In the future, the anaerobic fermentation and utilisation of sludge from wastewater plants will play an
increasingly important role. To ensure an economically and ecologically sustainable solution, more and
more municipalities decide to optimise the energy potential of their sewage plants. For a plant dimension
of 20,000 to 30,000 PE (population equivalent), biogas plant manufacturer WELTEC BIOPOWER from
Lower Saxony, Germany, offers an attractive retrofit package for anaerobic sludge treatment.
Sustainable sludge treatment strategies are vital – also in view of the fact that many countries plan to
discontinue the use of sludge as fertiliser. In some countries, this plan has already been enforced. Moreover
the energy potential of this resource and the part that remains unused in sewage plant operation are still
high. These framework conditions as well as rising energy prices amplify the need for municipalities to act.
For this reason, WELTEC BIOPOWER has developed an optimised anaerobic sludge treatment approach:
Following the preliminary treatment of the wastewater and the removal of pollutants, anaerobic sludge
fermentation – during which the sewage gas develops – is the process step that offers a particularly high
energy utilisation and saving potential for the sewage plant.
„With this possibility to generate power for their own consumption, sewage plants can cut their energy
costs by up to a quarter“, says Hajo Schierhold, Sales Manager of WELTEC BIOPOWER. „Additionally, the
heat produced by the cogeneration unit can be used directly and inexpensively to heat buildings and the
digester in order to accelerate the entire fermentation process“, adds Schierhold.
The fermentation also reduces the amount of sludge, which ultimately results in lower sludge disposal
costs. „This reduces the sewage plant operating costs even more“, explains Hajo Schierhold. Apart from the
microeconomic benefit, a macroeconomic benefit also arises for the eco-balance: The reduction helps avoid
harmful greenhouse gas emissions that diffuse into the atmosphere during aerobic sludge stabilisation.
However, to benefit from these advantages, appropriate plant technology must be implemented: A suitable
anaerobic unit is required for sludge stabilisation under consideration of the properties of the sludge. This
unit must be equipped with a special roof for intermediate storage of the fermentation gas as an energy
source for the cogeneration (CHP) supply.
The modular digesters of WELTEC BIOPOWER are especially suitable for this purpose: In these mature
stainless-steel bio-reactors, harmful carbon compounds are efficiently converted to methane by means
of microbiological decomposition processes in the absence of air. „In view of the mounting energy prices
and the advantages of a reduced sludge volume, the upgrade of sewage plants with a view to utilisation
of fermentation gas for energy purposes is especially attractive for the range of 10,000 to 30,000 PE“, says
Hajo Schierhold. Particularly for a population equivalent of 20,000, the plants have the highest share of own
energy consumption and thus the highest saving potential.
Obviously, this news has already spread to Hungary, France and Finland: In these countries, operators
have already invested in the WELTEC package comprising specially designed fermenters, high-quality
components and optimised energy extraction processes. Moreover, investors appear to be especially
impressed by the extensive biogas technology expertise, from the ground slab to digester technology
to CHP systems.
For more information about the anaerobic sludge treatment, visit WELTEC BIOPOWER from May, 5th to
9th at the IFAT in Munich (Hall / Booth: A3/523).
For a plant dimension of 20,000 to 30,000 PE (population equivalent), WELTEC
offers an attractive retrofit package for anaerobic sludge treatment.
In 2014, WELTEC BIOPOWER GmbH, one of the first manufacturers of biogas plants, celebrated
its 13th anniversary. WELTEC is one of the pioneers of the constructors of biogas plants. Based
on the modern approach of experienced engineers, the company from Vechta, Germany with its
expertise of a staff of close to 80, offers complete biogas plants from one source and has developed
to a leading constructor of biogas plants in the world.
As the hydrogen sulphide and ammonia compounds contained in biogas corrode unprotected
parts, WELTEC builds the digesters from stainless steel. This ensures a long useful life of the plant.
The manufacturing depth also guarantees a consistently high standard regardless of the location
and ensures an export rate that is far above the industry average.
The plants have a modular structure. WELTEC uses only proven system components and develops
most of the technologies along the entire value chain internally: digester technology, mixing
technology, control technology, hygienisation systems, and digestate processing solutions
originate from the company.
By means of its comprehensive services, WELTEC ensures the technical and economic stability of
the biogas plants. The CHP service guarantees stable output, the biological supervision ensures
continuous monitoring of the relevant parameters, and systematic repowering makes sure that
the biogas plant is always up to date. Operators can choose from a range of service packages of
different types and scope.
One of the main strengths of WELTEC is the ability to deliver individual and flexible solutions
worldwide – from compact plants to large computer-controlled plants in the megawatt range,
waste recycling plants, and biogas parks with gas processing technology.