At this year's IFAT 2016, to be held between 30 May and 3 June 2016 in Munich, GEA will again be presenting new energy-efficient savings and optimization solutions for water and effluent treatment at its exhibition stand 427/526 in hall A1. For instance, the fully automatic control and regulating process GEA varipond®, which will be available for most of the waterMaster decanters in the GEA ecoforce series starting in 2016. This guarantees reliable, energy- and cost-efficient processing of sewage sludge with constant concentration even in conjunction with fluctuating feed conditions. A GEA innovation which will be appreciated particularly by the operators of municipal effluent treatment installations - not least also as a result of the retrofit version which can be retrofitted easily and cost-effectively.

Fully automatic: constant sludge dewatering even in conjunction with fluctuating feed conditions

2016.05.31 IFAT Varipond Drawing
Operation of the varipond® control in the decanter: The throttle plate, which can be shifted axially, is moved into the optimum position by means of intelligent sensors while the machine is running.

  • Patented control and regulating procedure also for waterMaster decanters in the GEA ecoforce series starting in 2016
  • Reliable, cost-saving pre-dewatering and thickening of primary and secondary sludge with constant concentration even in conjunction with fluctuating feed conditions
  • GEA innovation: Variable pond depth with automatic feed regulation while machine is running
  • Energy- and resource-efficient simplification of infrastructure and operation during start-up and shut-down procedures without liquid overflow to the solids side
  • Up to 30 percent reduction in energy input - increased service life of the installation
  • Retrofit version: Cost-efficient retrofitting option at any time

GEA varipond® does not leave operators of effluent treatment plants in the cold

Wherever sewage sludges have to be treated with centrifugal separating technology, it is essential to ensure a precise and reliable process even in conjunction with a wide range of conditions. GEA varipond® is a patented control and regulating process which ensures precise compliance with the requirement of constant concentration for downstream processes whenever decanters are used. “For instance, for the pre-dewatering and thickening of primary and secondary sludge in effluent treatment plants - in a scenario with which the operators are only too familiar: A sudden cloudburst, and the pumps and dewatering systems have to operate at full throttle in order to be able to cope with large volumes of water which is contaminated with solids”, says Joost Vliegen, Director Product Management Environmental Technology at GEA. “A system such as varipond® which provides an immediate response to the changed requirements ensures the necessary operational reliability in such situations.”

The GEA innovation: Variable pond depth while machines are still running

In the past, in order to ensure a constant concentration in conjunction with fluctuating feed conditions, decanters had to be shut down and manually converted. With varipond® (the name stands for "variable pond depth" in conjunction with machines which are still operating), the engineers of GEA have developed a process solution which automatically ensures optimum adjustment of the centrifuge to changed feed conditions while the machine is still operating. varipond® regulates the liquid level in the decanter bowl so precisely that the concentration of the thickened solids can be set to a constant level, and it is possible to ensure precise compliance with this requirement. Optical sensors measure the solids content of the thickened sludge, compare this figure with the defined setting, and the regulating facility ensures that the concentration remains constant - everything takes place automatically. This means that unsupervised operation is also possible at night and during the weekend.

Reduction of up to 30 percent in energy input - longer service life

Further advantages: With the variable pond depth, varipond® ensures simplified infrastructure and operation for starting up and shutting down the decanter without liquid overflowing to the solids side - utilizing the maximum g-volume of approx. 90 percent (g-volume = contents x bowl speed).

The installation of a solids scraper with piping which prevents sludge which has not yet been dewatered from entering the solids container, and flushing water for ingress water is no longer required. “By adjusting the g-force to the feed conditions and by attaining the associated speed reduction, it is possible to achieve savings of up to 30 percent in electrical power. In addition, the process of starting up and shutting down the installation becomes much more simple and cost-effective without a solids scraper”, says Joost Vliegen.

varipond® – how it works

Wherever the clarified liquid is discharged from the decanter bowl, there is an axially adjustable throttle valve which determines the gap width of the outlet aperture: Small gap, higher resistance, lower water discharge, higher liquid level. Intelligent sensor technology detects the throughput quantity which is required at a specific time, and regulates the gap width as a function of the desired liquid level in the decanter bowl, by moving the adjustable throttle valve to the optimum position while the machine is still operating. The varipond® process ensures a decanter infrastructure with a reduced number of parts, and also ensures optimum efficiency in conjunction with a considerable reduction in operating and maintenance costs. All downstream processes are thus also optimized.

Retrofit – retrofitting option available at all times

The varipond® control and regulating technology of GEA can easily be integrated in existing waterMaster decanters of the GEA ecoforce series. This means that varipond® offers the possibility of individually controllable efficiency gains for all areas of operations. “It is frequently the case that small investments have a tremendous knock-on effect - particularly in the longer term”, says Joost Vliegen. “The advantages for the operator are obvious: No need to purchase new decanters, no lengthy downtimes, no need for complete conversion. The retrofit option with varipond® enables the operator to achieve process and product optimizations which previously were only possible in conjunction with high levels of financial and labour-intensive investments.” 

Advantages at a glance

  • Automatic feed regulation while machine is still operating
  • Simplified infrastructure for ingress water during start-up and shut-down procedures
  • Energy- and resource-efficient start-up and shut-down procedures without liquid overflow on the solids side
  • Simple and precise pre-dewatering and thickening with stable discharge concentration
  • Accuracy of ± 0.3 % DM, infinitely adjustable
  • Thickening without polymers is possible 
  • Maximum throughput capacity of the decanter
  • Up to 30 percent savings in terms of energy
  • Optimization of all downstream processes
  • Reduction of transport and disposal costs
  • Low level of wear, long service life
  • Maintenance-free
  • Unsupervised operation also possible at night and during the weekend
  • Efficient retrofit option available at all times

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