Recycling system for domestic waste water treatment in rural areas

  1. Introduction

In Romania, most of the buildings in rural areas do not have the ability to connect to a centralized sewage system. Most of them have a toilet in the backyard, where WC is situated above holes in the ground. These are so-called latrines. When faeces are deposited there, soil and water are affected. If the house is supplied with a septic system anaerobic effluent treatment pollute the soil and the water. According to Council Directive 91/271 / EEC of 21 May 1991 concerning urban waste water treatment, as amended by Commission Directive 98/15 / EC on 27 February 1998 transposed into Romanian legislation by Government Decision no.188 / 2002 approving the rules the waste water discharge conditions in the aquatic environment, modified and completed by Government Decision no. 352/2005 for agglomerations with more than 2,000 more than 10,000 L. E. coastal, before being discharged into receiving waters, it is necessary to achieve “appropriate treatment” that take into account local conditions. Also, for all agglomerations with more than 2,000 that are located in hilly or mountainous areas, the geo-morphological and climatic require specific solutions and individual: sewage plants small natural treatment in lagoons or other methods of treatment unconventional. The system for the treatment and recycling of waste water using an aerobic digestion process using an invention. Simplicity technical solution creates the premise of obtaining low-cost production system. Unlike traditional septic system, aerobic digestion produces a high quality effluent that can irrigate the plants root across leaching field and collected but can be sterilized and used for surface irrigation.


  1. Description

The system consists of a circular tank and a drainage pipe that continues to the soil surface by a pipe absorption of air, due to chimney effect created by sewage pipe ventilation inside the building (STAS1795-87) or an outer pipe diameter larger than the pipe through which air is drawn. Drainage pipe that pierces the walls of the tank has on the bottom circumference, rectangular slots, paused at the base, thus creating a drain. Above the drainage pipe is the pipe waste water, discharge the drainage pipe. The system is located in a leaching field.

1. Absorption pipe 2. Drainage pipe with slots 3. Drain 4. Slots

5. Leaching field 6. Tank 7. Wastewater pipe


III. Operation

The process is continuous and consists of:

  1. Pre-mechanicaltreatment which fats and solids with a larger size than the slots fall in tank. In the fall of waste water entering in tank, the drainage pipe due to Coanda effect until the liquid seeps slots where water enters the drainage pipe flowing then drain pipe outside the pit drainage.

  2. Aeration through pipe absorption due chimney effect created sewerage pipe ventilation inside the building (STAS1795-87) or an outer pipe with larger diameter than the barrel of absolve, which ensures that the aerobic organisms soil digest organic waste from waste water.

  3. Disinfection is optional.

Liquid fats, due to molecular cohesion, trickle on the outside of the pipe in tank. Every overcoming the level pipe drainage of water inside the pit, and leaving it in the field percolation oils, fats and bodies organics are withheld due to viscosity or larger size than the slots drain pipes and macerated by stirring of waste water in fall. These are decomposed by aerobic microorganisms naturally activated by air pumped through the ventilation pipe of sewage. Digestive movement is amplified by aerobic microorganisms and organic matter due to the presence of increased turbulence pipes and vents to the ebb and flow of water. After decomposition, they enter the field of leaching to the drainage pipe drainage. Fields percolation water treatment achieved through two main processes:


-shallow water filtration underwent treatment by suspended solids are removed by retaining the bedrock pores. Since the suspended solids are retained both mineral and biological origin, that the filtration process removes superficial and a significant portion of the organic load of water subject to treatment;

-
aerobic digestion dissolved polluting load of the water subjected to the treatment by the dissolved organic matter (measured by BOD) and
ammonia cal and organic nitrogen is converted to a film-biological biochemical aerobic organisms that are formed on the surfaces of the granular material. Aeration within the granular layer is enhanced as the movement of the convection caused by infiltration of water through the granular media, and the air diffusion from the surface of the bed of granular material in the layers by adsorption on porous media they represent. Biochemical oxidation of organic material is accompanied by the development of the bacterial culture, i.e., thickening of the organic film. Recycling system for domestic waste water treatment in rural areas Biodegradation and disintegration of organic compounds is continued by aerobic microorganisms in the soil, the air sucked out further. If the ground base on which is built the bed infiltration is water, the bed infiltration is carried straight into the base without any isolation, while if the ground base on which the build bed infiltrating permeable then isolated infiltration bed to the floor base with a waterproof membrane. Value sizing founding leaching fields is approx. 1.5 m2 / e.p. The performance of the purification plant are obtained by infiltration-percolation fields are as follows:

- Reduction of BOD5 (below 25 mg / l) COD (below 90 mg / l), and suspended solids SS (below 30 mg / l) in the effluent from the plant;

- Virtual complete nitrification; -

- Denitrification limited, the values obtained are different depending on the type of plant, namely: reduction of the amount of nitrogen up to 40%.

- Reduction of phosphorus is relatively high (60-70%).

- Possibility of eliminating contamination with bacteria from feces, if there is a sufficient height of the layer of granular material if the filtration is carried out as evenly in the granular layer, with preferred routes (yield reduction up to 1000 times the number of fecal bacteria for every 1 m layer thickness of the granular material).

Treated water is absorbed finally in top and side layers of soil and plant transpiration eliminated by spraying and irrigation.

They are installed and operated without problems for almost two years, over a hundred pilot systems.