Small water and wastewater systems, decentralised systems for water supply and wastewater treatment and their association with receiving bodies and industrial wastewater systems came into focus. Small systems are taken to be those serving from a few persons up to 4000 population equivalent. This range encompasses many industrial water and wastewater systems can be included as small systems. Associated with the size and the resources for operation and maintenance, there is in many countries a lack of qualified personnel to provide the expertise for the optimal operation conditions. This is why small systems represent a challenge for small communities or industry to achieve the effluent values imposed by the regulations. Therefore the small systems must deal with a wide variety of knowledge topics from basic concepts of physics, chemistry, biochemistry and microbiology through the fundamentals of process engineering, to design practices and operational matters. Training of personnel is one of the most important keys to successful operation of the systems.
With the topics decentralised wastewater collection and treatment systems, ecological sanitation, industrial wastewater treatment, anaerobic treatment systems, upgrading wastewater treatment systems, environmental management systems, environmental microbiology and population dynamics, operation and monitoring wastewater treatment systems, wastewater reclamation and reuse, low tech/appropriate systems, sludge management, biofilm reactors, sequencing batch reactors, nutrient removal and recovery, wetland systems and stabilization ponds. 147 papers were submitted to the conference secretariat, 78 were selected for oral presentation and 19 as posters. After the conference 33 papers were selected to be printed in this issue of Water Science and Technology.