The lack of centralized sanitation is an acute problem for a private house or cottage. It can be solved by installing an effective autonomous sewage system.
Modern autonomous systems for receiving and treating wastewater comply with all sanitary standards; they do not spoil the landscape of the site, do not exude odors, and do not require frequent sewage disposal. New generation models treat wastewater by 95 - 100% without requiring constant maintenance. Water after such high-quality cleaning can be used for irrigation, and sludge - for fertilizing the soil.
Which system to choose and in which case
The choice of an autonomous sewage system should be approached very responsibly, having studied the advantages and disadvantages of all options. It will not be superfluous to perform some mathematical calculations.
There are three models of autonomous sewage depending on the method of operation:
- Cesspools and storage septic tanks.
- Overflow septic tanks.
- Stations with deep biological treatment.
Volume of effluents
Cesspools and storage septic tanks, as a rule, have a small volume and quickly fill up. The volume of runoff water practically corresponds to the volume of water consumption, minus the water used for irrigation of the garden. Thus, if the monthly water consumption in the house is 10 cubic meters. m., and the volume of the cesspool - 5 cubic meters. m., sewage disposal will need to be carried out every 2 weeks.
The required volume of overflow septic tanks depends on the amount of water consumed by the family for 1 day. The volume of the septic tank should be 3 times the amount of daily sewage. On average, 1 person uses 200 liters of water per day. This means that a family of 4 people consumes 800 liters of water per day or 0.8 cubic meters. m. We increase this indicator three times and get the recommended septic tank volume of 2.4 cubic meters. m. It should be remembered that the receiver tank in the upper part has overflow in the second tank, so the total volume of the tank will be greater than the volume of three-day drains.
Experts recommend installing structures with a margin of up to 30%, since there may be unforeseen increases in water consumption associated with seasonality, the arrival of guests, and a change in the number of people living in the house.
If the daily water intake exceeds 10 cubic meters. m., it will be necessary to install a three-chamber septic tank to effectively treat such a quantity of effluents.
Lot size
In areas of a small area occupied by buildings or planted with trees, there may not be enough space for the installation of overflow septic tanks or stations with deep biological treatment. In addition, there is a list of permissible distances from neighboring sections (10 - 12 m), residential buildings (8 - 10 m), water supply (25 m) and gas pipes (5 m).
Tank material
Today, polymer containers are very popular due to their low cost and relatively low weight. However, when installing a polymer septic tank, it is necessary to perform its fastening in a quality manner, so that during the disposal process the empty and light tank does not rise.
Most often, when installing an autonomous sewer, concrete structures are used. It is extremely rare to give preference to metal containers, due to corrosion of the metal and a short service life. You can make a receiver with your own hands from a brick.
The cost of work and materials
A cesspool is the most budget option. Installation of more complex structures will cost several times more, because in addition to buying and delivering materials, it involves the work of special equipment and the involvement of qualified specialists.
Maintenance and care
The cesspool and pressurized storage will have to be pumped out regularly (monthly, and sometimes more often). Overflow septic tanks also require cleaning, but not more often than once a year. Only stations with deep biological treatment do not need such maintenance.
Cesspool
It is a well for the accumulation of effluents. It is suitable for a summer house or a country house, where water consumption is low and, moreover, for only a few months of the year. The size of the well depends on the number of people living in the house. Experts recommend not increasing the depth of the cesspool more than three meters, since a large layer of sediment at the bottom will reduce the cleaning efficiency.
Sanitary norms provide for 2 mandatory requirements for cesspools with a volume of effluent more than 1 cubic meter. m per day. This is tightness and the presence of the bottom so that the water does not go into the soil and the use of such pits was environmentally friendly.
The cesspool requires regular and fairly frequent cleaning, so you need to choose a place on the site that is convenient for unhindered access of the scavenger machine.
Sealed Drive
In fact, this is the same cesspool, but in an improved version. A sealed drive is a container into which drains from the house are discharged and stored until cleaning. When filling the drive, it is necessary to use the services of sewage disposal equipment and perform tank cleaning.
Two-chamber and three-chamber septic tank
For autonomous sewage of a private house, a two-chamber overflow septic tank is a good option. Its significant difference from previous options is that runoff accumulates in the first tank, settles, the sediment is fermented using anaerobic bacteria, and water, after partial purification by gravity, flows into the second tank without a bottom and drains into the soil.
Overflow septic tank can be three-chamber. In this case, the first two tanks serve for the accumulation and sedimentation of water, and drainage occurs from the third well. The more complex design of the three-chamber septic tank provides high-quality water purification, the cleaning coefficient can reach 70%. The overflow septic tank model also requires periodic cleaning, usually once a year. With the help of a scavenger, the sediment is purified from the first containers (one or two) in which water settles.
However, not every site can use such treatment facilities. It is inappropriate to install overflow septic tanks on clay soils and with a high level of groundwater occurrence. In the first case there will be no effective drainage, and in the second there will be a serious violation of sanitary standards.
Septic tank with a filtration field, a biological filter and aeration
Septic tank with deep biological treatment is an ultramodern model of autonomous sewage for a private house. The water purification coefficient reaches almost 100%, therefore, such a septic tank can be used, regardless of the depth of groundwater. A septic tank with biological treatment absolutely does not require sewage disposal. The only prerequisite is the connection to the mains, the station does not work without power.
During the treatment process, wastewater passes through several chambers (receiver, aeration tank, sedimentation tank and finishing section), each of which has its own function. The receiver serves for the accumulation of effluents and separation of fractions. In the aeration tank there is a process of fine bubble aeration. The jet pump (airlift) pumps water from the receiver into the aeration tank and actively saturates it with air. In aerotank aerobic bacteria trigger the decomposition of organic substances. The sump serves as a secondary treatment.
The heavy fractions settle to the bottom and form sludge, and the light is trapped and returned to the aeration tank for further treatment. The final section receives water, purified almost 100%, without color and odor.By gravity or with the help of a drainage pump, it is removed from the station to the filtration well, drainage ditch or to the filtration field. A typical filtration field is an underground construction of drainage pipes laid on a sand and gravel pad with natural fluid movement. It can be used for water purification and in the model of overflow septic tanks.
