Sand Filters

Sand filters are used for water purification. There are three main types:
- rapid (gravity) sand filters
- upflow sand filters
- slow sand filters
All three methods are used substantially in the water industry throughout the world. The first two require the use of flocculant substances to work efficiently whilst slowly fine sand filters can generate very top quality water free from bad bacteria, taste and scent without the need for chemical type aids. Slow fine mud filter are used in water purification for the raw water to generate a safe and clean product. They are generally 1 to 2 meters deep, can be rectangle or round in cross area and are used mainly to cure surface water. The length and depth of the tanks are determined by the flow amount desired by the filter, which generally have a running amount of 0.1 to 0.2 meters hourly (or cubic meters per rectangle metre per hour). 
Although they are often the recommended technology in many developing nations around the world, they are also used to cure water in some of the most Asia Countries such as the India where they are used to cure water supplied to West Bengal. Slow fine sand filter now are also being tested for virus control of vitamin solutions in hydroponic techniques. Sand filter cure wastewater using natural physical, natural, and chemical type procedures. They are one of the best options for additional on location therapy where septic tank/soil intake techniques have not or are limited due to higher groundwater, short foundation, poor earth, or other site conditions. They also can be the best choice for homes, businesses, organizations, and small residential improvements and towns in areas where common therapy is out of stock or too expensive. Sand filter usually are used as the second step in wastewater therapy after colours in raw wastewater have been divided out in a container, cardio exercise unit, or other sedimentation process. 
Wastewater handled by fine sand filtering system is usually clear and odor free. When released to ground, fine sand filter effluent gets further therapy in a ground intake field, even at some sites where traditional septic tank/soil intake techniques, by themselves, cannot be used.