Biogas Plants Biodigesters

The bio-digesters are «biological engines» allowing the transformation of organic matter (liquid or dry) into biogas and stabilised organic fertiliser.


Biogas plants are facilities with three purposes:

  1. Treat the organic matter (liquid or solid) by biological process.
  2. Generate a renewable natural gas for energy usage.
  3. Stabilize the organic material for better use as fertilizer.

Bio-digesters convert organic matter carbon in methane (CH4) and carbon dioxide (CO2). The nutrients in organic matter (N, P, K) are not removed and are the by-products (sludge, treated effluent). These by-products become excellent organic fertiliser.


Implementation average per year:

  • 100.000 m3 of biodigesters
  • 15´000.000 m3 of methane (CH4)
  • 10 MW


Main models developed by BIOTEC:

  • UASB = Upflow Anaerobic Sludge Blanket (see more)
  • RAC ® = Contact Anaerobic Reactor (see more)
  • RAFAC ® = Contact Upward Flow Anaerobic Reactor (see more)
  • Bioseco (see more)

Composting plants

Composting is a technique of processing organic by-products (solid).

The objectives of the composting process are:
  • Reduce the volume and the weight of material to be transported
  • Stabilize organic matter to turn it into compost
  • Replace chemical fertiliser in the field
  • Control odours
  • Recycle the nutrients to the soil
  • Evaporate wastewater and sludge

Depending on raw material, land available, environment, weather conditions, objectives and industry policy, BIOTEC engineers composting plants by front turner (traditional system), by side turner and/or by forced aeration.


  1. FT: Traditional system with front turning
  3. LT: Alternate system with side turning which allows greater height of piles and avoid spaces between piles
  5. FV: Forced aeration. In this system it is not necessary to proceed to turning as long as the material is sufficiently loose

Liquid Organic fertilisation systems

For the effluents and wastes not to be discharged in rivers or landfills, it is necessary to find ways to return the organic matter and nutrients they contain to the soil. Agronomy and agricultural engineering are a complement to environmental and sanitary engineering. Fertilisation with fresh or decomposed organic material is already common practice in agriculture around the world. Liquid Organic Fertilisation is less well known but equally important.

When liquid application technologies do not exist or are not satisfactory for technical or financial reasons, BIOTEC engineers innovative solutions for organic fertiliser application. The principles and features largely depends on the type of crop. This is the case of "FORLIM"® (Liquid Organic Fertilisation Monitored System), that allows the application of treated effluent and sludge from the bio-digesters in a controlled fashion on the plantations. The FORLIM uses a computer system (SCADA) and a GIS (Geographical Information System) allowing online control and tracking of the fertilisation process.

The FORLIM generate periodic reports on fertilisation for the management and/or environmental authorities.

Dosage of nutrients per hectare per year are similar to the dosage used for chemical fertilisation.

  • Zero discharge to rivers and water bodies
  • Providing and adding value to anaerobic sludge and effluents
  • Replacement of chemical fertiliser in the estates
  • Improvement of the soil
  • Increase in performance
Order of magnitude:
Crop Dosage (liquid organic fertilizer).
OIL PALM: 100 - 300 m3/ha-year
SUGARCANE: 50 - 300 m3/ha-year
CITRUS: 1000 - 2000 m3/ha-year


BIOTEC designs, builds, implement and supervises its solutions on an industrial scale, with its own technology and through thorough quality control both internal as well as with its suppliers.


The implementation of these projects can be done in two ways:
  1. Full turnkey: BIOTEC is responsible for the entire project, from the design and construction of the plant to commissioning.
  2. Partial turnkey: the client is responsible for the civil works and the direct purchase of certain equipment.


A good installation must be correctly operated to take advantage of its full potential. BIOTEC is committed to its customers and will operate the plant for the first two years. In this way the plant will operate at the designed performance (KPI) and the customer’s operational team can be fully trained.

BIOTEC operates plants under two models:
  1. Management: BIOTEC participates in the operation with its own staff, leading and training the client’s team.
  2. Supervision: On-line monitoring (SCADA system) with periodical audits.


BIOTEC designs and builds thinking
as operator