How to acquire a waste water treatment plant

When upgrading your onsite sewage water treatment, there are several things to consider.

It is not always easy to understand what rules apply in your municipality and how the installation works. We will guide you through three important steps in the process - thereafter, your biological sewage water treatment is ready for use and you can expect a high-quality long-lasting wastewater treatment on your property.

Step 1: Treatment demands

The treatment demands are decided by the municipality and depend on the distance to sensitive water streams and what type of soil you have on your property. If you do not already know what demands apply to your property, we will provide you with that information.

Step 2: Get permission

Before installing a new wastewater treatment plant you need permission from the authorities. We gladly assist you in filling out the application form.

Step 3: Installation

We are happy to visit you in order to advice you regarding the best solution for your property (free of charge). ACT NaturalTM is easy to install and we can help you to find a contractor who can perform the installation.

We are available for questions throughout the entire process - from the environmental permit application to the fully installed facility!


The first and most important thing is to plan the installation well before the work begins. Follow these guidelines to get a good start.

Ground and excavation work
• Plan to achieve a natural slope from the outlet in the house to the inlet of ProACT™ (approx. 0,5-1 cm/m).
• InterACT ™ must be located at a higher level than ProACTTM to ensure that the wastewater pumped to InterACT™ will not stay in the tube when the pumping sequence ends. The water will instead flow back into ProACT™ to avoid the risk of freezing. The level difference should be from 0.3 to 2.0 meters.
• The outlet from InterACT ™ to the inlet of ReACTTM is installed with a natural slope and thereafter for example out in a stream or drainage pipe.
• ProACT™ needs to be placed so that only the lid is visible above ground level.
• InterACT™ should be located at such depth that the top ends up approximately 20 cm above ground level.
• Both ProACT™ and InterACT™ consist of cylindrical tanks measuring 2 meter in diameter and 2,8 vs 2 m in depth, and they will be filled with water once everything is installed. It is therefore important to prepare the ground under the tanks in such a way that it can bear the total weight of the tanks without risking subsidence.

ProACT™ – an anaerobic process

The ProACT™ tank is divided into two chambers and a distribution well in the centre.

The wastewater enters the first chamber where a pre-dissolving process takes place (an anaerobic process that can be compared to a digestion process). The sludge-containing water will thereafter be passed on to the second chamber where it is exposed to a bio bed. The micro-organisms in the bio bed degrade the remaining sludge to a level where it can easily be passed on to the next step in the process. After passing the bio bed, the wastewater is led into a distribution well mounted in the center of the tank. Here, microorganisms degrade the organic compounds even further before the water pump passes the water on to the next treatment step, InterACT™. In case of power failure there is a spare capacity of at least 700 litres in ProACT™.

HVAC works

The tubing from the house to the system and between InterACT™ and ReACT™ should be performed with standard 110 mm sewage pipes.
If existing sewage pipes from the house to ACT Natural™ are to be used, the quality of these should be controlled. Not only because wastewater may leak out from such pipes, but also because rain water and ground water can leak in through old/bad pipes and thereby cause volume overload of the treatment system (ACT cannot take any responsibility for consequences of such overloads in the system).

Electrical wiring
A micro-computer controls and monitors the ACT Natural™ system. From this box cables are connected to the air pump, the water pump, the heating cable and the water level meter.

A small alarm lamp should be mounted at an appropriate location where it can be seen daily.

Connection between ProACT™ and InterACT™

The connection between ProACT™ and InterACT™ is located so that the water falls from InterACT™ to ProACT™ in the end of the pump cycle so that water does not stay inside the tube between pump cycles, but flows back to the ProACT™. This is to avoid freezing in the tubes.
It is essential that ProACT™ is placed at such depth that the outlet is located 30-200 cm lower than the inlet of InterACT™, a smaller level difference could cause water to stay in the pipe after the pumping cycle, whereas greater level difference requires a more powerful pump (which can be provided from Alnarp Cleanwater if necessary).

InterACT™ – Aerobic process

The pre-processed wastewater is pumped from ProACT™ to InterACT™ gradually to spread out the load on InterACT™ over the day. This is automatically controlled by the microcomputer. The inlet leads the water down, close to the bottom of InterACT™ where the water circulates at a speed of up to 2 m/s. The circulation is ensured through an air pump that creates a swirled water flow (Vortex flow) while the water is aerated. In this free circulating area, a separation of organic matter takes place. Since the organic matter is lighter than water, it rises and is exposed to the bio bed above this free circulation area. The micro-organisms in the bio bed degrade the organic matter and take up nutrients. In addition to this, there are aquatic plants rooted in the upper part of the bio bed. The roots take up nutrients from the wastewater and also create a good environment for the microorganisms to thrive in.

After passing the bio bed, the water is led into the distribution well in the middle where it passes through another bio bed.
The outlet pipe is installed so that the effluent drains completely and no water is left standing in the pipeline. If water is left standing in the pipe there is a risk of freezing at low temperatures. To make sure that this doesn’t happen, a self-regulating heating cable is installed in the outlet from InterACT™ to eliminate the risk of freezing.

ReACT™ - additional phosphorus removal

In some cases additional phosphorus removal is required by the authorities. In that case Alnarp Cleanwater provides an extra treatment step, ReACT™, a lime material designed to adsorb phosphorus. When the material is exhausted it is an excellent fertilizer providing both phosphorus and lime to productive farmland. This results in a local, small-scale cycle of phosphorus since farmland and onsite wastewater treatment plants usually are located in the same area.

Technical components

ACT Natural™ contains the following technical components; water pump, air pump, a microcomputer and water level sensors.
The microcomputer controls and monitors the system. In case of an abnormality, it generates an alarm, the alarm lamp should be placed where it can be seen daily. The system is connected with an underground cable 5G1. 5 to 230 V e.g. in the dwelling house. To ensure that the alarm is activated in case of power failure due to a blown fuse, the alarm should be fed from an additional group in the main distribution box than the one feeding the microcomputer.