The composting process uses a sludge and park waste mixture to optimize C:N ratio, as well as a semipermeable membrane, temperature control and forced aeration.
The pilot composting project was introduced in 2016 as a solution to recover nutrients from the sewerage sludge, as well as avoiding landfilling costs for sludge and garden waste. It is an example of bio-based circular economy where nutrients are recycled back to the soil. A membrane technology ensures optimum conditions for speeding the composting process, high temperature to destroy pathogens, production of good quality compost.
Park waste is shredded and mixed with sludge in a certain proportion (3 parts green waste: 1 part sludge) using a frontal loader. 200 cubic meter heaps are formed with aeration tubes at the base and temperature sensors are inserted and connected to a computer, so the process is partly automated. The heap is covered with the GORE® Cover semi-permeable membrane, to prevent moisture and heat loss, avoid release of unpleasant smells and leaching by rainwater. By using this technology, composting time is reduced from 6 months to 8 weeks.
In the first phase the technology was demonstrated and the resulting compost was applied on public land (green areas).
In the second phase, trial plots were set up to study the effect of the compost on different crops. It is estimated that in a couple of years the company will be able to bring a range of products on the market, namely different types of compost for flowers, vegetables etc.
The main stakeholders are the public service company and Mioveni municipality.
The total investment was around 150.000 € from the company’s own funds for the membrane and composting equipment. The project is operated by the company’s own employees.
Evidence of success
- Landfilling costs for sludge and park waste saved ~ 24.000 €/ year
- Large amounts of biowaste are no longer landfilled and are returned to green areas (circularity)
- Reduced storage time on the platform / less storage capacity needed using the membrane technology
- High quality compost, tested for pathogens and pollutants
- Expected revenues in the coming years from compost commercialisation
- Potential for training, sharing knowledge and creating new “green jobs”
In Romania there are currently no regulations for compost, limiting the possible applications of this technology. The “Law of Compost” was drafted and submitted to authorities, but no response/ progress so far.
Potential for learning or transfer
This good practice could be applied with good results by municipalities operating wastewater treatment plants with advanced biological treatment where park waste is also available. In 2017 Mioveni public service company established a training centre for staff involved in composting. In the first phase, the training services were destined for the company’s own staff, but it is meant to share the knowledge by offering composting know-how to other stakeholders who are interested in replicating the project. The company is working together with the Romanian Compost Association, seeking to provide also the legal framework for developing commercial products, thus turning biowaste into profit.
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