Non-pressure block-modular continuous operation water treatment plant Crystall-DF

Crystall-DF is meant for surface water treatment in drinking and industrial water supply systems.

The distinctive feature of non-pressure continuous operation filters is the process where water treatment and filter regeneration occur simultaneously. This ensures constant operation mode and balanced load of technological equipment. Owing to it, the automation system is extremely simplified, quantity of valves and piping is minimized; there is no need in wash pumps. To minimize discharged wash water volumes, it is recommended to use thin-layer separators Crystall-L together with Crystall-DF.

from 3 to 100 000 m3/hour
Water loss for filter regeneration (together with Crystall-L)
1-2% of capacity
Basic filter dimensions
D, mm – from 640 to 2500
H, mm – from 3300 to 7700

The non-pressure block-modular continuous operation water treatment plant Crystall-DF is meant for treatment of natural water from surface and groundwater sources. The technology is based on non-pressure continuous operation sand filters.

The basic element of the plant is the filter-module Crystall-DF, which is a non-pressure open sand filter, where filtration and washing of the filter layer occur continuously and simultaneously. Therewith, the regeneration process can be stopped for several hours (for example, for maintenance of the compressed-air supply system) without deterioration of filtrate quality. The filter provides high standards of drinking water treatment and high efficiency of communal and industrial wastewater treatment.

Due to its extremely simple construction, the plant operates continuously, does not require constant maintenance service as well as application of intermediate tanks, pumps and valves and piping.

The filters are characterized by absence of undercarriage, which can wear down, and low energy consumption (only for feeding compressors of the bed regeneration system). As a result of continuous sand washing, occurring simultaneously with the filtration process, work stoppages (in normal mode) for filter washing do not occur. As the filter body is made of stainless steel, the filters can be used for a long period of time even in aggressive environment.

Filter operation management is limited to the necessity to control the amount of air supplied to the air-lift by means of the area flowmeter; filter maintenance service requires presence of maintenance staff only for a few minutes.    

Operation description

The operation principle of the self-washing sand filter is based on returnflow filtration. Raw (untreated) water is supplied to the filter by the supply pipe located in the upper part of the filter, and is uniformly distributed in the layer through the distributor (1), then passes through the bed layer in the upward direction. The treated filtrate is discharged through the discharge pipe (2). Dirty filter layers are transported by the air pump (4) from the bottom of the filter (3) to the water-air sand wash device (5). Using elevation difference of water table in the filter and in the wash device, treatment of the layer occurs due to sand washing by the clean filtrate coming from the bottom to the wash labyrinth. As a result of turbulence, separation of sand grains from suspension begins in the transport pipe and respective treatment and separation occur in the wash labyrinth (6). After washing, water is discharged outside by means of the water pipeline (7), at the same time, the treated filter sand falls on the upper part of the layer (8). Consequently, the sand layer is in constant motion downwards, and the processes of water treatment and sand washing are regular, simultaneous, do not require regulation.


  • minimum of valves and piping, no need in complex regulation systems;
  • small site area;
  • high durability of the filter layer: at normal filter operation, sand loss makes up about 0.2% per year;
  • low energy consumption: electrical energy is required only for feeding of the compressor, which provides work for airlifts;
  • low operating costs: in basic design, the filter is made of stainless steel and has no  undercarriage, which can wear down;
  • minimum maintenance service: simplicity of the process reduces operating time of  maintenance staff to a few minutes a day;
  • no stoppages when washing: simultaneous filtration and washing eliminate the necessity in  periodic filter operation;
  • no separate wash plants or devices, no additional wash pumps;
  • small amount of wash water;
  • no water losses for the “first filtrate”;
  • efficient and precise process control.