The “VFL” (Vertical Flow Labyrinth) is a modern type technology of wastewater treatment, with high treatment efficiency with biological removal and disinfection, low investment expenses, low operation costs and reuse of the treated water. The conventional activated sludge process wastewater treatment plants are suitable for major treatment facilities. An innovate type of packaged wastewater treatment plants has been used to the plant for small source od wastewater production, starting from a single family house and ending at small communities, with a full range of packaged, site-assembled and containerized wastewater treatment plants up to 750 PE. After treatment the water can be reused as service water or for universal irrigation The treatment technology is based on a continually operated modified activated sludge process. The biological reactor comprises of a non-aerated chamber, aerated chamber, small clarification chamber and an integrated retention chamber. The chambers are connected by internal circulation conduits. The non-aerated chamber is divided by a series of overflowed and under flowed baffles into compartments creating so called “Vertical Flow Labyrinth”. In the final chamber, a flow control device is incorporated, which enables the usage of the volume of the integrated retention chamber in all compartments and tanks of the plant during peak flows. The aeration and maintaining of the activated sludge in suspension within the aerated chamber is ensured by fine-bubble diffusers. Mixing, circulation and re-circulation of the activated sludge is provided by compressed air introduced by air pumps. The “bio clean filter” is a slow gravity, vertical flow sand filter with dosing of disinfection agent. The “bio clean filter” is coupled with the preceding biological reactor with “VFL” technology to form a complete unit.