Biological Effluent Treatment

Development and optimisation of decentralised, plant-based water treatment systems for use in developing and industrialised countries

There is a global demand for a technology that makes communal waste water hygienic and that is easy to implement and safe to handle. Appropriate planning concepts and sizing approaches were developed to create a basis for using technologies close to nature for providing hygienic, purified water in the future. 



In emerging and developing countries, many people die because they use unpurified waste water for irrigation in agriculture. In industrialised countries, surface water and freshwater used for bathing must be protected from pollution. 

A research association has investigated to what extent ground filter technology could provide irrigation water according to national and international requirements. This sub-project also included molecular-biological investigations concerning the influence factors and mechanisms of germ reduction on a laboratory scale. In addition, plant-based water treatment systems were investigated with regard to the reduction of pathogenic or occasionally pathogenic micro-organisms and parasite states on a pilot and commercial scale. 


  • A combination of one vertical and one horizontal filter with specific substrate filling, an hydraulic load of 40 mm/d at the first stage and a freight of approx. 20 g CSB/m2*d were optimal with regard to high germ reduction performance and the prevention of colmation. 
  • Multi-step systems have a better E. coli germ reduction performance than single-step systems. This can mainly be explained by the fact that multi-step systems have a higher hydraulic efficiency, given the same hydraulic area load. 
  • The predatory activity of protozoa and bdellovibria seems to play a crucial role in germ reduction. Strategies for the optimisation of germ reduction in plant-based water treatment systems should be aimed at understanding and controlling these predatory activities better. 

More Project Informations

Project title:  Germ count reduction in waste water using plant-based water treatment systems: development and optimisation of decentralised, plant-based water treatment systems for use in developing and industrialised countries (Part 1)

Project number:  02WA0107

Project period:  01.11.2000 - 30.04.2004

Project contact:

Herr Dr. Müller

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Source: German National Library of Science and Technology Hannover (TIB)