Blackwater treatment and reuse in practice in Södertälje, Sweden

Blackwater treatment and reuse in practice in Södertälje, Sweden

Sunita Hallgren Federation of Swedish Farmers (LRF) Policy advisor waste recycling Karl-Axel Reimer Södertälje Municipality Environmental manager Anna Calo (not present) Telge Nät AB Project manager

Either through organic waste from the food chain

or as new raw material from the crust of soil (P, S, K, Mg) or from air (N).

Each year a lot of plant nutrients are transported from swedish farms as cereals, potatoes, vegetables, meat and milk into the cities

These nutrients must somehow be replaced!

WWhy circulation of wastewater products? hy circulation wastewater products?

LRF’s view is that we in a sustainable society must circulate the plant nutrients back to agricultural land. Sustainability is crucial, and reuse of phosphorus, nitrogen and organic matter is an important step in right direction.

- put the quality of the ”waste” in focus!

How much pollution can the water withstand? (purification)

From:

How to maximize the management of nutrients? (conservation)

To:

LRF want a new approach in our society

Extremely low flush toilets, blackwater to closed tank + householdwater- purification through sandfilter

- we get concentrated blackwater in the closed tank

Small sewage - sorting systems in rural areas

Södertälje municipality 85 000 citizens

A collection and treatment system for recycling of nutrients from organic waste and wastewater in a sensitive rural area

[email protected]+46 (0) 8-550 221 26

Treatment plant for 500 households based on two methods for sanitisation

• Sanitisation by urea treatment When urea is converted to ammonia

the pH in the sludge increases, which leads to reduction of pathogens in the sludge.

Addition of urea increases the

nitrogen quantity in the manure. Two-four weeks depending on the

amount of urea added and the pre-heating temperature.

Well sealed treatment tanks with

compost filter for pressure equalization. The filters reduce odours and catches possible ammonia.

• Wet composting Collection of black water from

septic tanks and organic waste connected to extremely efficient water saving systems.

Collection of organic waste and

manure.

- Aerobic thermophilic process (wet composting process), where the materials reach at least 52 °C during a minimum of 10 hours. 2 weeks

- Preheat to about 40 °C for , 1

week Aeration is supplied by an

immersed ejective aerator.

Wet composting and Urea treatment for a safe reuse of toilet waste in agriculture

Supervision in Södertälje on small wastewater treatment plants

• The environmental act • Strive to close the loop • Highly eutrophicated area • Supervision is related to local agriculture • Local policy for ecosanitation

Man made wetlands (protecting lakes and rivers) Protection of the river

Farming (closing the loop for plant

nutrients)

Sustainable wastewater treatment is: Keeping and safely use the nutrients on land!

Local municipal policy/guidlines for Ecosanitation in Södertälje • Treating the black water separately • Minimal use of water • Safe system for hygienization • Suitable system for agriculture

Experiences

• Economical challenges • Acceptance of new technique • It´s a solid system. No complicated process for the household to control/supervise

Urban and rural areas must be linked together…food in – nutrients back!