demand from the market, Sustenso can further concentrate the solid material (thickening) or remove the organic elements by means of combustion. What remains is a high concentration of phosphate salts.
Spirulina
The CO2 released during the fermentation process can be fixed into a variety of microbial species that can subsequently be used as additional input for the digester, as supplement to fodder or as supplement to human food, e.g. Spirulina.