Sludge treatment facilities
Silt thickeners
The activated sludge deposited in the secondary settling tanks has a high humidity. The main part of this sludge is fed back into the aeration tank. As a result of the development of microorganisms, the mass of activated sludge in the “aerotank-secondary sump” system continuously increases and the so-called excess sludge is formed, which is separated from the recirculating sludge and sent for further processing and dehydration.
It is unprofitable to process excess activated sludge with high humidity (99.2-99.6%), therefore it is pre-compacted in sludge thickeners. In the process of compaction, the humidity decreases and, consequently, the volume of excess sludge.
Excess activated sludge continuously enters the sludge thickener, where it gives off the bulk of free moisture in the form of interstitial water. Sludge from the sludge thickener is fed for further processing. The separated sludge water contains a significant amount of dissolved organic contaminants, so it is returned to the water treatment chain before the aerotanks.
The amount of excess sludge removed from the aerotanks is determined at the rate of 0.35 kg per 1 kg of removed BOD20 and is:
gle - BOD20 incoming flow, ;
— BOD20 treated waste,
— average daily wastewater consumption, .
Estimated consumption of excess sludge entering the sludge thickener:
where is the moisture content of the incoming sludge, ;
is the density of the incoming sludge, .
Required volume of sludge thickeners:
where is the duration of compaction, .
We accept 2 sludge thickeners in the form of wells with a diameter of 2 m.
The amount of compacted sludge is:
where is the moisture content of the incoming sludge, ;
is the moisture content of the compacted sludge, ;
- the amount of excess sludge removed from the aerotanks, ;
is the density of compacted sludge, .
The amount of water discharged from the sludge thickeners is:
The sludge water is discharged into the aeration tank. The release of compacted sludge is carried out under hydrostatic pressure on the sludge pads.
silt pads
Sludge beds are one of the first sewage sludge treatment facilities. Sludge beds are designed for natural dehydration of sludge generated at biological wastewater treatment plants. The use of these structures is explained by the simplicity of engineering support and ease of operation in comparison with filter presses, vacuum filters, and dryers.
The simplest and most common method of sludge dehydration is drying them on sludge beds with a natural base (with or without drainage), with settling and surface water drainage, and on sealing pads.
This project provides for silt pads on a natural base with drainage.
Silt pads consist of maps surrounded on all sides by rollers. The dimensions of the cards are determined based on the moisture content of the sediment, the method of cleaning after drying.
On the silt pads, roads with ramps are arranged for access to the maps of vehicles and mechanization.
The required usable area of sludge sites is:
where - compacted sludge, ;
is the load on the sludge beds, taken according to , ;
— climate coefficient, .
Additional area of silt pads occupied by rollers, roads, ditches:
where is a coefficient that takes into account the additional area from the usable. We accept.
Total area of silt pads
Sludge beds are checked for winter freezing:
where is the amount of compacted sludge, ;
— the duration of the freezing period: the number of days in a year with an average daily air temperature below -10°C; accepted;
— usable area of silt pads, m2;
- coefficient taking into account part of the area allocated for winter freezing: ;
- coefficient taking into account the decrease in sediment volume due to winter filtration and evaporation: .
We accept four cards with dimensions of 16x34 m each for the device.
The amount of dehydrated sludge with a moisture content of 70% removed from sludge sites:
where is the amount of compacted sludge, ;
is the moisture content of the compacted sludge, ;
is the moisture content of the dehydrated sludge, .
Dried sludge storage area
For storage of dehydrated sludge, an open area is provided, designed for 4-5 months of cake storage at a layer height of 1.5-2 m. Its area: . Dimensions in plan 10.5x21.5 m
Calculation of the chlorination plant
We accept a dose of chlorine for water disinfection Dchl= 3 g/m3. Chlorine consumption for 1 hour at maximum consumption
kg/h
Chlorine consumption per day
kg/day
The chlorination room provides for the installation of two LONII-100K chlorinators. One chlorinator is working, and the other is a backup.
