Sludge-to-energy: STP Tiel
Tiel, The Netherlands
Thermophilic digester volume:
14.5 tonnes of dry matter/day
1.5 million Nm3/year
2000 ppm to <40 ppm
1.2 t/day (40% dry matter)
440 kg N/day
By order of the Rivierenland Water Board, STP Tiel had to be converted into a 100% energy-neutral plant. Colsen is the technology supplier in the consortium that was awarded the contract for the “Sludge digestion optimisation – Tiel STP” tender. By applying the following technologies, the consortium managed to win the tender on the basis of total cost of ownership.
Thermophilic digestion with DIGESTMIX®
The 4,000 m3 thermophilic digester is kept at a stable temperature of 52 °C, to ensure that sludge is broken down as efficiently is possible. 3 DIGESTMIX® systems keep the entire digester at the right temperature and make sure the sludge is mixed properly.
Biological biogas desulphurisation with BIDOX®
The biogas produced by the WWTP is desulphurised in a BIDOX® system, so that it can be used in the CHP system to produce heat and electricity.
Phosphate recovery in the ANPHOS®
The ANPHOS® reduces the phosphate load from the sludge line to the waterline. In a two-step process, phosphate present in the reject water is deposited as struvite, which can be removed and used as a sustainable fertiliser.
Nitrogen removal via Anammox in the NAS-ONE®
The old mesophilic digester at Tiel STP has been converted into a NAS-ONE® system, which uses anammox bacteria to remove nitrogen with a removal efficiency of >80% TN and >90% NH4-N. The treated effluent that emerges from the NAS-ONE® ends up in the waterline of Tiel STP.