Envor Protech Oy

Anaerobic Digestion Plant



Anaerobic digestion is the most environmentally sustainable, energy efficient and economical solution when compared to other waste treatment methods such as composting, landfills or combustion. In anaerobic digestion variety of natural micro-organisms function in the absence of oxygen to degrade the organic material into biogas (mixture of methane and carbon dioxide) and water. The organic residual (digestate) can be used as raw material for green fertilizers. The different phases of this metabolic process, where variety of biochemical reactions occur, are hydrolysis, acidification, acetogenesis and methanogenesis. Our expertise lies in the deep understanding of the chemistry between these biochemical processes as well as in the long experience in operating the actual industrial level EPAD-plants.

EPAD technology is based on continuous, industrial scale, anaerobic digestion process. EPAD process has been developed by the owners of Envor Protech Oy in course of  20 years. The process is the first, stable, large scale continuous process in Finland that is still working - the first reference being the biogas plant in city of Forssa 1999.

Due to efficient process and equipment design the capacity of EPAD is higher than that of other available processes. Based on customer’s needs and feedstock the process can be tailored to be either mesophilic (low temperature) or thermophilic (high temperature)

Each plant we deliver is tailored to match the needs of our customers. The process is designed to insure maximum bioenergy recovery and resources recycling. We aim to design closed loop systems where material and energy flows are optimized to produce environmentally sustainable, highly efficient process. Energy produced in the process can be utilized as heat, electricity or fuel.

The scope of our services includes for example feasibility studies, process design packages, key equipment deliveries, turn-key solutions as well as Build, Own and Operate – solutions.


EPAD process can efficiently utilize versatile range of feedstock: biowaste, agricultural waste, wastewater sludge, pulp & paper sludge and other municipal and industrial biodegradable materials.


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.

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.

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.

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.

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.

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.

Low life cycle cost

  • low investment cost due to EPAD technology
  • low operation & maintenance cost due to optimized process and equipment choices
  • high biogas production rate
  • energy efficient process solutions with high net energy production

Steady, safe and reliable operation

  • proven process references with a high utilization rate
  • automated and controlled process operations
  • reliable process and equipment solutions
  • high quality components with long life time
  • 24 h technical support

Pure, mature & nutrient rich end products

  • no emissions or odour problems
  • sterile and hygienic end products
  • high nutrient recovery (nitrogen and phosphorous)

Flexible solutions

  • tailored to customer's needs – flexible and adjustable process operations
  • adaptability to different climates
  • retrofit into conventional plants

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