Let's determine how many evaporator cylinders you need to have to ensure the resulting performance in 1 hour:
,
where is the output from one cylinder, kg/h; \u003d 2 kg / h (table 5.1) for cylinders located at an angle of 90o.
We accept cylinders with a capacity of 40 liters containing 50 kg of liquid chlorine.
We accept in this course project two independent installations for the evaporation of chlorine from cylinders and its dosing. One of them is a backup.
In accordance with the current regulations for the placement of equipment and chlorine in cylinders, it is planned to build a building consisting of two rooms: a chlorine dispensing room and a chlorine supply warehouse. The chlorine dosing room is equipped with two exits: one - through the vestibule and the second - directly outside (with all doors opening outwards). The consumable warehouse of chlorine is isolated from the chlorine-dispensing fire-resistant wall without openings.
Evaporator cylinders are stored in the chlorine service warehouse. To control the consumption of chlorine in the warehouse, two dial scales of the RP-500-G13 (m) brand are installed, on which five cylinders are placed. Each cylinder balance is part of two independent chlorine evaporation and dosing units, which operate intermittently.
In total, 60/50 = 1.2 cylinders will be used per day. Thus, at the moment the unit starts working, when 5 cylinders are installed on the scales, the chlorine supply will be sufficient to work for: 10/1.2=8.3 days.
When gas is produced from five cylinders on one scale, the chlorine supply will be sufficient to work for: 5 / 1.2 = 4.15 days.
In the chlorination room we place two LONII-100K chlorinators and two cylinders (mud collectors) with a capacity of 50 liters. Each chlorinator, cylinder (mud tank) and one scale with vaporizer cylinders, located in the consumable warehouse, form an independent technological scheme for evaporation and dosing of chlorine, which operates periodically.
The chlorine dosing station is provided with a supply of drinking-quality water with a pressure of at least 0.4 MPa and a flow rate of:
m3/h,
where is the rate of water consumption, m3 per 1 kg of chlorine, = 0.4 m3/kg.
Chlorine water for waste water disinfection is supplied in front of the mixer. We accept a mixer of the "Parshal tray" type with a neck width of 1200 mm.
Figure 5. Mixer type "Parshal's tray": 1. Inlet tray; 2. transition; 3. Chlorine water pipeline; 4. inlet socket; 5. neck; 6. outlet socket; 7. outlet tray; 8. target of complete mixing.
For a given flow rate, the dimensions of the mixer, m, will be:
A=1.73
D=1.68
H'=0.59
l'=7.4
b=1
B=1.2
E=1.7
H=0.63
l=11
C=1.3
HA=0.61
L=6.6
l”=13.97
To ensure the contact of chlorine with waste water, we will design contact tanks according to the type of horizontal settling tanks.
Tank volume:
, m3,
where T is the duration of contact of chlorine with waste water, T = 30 min.
, m3,
At a speed of movement of wastewater in contact tanks mm / m, the length of the tank L, m, will be:
m.
Cross-sectional area, m2, is equal to:
m2.
With a depth of H=2.6 m and a width of each section b=6 m, the number of sections:
The actual duration of contact of water with chlorine per hour of maximum water inflow:
h = 30.6 min.
Taking into account the time of water movement in the outlet trays, the actual duration of water contact with chlorine will be about 31 minutes.
We accept contact tanks developed by TsNIIEP of engineering equipment.They have a ribbed bottom, in the trays of which flush pipelines with nozzles are located, and aerators and perforated pipes are mounted along the longitudinal walls. The sediment is removed once every 5-7 days. When the section is turned off, the sediment is stirred up by technical water coming from the nozzles and returns to the beginning of the treatment plant. To keep the sediment in suspension, the mixture in the tank is aerated with compressed air at an intensity of 0.5 m3/(m2h).
To supply compressed air to the contact tanks, we accept two VK-12 blowers (one backup).
General information about the enterprise OOO Gazprom transgaz Ufa
Open Joint Stock Company Gazprom is the largest industrial association of the Russian Federation, one of the key sectors of the country's economy.
