EPAD Process
1. Receiving
EPAD process can efficiently utilize versatile range of feedstock: biowaste, agricultural waste, wastewater sludge, pulp & paper sludge and other municipal and industrial biodegradable materials.
2. Pretreatment
The first step of the process is homogenization of screened feed. This pretreatment efficiently breaks solid materials’ cell structure maximizing the contact area for bacteria. This technology maximizes the input capacity and biogas production.
3. Feed Preparation
Next step of the process is feed preparation. The temperature and consistency of the feed are adjusted for the anaerobic digestion. Hydrolysation of material begins to take place.
4. Anaerobic Digestion
The prepared material is then fed into the reactor(s). Because of the high loading capacity, the reactor volume in EPAD is smaller than in conventional processes. This means significant savings in investment costs – reactor being the most expensive single unit in the process. The mixing technologys used in EPAD process is highly efficient, thus intensifying the functionality of the process. Studies show that the mixing of material in EPAD process is signifi- cantly better than in “conventional” processes. This leads to better digestation and higher biogas productivity.
The funnel shaped design of the bottom of the reactors ensures the safe output of the mineralized and highly nutritious digestate. The special design prevents the mixing of digestate with raw and foul smelling feed suspension – again increasing the overall efficiency of the EPAD technology.
5. Biogas Treatment
The biogas produced in the reactor is collected into the gas storage and further processed. Heat and electricity are produced in a CHP (combined heat and power) unit resulting in high energy efficiency. Furthermore the biogas can be upgraded to be used as fuel in vehicles , gas network and industrial processes (CNG) and converted into liquid (LNG –liquefied natural gas) for easier transportation and storage. The final gas utilization model is tailored for each process and end-user potential.
6. Digestate Treatment
The solid residue – digestate – is also further treated. Firstly, it is sanitized in order to kill potential pathogens. Hygienisation step after anaerobic digestion is a key feature of EPAD process. For this reason the end-products of EPAD are the safest available on the market.
After hygienisation the digestate is mechanically de-watered. Furthermore the digestate can be thermally dryed, pelletized and packed as ready-to use nitrogen and phosphourous rich fertilizers.
7. Circular System
EPAD process is self-sufficient as it produces the energy needed for the operations. The closed and efficient process gas treatment system ensures low greenhouse and carbon emissions without odour problems throughout the process. Reject water from the process is pretereated and partially recycled back into the process as water and nutrient addition.