Facility components

After the facility got new owners, additional lines and equipments have been added and will be added in the future in order to enable R&D at the frontline. Here the Anammox treatment can be named as an example. Other equipment that can be used in facility includes for instance equipment for treatment with ozone, UV light, hydrogen peroxide and activated carbon.

The plant can be used for various projects to develop and optimize existing and new systems or components. It also serve for tests and demonstrations for new methods and equipment.

Line 1: Aerobic treatment with activated sludge
and biological nitrogen — and phosphorous removal
Line 1 is designed as a conventional Swedish plant with the following steps: pre-precipitation, sedimentation (1), six stages of biological treatment (2), secondary sedimentation (3), and also sand filtration (4) that offers the possibility of post-precipi-tation. Utilizing return flows and aeration or tank mixing, the UCT process (first developed by University of Cape Town) has been tested for removal of both nitrogen and phosphorous. During digestion of sludge from the biological phosphorous removal process, most of the phosphorous is released in a concentrated flow. Tests have shown that it is possible to extract the pure phosphorous substance struvite from digestion supernatent.
The other tested method for producing high quality water and a concentrate that is rich in nutrients is entirely aerobic with no return flows except sludge. It is then combined to a reverse osmosis (RO) step. Line 1 is basically a copy of the nearby Henriksdal treatment plant complemented with biological phosphorous reduction. Sludge produced during the wastewater treatment process is thickened, digested and dewatered (5). The line serves as a reference for the other two lines.

Line 2: Aerobic treatment with membrane bioreactor and reverse osmosis
Line 2 consists of various barriers for wastewater treatment: a drum filter (1 ; instead of pre-sedimentation), an aerobic reactor with an immersed microfilter (2) (membrane bioreactor, MBR) and a reverse osmosis (RO) facility (3). The process steps are very compact and treat wastewater very successfully. The RO facility more or less produces drinking water at the same time as nutrients can be recovered. Nitrogen and biological phosphorus removal are achieved by dividing the reactor into various zones and by recirculating flows. However, an RO stage is also required to achieve very low levels of nutrients. The combination of a heavily loaded MBR and RO makes it possible to recover most phosphorous and nitrogen (as well as potassium and sulphate). Sludge created by wastewater treatment is thickened, digested and dewatered (4).

Line 3: Anaerobic treatment with fluidized bed
Line 3 is an anaerobic fluidized bed. The biggest problems with the fluidized bed are that the sand drift destroyed some components. 

Line 4: Anaerobic treatment with UASB and biological nitrogen reduction
Line 4 is an Upflow Anaerobic Sludge Blanket (3) (UASB) type reactor. Under appropriate hydraulic conditions, the bacteria form their own substrate to grow on. Wastewater can be pre-treated by the addition of chemicals (1) and either sedimentation or flotation (2). The UASB facility consists of two mixing chambers (3a) and two reactors (3b) with gas separation (3c) that can be run in series or in parallel. The tertiary treatment is performed through chemical precipitation to recover phosphorous (4), and through biological polishing (5) for nitrification. Nitrogen reduction takes place in tanks with suspended biomass carriers (biofilm process) in order to obtain a solution as compact and effective as possible. Nitrogen reduction with reverse osmosis (6) (RO) is the reference process. Sludge treatment is performed through thickening (7), digestion (8) and dewatering (9). In order to remove enough organic matter and nutrients, the wastewater is sent through a last stage of nitrification and denitrification in tanks with suspended carriers followed by a drum filter for clarification. As in the other lines if nutrients are to be recovered, an RO stage is required.

Line 5
Line 5 consists of various components for sludge handling. It consists of sludge thickener, two digestion chambers, sludge tanks and decanter centrifuges from Alfa Laval. The digester with gas measurements makes it possible to either perform digestion test with sludge from the different lines,  recirculation of the reject water, or to perform separate digestion experiments.

Line 6
Line 6 is an anaerobic MBR with capacity 50-100 l/h. The membrane package is situated outside the membrane reactor, and a pump creates the necessary pressure for the membrane. As with all anaerobic treatment methods a final aerobic treatment step is required to provide an acceptable effluent.