Poolking, your best swimming pool equipment manufacturer and supplier with more than 20 years experience.                                                                              +8613922334815

  • Product Details

Sand filters are an integral part of the water treatment industry. They act mysteriously, removing contaminants and filtered solid particles, thus providing safe drinking water. In this world of sand filters, however, comes a rich tapestry of different types, each with its own strengths and suitability to specific circumstances. The following article covers the three major types, gravity, pressure, and slow sand filters, as well as their features, advantages, limitation along with sand filter selection options.

1. Gravity Sand Filters

The gravity sand filters, in particular, make use of gravity. Water, being compelled by its density, flows through a very detailed drainage layout done on sand media that is carefully graded. Through this excursion, contaminants (e.g., sediments, turbidity, and even some microorganisms) get trapped inside the weaving space between the sand particles. This simple yet effective design offers several advantages:

· They are simple-designed, which makes them straightforward for functioning and maintenance. This is because their simplicity in the design reduces initial investment costs due to the complexity of the machinery.

· Gravity filters remove turbidity and suspended solids and return water to its natural state, which is crystal clear and clean. They are also suitable for systems with a constant water source and moderate levels of water contamination.

· Gravity filters are self-sufficient systems because they require minimal external energy input. They rely on the gravitational pull to constantly flow water, offering advantageous sustainability and cost-efficiency for places where electricity supply is a constrained resource.

However, gravity filters also come with limitations:

· They ought to have an elevated storage tank in a bid to create enough hydraulic heads for water flow. This can be a challenge in places where the available area for such purposes is seriously limited.

· Gravity filters are slower than other types because they usually work at slow flow rates. This means that this factor has to be considered when assessing the necessity of support.

· Gravity filters are known to be highly affected by water with high turbidity or a lot of microbes present. This is the main reason why gravity filters are ineffective.

2. Pressure Sand Filter

Pressure sand filters use an external pump that acts as the driving force, pressurizing the raw water and pushing it through the sand media. Similar to gravity filters, pressure filters capture contaminants within the sand bed. This method offers following advantages:

· Pressure filters replace elevated storage tanks, making them the best choice for sites with inadequate space. Their small placement may allow for more flexibility in terms of location.

· Pressure filters can handle higher flow rates compared to gravity filters. They also excel at treating water with higher turbidity levels, making them suitable for various applications.

· Pressure filters offer more flexibility in terms of influent water quality, demonstrating better tolerance for fluctuating turbidity levels.

However, pressure filters also have drawbacks:

· The permanent running of pumps equals higher operational expenses because of the continuous energy consumption.

· Pressure filters are more complex in their design than gravity filters. This might require experienced people to do maintenance tasks and troubleshooting.

3. Slow Sand Filters

Slow sand filters work on a principle-based entirely on another philosophy. Such filters operate at greatly slower velocities than their counterparts. This arrangement leads to biofilm formation on the sand bed, which is on the top part of the surface. Biofilm is composed of beneficial microorganisms and trapped organic matter, helping filtration. They have certain advantages:

· Slow sand filters are highly effective in removing bacteria and viruses, both of which threaten public health. The biofilm layer provides a biological barrier of immense specificity, reducing the microbial load of the treated water significantly.

· These types of filters feature an easy-to-assemble design and require little energy from the outside. This makes them environmentally friendly and sustainable, and they do not require further maintenance in these cases.

However, slow sand filters also have limitations:

· Since the very low flow rates make slow sand filters highly space-demanding, they require a big filtration area to attain the needed dosage. This is why they are not widely used for large-scale purposes in towns.

· Highly turbid influent water tends to easily clog up the high filtration rates of slow sand filters, which can demand regular maintenance. Pretreatment processes have to be implemented before the filtration steps so that the water quality stays uniform.

· Slow sand filters function properly if the top sand layer, which now contains the old biomaterial, is regularly removed. The amount of treatment required should be closely tested according to the influent water quality.

Choice of Suitable Sand Filter

Selecting the most suitable sand filter type requires careful consideration of several factors:

· The total number of suspended solids, microbiota, and the organic load of the source water directly affect the type of filter to be employed. For instance, pressure filters, due to their outstanding performance under high turbidity, are the best choice for this, while slow sand filters stand out as the most efficient among those efficient filters that remove pathogens.

· According to the required volume of treated water per unit of time, the specific filter size and type are suggested by the filter. Pressure treatment and gravity filters have much faster flow rates compared to the low flow velocities of slow sand filters.

· Gravity filters are the most practical option with low operational costs. However, they require more space than compact pressure filters, which have higher running costs. Moving bed sand filters are also costly and require a big initial investment.

· Gravity and pressure filters normally do not comprise the complexity of operation and maintenance that may be required for slow sand filters, which may demand adaptations according to source water quality and biological film management.

Each kind of sand filter is a 'specific' solution to a water treatment problem and has an 'indispensable' role in the water treatment. Gravity filters are suitable for situations where there is a constant water source, acceptable level of pollution and where moderate contamination of the water is present due to their scope and energy efficiency. Pressure filters, giant engines, and surprisingly damp sensitive ranges strike the right balance between flow rate and water quality. Slow sand filters, which are a marvel of biological functioning, are the ultimate pathogen removal players and a potentially new choice of chemical-free approach, but space is an important feature which must be well planned and managed. By determining the unique capacities and incapacities of all types, one can effectively pick the sand filter of choice for having clean and life-protected water, adapted to the needs of each application.

Basic Information
  • Year Established
  • Business Type
  • Country / Region
  • Main Industry
  • Main Products
  • Enterprise Legal Person
  • Total Employees
  • Annual Output Value
  • Export Market
  • Cooperated Customers

Send your inquiry

If you have any inquiry about our products, feel free to contact us that we are 24 hours on line.We've got preferential price and best-quality products for you.​​​​​​​


Send your inquiry

Choose a different language
Tiếng Việt
bahasa Indonesia
Current language:English