Stakeholder Workshop on Riverbank Filtration

The AquaNES project team and Budapest Waterworks organised a regional stakeholder workshop on riverbank filtration on 30 May 2018.

The workshop started with the welcome speech of the COO of Budapest Waterworks Ltd., Csörnyei Géza, followed by a short AquaNES presentation by Prof. Dr. Thomas Wintgens.

The technical part of the workshop consisted of four sessions presenting different aspects of riverbank filtration:

  • hydraulics in RBF
  • water quality issues of RBF, 
  • post-treatment options and
  • case studies for different challenges.

Participants gained insight into RBF hydraulics as concerns local circumstances such as aquifer thickness, hydraulic conductivity, redox conditions and sustainable filtration rates.  The AquaNES SIPHON tool was introduced. This design tool helps to optimize the number of wells for an maximum water discharge of a BF scheme.

The session on water quality issues highlighted the treatment capacity of the bank filtration for quality improve. The biofilm on the substrate is highly effective in removing ammonia and a variety of organic compounds, including some organic micropollutants.  Required travel times for nutrient and virus removal are site specific and might require 50 days. Protection of wells against contamination from flooding is key in maintaining this good quality and a low level of post-treatment.

Yet at some sites and during certain periods enhanced post-treatment might be required. Results from AquaNES demonstrations sites and the use of membranes was presented in the third session.

Particulary interesting were the reports from utilities about the rehabilitation of abstraction wells, the effect of river flow variations on operation and the challenges of planning new schemes. The Hungarian speakers shared their experience in riverbank filtration operation and the immense planning, logistics and financial challenge to maintain and rehabilitate a huge bankfiltration system as that in Budapest. Interventions will also be required in view of the declining water level of the Danube.

Experiences with the red mud accident in 2010 upstream in the catchment have shown that the buffer capacity of bank filtration sites can be a good protection against pollution peak loads.

Future challenges will arise from deepening of the river bed, bank erosion or well clogging due to clam settling.

This also included the appeal to consider risk assessment and risk management approaches. This helps ensuring the safe operation of bankfiltration sites under a broad range of hydraulic boundary conditions. An adapted monitoring shall be inherent part  of this.

A survey via follow-up questionnaire among the participants revealed that

  • for raw water quality
    • iron and manganese are frequent issues
    • microbial parameters, turbidity and nutrients are challenges as well
  • water quality analysis and risk assessment are high priority areas to receive info and training
  • hydrogeological characterisation and flow modelling are of high interest
  • future research needs are seen for
    • RBF removal efficiency of organic micropollutants and microbial contaminants
    • Improving energy efficiency of pumps and treatment units
  • Post-treatment with membranes is considered not particularly feasible or relevant, compared to well established processes such as UV or activated carbon filtration
  • Training courses for engineers and managers from water supply organisations about combined RBF and engineered systems (efficiency, costs, energy consumption) and organisation of visits to RBF demonstration sites with post-treatment are found most effective

Date and venue

30 May 2018

Budapest Waterworks Headquarter, Budapest, Hungary

>50 participants from water utilities, authorities and research


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