Filtration pond rehabilitation work at water purification plant

Cleaning and particle size adjustment of filter media

Pollutants related to filter media are roughly classified into [adherent substances] represented by SS　and turbidity　and [adherent substances] represented by manganese　and aluminum. Of these, [adherent substances] can be removed by relatively light cleaning of the filter material, but it is difficult to remove [adhesive substances] that are coated on the filter material due to chemical action. Therefore, we have independently devised a filter media cleaning device [Sand Actor] that enables the [adhesives] to be satisfactorily peeled off from the filter media without reducing the effective diameter of the filter media. The total rehabilitation work system, which adjusts the particle size (adjustment of effective diameter　and uniformity coefficient) along with the finish rinsing of the filter media, was named [Sand Reverse System],　and it has become possible to carry out the work efficiently by continuous processing.

This method not only saves money compared to using a new filter medium, but also reduces the environmental load by effectively using natural resources, meeting the needs of customers who have acquired ISO14000 series certification.

Features

We manufacture and sell not only filter media but also equipment such as chemical injection pumps　and water quality measuring instruments. From that experience, we design　and manufacture not only filtration equipment but also various water treatment unit equipment. We will propose the optimum process based on many years of experience in order to realize the water treatment desired by the customer.

Basic principle of filter media cleaning device [Sand Actor (PAT.Pend)]

Flow of sand reverse system type filter material rehabilitation work

1.Pre-construction survey
■Filter material contamination survey Investigate the contamination status of the filtered sand during use according to the JWWA water filter media sand test method “Appendix I, Test method for filtered sand　and anthracite in use”. This value will be the basic data for future filtration pond operation management. This number sets the cleaning strength of the sand reverse.
■Filter layer thickness survey Investigate the current filter layer thickness　and gravel layer non-landing conditions,　and use it to determine the risk of deterioration of treated water quality　and outflow of filter media. The non-landing of the gravel layer is a phenomenon that directly affects the filtered sand layer, which is the heart of filtration,　and it is a content that should be grasped from the viewpoint of water quality management. Also prepares a report so that the current situation can be easily understood.
2.Rehabilitation work
■Carrying out filter media The filter material is taken out from the filter pond. Depending on the site conditions　and purpose, it will be carried out by a belt conveyor, a powerful suction vehicle, a jet ejector, etc. At our company, skilled workers perform the work carefully, which leads to the discovery of abnormal parts that cannot be grasped by the filter layer thickness inspection.
■Filter media cleaning　and sieving Clean to the desired value with the sand reverse. If you wish, we will adjust the particle size. If there are restrictions on the acceptance of wastewater, use a combination of wastewater treatment plants.
■Cleaning　and repair of the inside of the filtration pond We clean, repair　and paint the walls, water collection parts, pressure chambers, etc. inside the filtration pond. * It is recommended to repair the water collection part, etc., which can be seen only when the entire amount of filter media is carried out, at the same time as the rehabilitation work. * At our company, skilled special workers will properly construct the parts that need repair.
■Filter material filling　and leveling Skilled workers carefully fill　and level the filling with a crane, jet water jet, belt conveyor, etc. according to the design value. * This work requires special expertise,　and it is important to work carefully because each gravel layer is thin.
3.Post-construction survey
In order to understand the condition of the filter material　and the condition of the filter layer thickness after the construction, we will conduct the same survey as before the construction. * This survey can be compared with the state before construction, which can be useful for future operation management.

Comparison test results for filtered sand in use

	Cleaning turbidity	Hydrochloric acid solubility	Effective diameter	Equal coefficient	Remarks
Pre-rehabilitation filtered sand (dirty sand)	800 degrees	4.5%	0.62mm	1.33	–
Conventional cleaning sand	100 degrees	3.0%	0.62mm	1.38	Throughput 2.5m3/h
Sandactor® type cleaning sand	14 degrees	2.1%	0.62mm	1.32	Throughput 5m3/h

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