Considering circular transitions: comparing central with decentralized water treatment
The purification of water is usually done at central water treatment plants. But what is the best circular solution? Is it centralized or decentralized water treatment? The last may, under the right conditions, deliver benefits in the field of sustainability, ecology and costs. However, it appears that these benefits can only be achieved when applied on a large scale. This is shown by the comparison of five scenarios with the TNO Water chain model for the Buiksloterham pilot area in Amsterdam North:
- Current situation with a central sewage plant in Amsterdam West
- Bio-refinery, decentralized water treatment on the district level
- Autarky, decentralized waste water treatment and a complete reuse of waste water on house/block level (a) for 1500 houses, (b) for 3000 houses, (c) for the entire district.
Decentralized water purification is cheaper, if applied on large scale
With current technology, decentralized water treatment is only a low cost alternative when applied on a large scale (entire neighbourhood or district, instead of a single home). The differences between alternatives arise in particular because of differences in costs for drinking water production.
Costs of several alternatives for decentralized water treatment
Energy usage, water intake, purge and water production for different technology scenarios.
Small energy benefits of decentralized water treatment
The use of energy is almost equal in all scenarios. The advantage of the decentralized treatment is mainly caused by the reduction of water intake and water discharge. This advantage appears particularly at the scale of the entire district.
Strategic investments in decentralized water treatment
Decentralised water treatment seems financially and in terms of energy, a feasible solution. Gradually implemented decentralized water treatment on the scale of a district or an entire city will also lower the investments in the water infrastructure, since it requires a significantly smaller network.
Download the full ACC report on “Circular Solutions Part 2 – Valuing the water chain” here (Dutch)