CO₂-compensation through the construction of constructed wetlands with biomass production

Plant purification plants with connected biomass production are characterized by positive CO₂-effects on many levels:
 

1. The plants absorb CO₂ from the air, especially if the plant is coupled with the production of renewable raw materials. The wastewater treatment plant thus acts as a carbon sink. This mechanism is designed in such a way that it can also be calculated and certified using a CDM method.
2. In comparison with other approaches, this technology generally does not consume any energy => no CO₂ production! If, in exceptional cases, there is a low electricity requirement, this can be covered CO₂ -neutrally by a photovoltaic system with a simple electricity storage tank.
3. Plant-based purification systems decompose aerobically, not anaerobically, which largely avoids the formation of methane.
4. The harvested biomass (e.g. bamboo) is deposited in landfills (open pit mines, etc.) or alternatively used as building material, thus removing it from the carbon cycle and serving as a carbon sink in the long term.
5. This approach is also an emission avoidance strategy, as CO₂-emitting processes (= conventional sewage treatment plant) are replaced by CO₂-absorbing processes.

 
The approach will increase the total amount of avoidable greenhouse gases compared to conventional wastewater treatment.

The investments are made in developing countries where the positive effects are particularly large. We currently we have corresponding contacts in Vietnam, Kenya, Jordan and Zambia. The first project locations in these countries have already been identified and the first plants are already under construction.
Project start is the first of September 2019.

The production of one ton of bamboo biomass removes about 1.8 tons of CO₂ from the atmosphere.

This requires about 1 m³ of purified wastewater (water is not the limiting factor for biomass production, the excess purified water is discharged). The decisive factor is the available area. The average growth time of a single bamboo trunk until harvest maturity is 6 months, depending on the location. The yield is to be calculated with 21.6 tons dry matter or 10.8 tons carbon per year and hectare, corresponding to about 3.6 kilograms carbon dioxide / square meter from the atmosphere per year.

A bamboo plantation with an area of one hectare would thus remove about 36 tons of CO₂ per year.

Ideally, the wastewater treatment technology envisaged in the C3 project does not require any energy. On the other hand, for conventional treatment (e.g. activated sludge process) with an annual specific energy requirement of approx. 750 kWh/m³ wastewater treatment capacity must be assumed.

With a plant size of 100 m³/day, this results in a (theoretical) energy saving of 75,000 kWh per year, corresponding to approx. 40 tons of CO₂.