Septic tank is an applicable and simple equipment used for sanitary wastewater treatment. Septic tanks are often made of one or more waterproof enclosures made of concrete, fiberglass, PVC or plastic with a volume between 4000 and 7500 liters. In special circumstances, for volumes up to 1000 cubic meters, cumulative packages of smaller tanks are used. Septic Tank is an on-site equipment that reduces the organic matter and solids through depositional and anaerobic processes, but the goal of this equipment is not the complete treatment. For this reason, this process is often used in areas not connected to the main sewage, such as rural areas. The liquid from the septic tank is removed from the septic tank where it is refined at this location, but this may cause surface water pollution. The sewage will be refined to some extent at the exit from the septic tank, but the effluent of septic tanks sometimes may cause surface water pollution. Septic tanks are often made of one or more waterproof enclosures made of concrete, fiberglass, PVC or plastic.
In general, septic tanks have the following uses in the sewage treatment industry:
1. Primary purification of residential units, commercial units such as hotels and restaurants, or some industrial units known as pre-treatment.
2. Removing insoluble solids or fats in some projects where the amount of produced wastewater is low and requires low cost and simple cleaning at the site and does not have the required work space for advanced systems.
3. Pre-treatment as an initial sedimentation and initialization system in some sewage treatment plants that do not have the potential to dug sedimentation pools due to environmental conditions.
Installation and maintenance requirements
The place of septic discharge generally does not require maintenance and only the following should be taken care of:
1. Do not transport with vehicles on the discharge site.
2. 2. From planting trees around septic tanks be avoided because it can be an obstacle to the growth of tree roots. The minimum acceptable distance to plant a tree is 30 meters.
3. Do not cover the area with concrete or asphalt. Grass is the best cover because it eliminates excess water in addition to preventing erosion and corrosion.
4. The flow of water and sewage from the roof, patio or other places to the septic tank should be prevented.
5. If strong chemicals are used too much, the microorganisms in the tank are killed and the removal efficiency goes down.
6. Do not throw away anything that might cause pipe clogging. Avoid pouring greasy materials since they may block the discharge of liquid into the soil.
The unpleasant smell is not always the first sign of a faulty septic system. In case of observing one of the following signs contact an expert:
• The sewage returns to the household drainage place.
• The grass on the drainage area is bright green or spongy even when the air is dry.
• Muddy soil or water is accumulated around the septic system or the basement of the house.
• Very bad odor is felt around the septic tank or septic drainage.
In septic tanks embedded around the world, its life varies from 20 to 40 years. This device can be used as long as proper storage of the septic tank is maintained. Also, homeopathic systems should be checked at least every three years.