A magnetic backflow valve for discharging water quickly from a tank (e.g. a reservoir, vertical shaft) upon reaching a defined surface level has been invented by a young scientist at the Institute of Landscape Water Management at BUT Faculty of Civil Engineering, Ing. Michal Kriška, PhD. The device represents a simple and cost-effective design for an automatic discharging system. Such design is necessary for the reliable functioning of newly developed types of vertical root-zone wastewater treatment plants and pulse-emptied horizontal root-zone treatment plants. Moreover, it will also find use in all types of wastewater cleaning by filtration, in small power stations, in connection with the installation of small pumps and wherever an irregular increase in flow-rate is needed (e.g. garden ponds).
Nowadays, everybody has probably heard about root-zone wastewater treatment plants, and we can all quickly guess that it involves water filtration through a gravel material on the surface of which grow wetland plants Those who are more familiar with the issue know of the low cleaning efficiency of such systems. However, if this newly-invented device for pulse control is used in a root-zone treatment plant, the efficiency of such plant increases to 93 – 98% in most of monitored parameters.
The advantage of using this invention consists not only in how much the cleaning efficiency of the systems of root-zone treatment plants is improved, but also in the minimal operating costs – the device works without having to be connected to the power supply, it does not require an operator, it is made of durable materials and long-term, trouble-free operation is expected, an expectation supported by (among other pieces of evidence) the results of several pilot plant trials.
The device is comprises a magnetically closed backflow valve connected to a short draining tube. A permanent magnet is fitted to the valve gate and this is attracted to a second magnet fitted to the drainage tube. When the level of the water surface is increased, the backflow valve is shut and is sufficiently tight thanks to the magnets, even when the surface level is low. On the outside edge of the backflow valve is a mounting bracket, onto which a float link is fixed. (See Figure 1).
During a gradual rise in the water level in a tank, up until just under the level of the main float, the valve is closed. At the moment the surface reaches the level of the float, the magnetic and hydrostatic forces of the closed valve are overcome by the lifting force and the float is rapidly lifted up to the surface. At the same time, the link ensures that the solid body, consisting of the bracket fixing, backflow valve and magnet, is turned. The subsequent separation of the magnets results in the opening of the backflow valve. The opening of the backflow valve gate at the same moment causes a gradual drop in water level in the tank. So that the backflow valve is not inadvertently closed before the complete emptying to the minimum surface level, the body of the float is fitted to the body consisting of the backflow valve, magnet and bracket fixing, and ensures the floating of the backflow valve gate so that the water can drain out of the tank for as long as possible.
All metal parts (bracket for the permanent magnet, magnets, bracket and link) are either made of corrosion resistant materials or are surface-protected with a coating of epoxy resin.
The invention, which arose as a result of project TAČR No.TA02021032 – “Anaerobic separator of non-dissolved substances and nutrients”, is protected as a Czech utility model. Currently, BUT has a licence agreement concluded with the company ASIO, spol. s r.o., which is the first company to place a device of such a type on the Czech market. Once the efficiency of the device becomes known to the relevant professionals, wide usage in all newly realised root-zone treatment plants in the Czech Republic can be expected, and such plants will thereafter offer real competition to conventional wastewater treatment plants.
With contribution by Ing. Jana Hodná