LLC Gazprom transgaz Ufa is part of the Gazprom Open Joint Stock Company, one of the largest enterprises in the fuel and energy complex of Bashkortostan, was founded in 1953. The first gas torch was lit on the Tuimazy-Ufa-Chernikovsk gas pipeline.
According to the results of activities in 2006 and 2007. OOO Gazprom transgaz Ufa was awarded an honorary diploma as the Best Industrial Company of the Republic of Bashkortostan.
The main activities of LLC Gazprom transgaz Ufa are: reliable gas supply to Russian consumers and ensuring gas supplies to countries near and far abroad under interstate and intergovernmental agreements.
To accomplish these tasks, the company carries out the following activities:
— ensures reliable and safe operation of gas facilities in the region;
- builds gas pipelines and other gas transportation facilities, as well as social and cultural facilities on the territory of the republic;
— protects the environment, rationally uses natural resources, uses environmentally friendly and energy-saving technologies in gas transportation;
– develops new technologies and mechanisms for the repair and construction of gas pipelines, conducts research, thematic and development work.
OOO Gazprom transgaz Ufa pays great attention to the environmental safety of operated facilities and the rational use of natural resources. The main principles of the enterprise's environmental policy are: — preservation of the natural environment in the zone of operation of facilities, reasonable and rational use of natural resources;
— preservation of the natural environment in the zone of operation of facilities, reasonable and rational use of natural resources;
— Ensuring environmental safety of construction and operation of facilities;
— health protection and environmental safety of personnel and the population in the places of economic activity;
— systematic improvement of the environmental situation in all branches of the Company, involvement of all personnel in environmental protection activities.
chlorination chamber
For ventilation of the chlorination room, a ventilation chamber is provided with a 12-fold air exchange per 1 hour, carried out by two centrifugal fans of the EVR-3 type with an A-32-41 electric motor. Ventilation is switched on 5-10 minutes before the entry of service personnel into the chlorination room and continues during the entire time the workers are in the room.
It is required to make technological and hydraulic calculations of sewage treatment facilities shown in fig. 7.1.
| Typical treatment plant with a capacity of 30-60 thousand mg per day 1 monorail; 2 warehouse of reagents; 3 - blower room; 4 - pumping station; 5 - coal |
Both in foreign and domestic practice, ozonation of water has recently begun to be used.
The full performance of water treatment facilities should ensure: useful water consumption, that is, its supply to all categories of consumers; water consumption for own needs of treatment facilities (mainly for washing filters, as well as for emptying during cleaning and subsequent washing of sedimentation tanks, clarifiers, reaction chambers, mixers, clean water tanks, for the needs of chlorination, ammonia plants and other costs of treatment facilities) and water consumption to replenish the fire water supply in the tanks.
The design solutions provide for automation and dispatching of the treatment facilities, which creates conditions for their normal operation. In the USSR, a lot of work has been done on the typification of facilities for the treatment of domestic wastewater. Standard designs have been developed for grids, sand traps, settling tanks, aerotanks, biofilters, contact tanks, chlorination and blower stations, digesters and auxiliary facilities. Details of treatment facilities are also typified: distribution chambers for settling tanks, trays, gates, etc. Many of these standard designs are widely used at biological stations designed for joint treatment of industrial and domestic wastewater. In addition, some facilities (for example, neutralization stations) intended for industrial wastewater treatment are typified.
Depending on the state of aggregation of chlorine or chlorine-containing reagents introduced into the water, the wastewater treatment technology and the instrumentation of the process are determined. If water is treated with gaseous chlorine or chlorine dioxide, the process is carried out in absorbers; if the reagents are in solution, they are fed into the mixer and then into the contact tank. Chlorination plants include storage facilities and dosing devices. Solution and supply tanks, mixers, reaction chambers, settling tanks and other facilities are also needed. The working solution of the reagent is usually prepared in the form of a 5% solution of active chlorine. For chlorination with gaseous chlorine, vacuum chlorinators with a chlorine capacity of 0.08-20 kg/h are most widely used.
