Suitability of Different Biological Sewage Treatment Systems

Small wastewater treatment plants suffer from higher specific peak loads and less qualified operational services. Therefore, small plants need special rules for design, construction and operation on the basis: the smaller, the less sophisticated - the less sophisticated, the better! Advantages and disadvantages as well as process stabilities of activated sludge plants with long time aeration, trickling filters, rotating bio-contactors and different pond systems are described and compared to each other. Technical plants should be preferred for serving housing estates when separate sewerages exist. Ponds are a favourable solution for villages with combined sewerages, especially such in rural areas. Emergent hydrophyte treatment systems (reed beds) are considered as still being under development. Practice proves that newly developed, highly sophisticated technical systems tend toward simplification, and small reaction volumes or areas are increasing when applied under practical conditions.