DESIGN AND OPERATION OF WASTE WATER TREATMENT PLANTS

DESIGN AND OPERATION OF WASTE WATER TREATMENT PLANTS Buket DOĞAN 21424732

1. Facility Settlement and Hydraulic Profile Purification Plant Components: A treatment plant consists mainly of the following main and auxiliary consists of units: • First and intermediate pumping stations • Girders, sand trap (oil trap if necessary) and current meters • Balancing and pre-sedimentation • Biological treatment units • Second settling and recirculation system • Advanced treatment (disinfection, reverse osmosis, etc. for water reuse), if necessary • Sludge thickening, conditioning and refining • Sludge dewatering / drying and disposal • Distribution structures, pipes and ducts • Control laboratories and service buildings

Settlement Units in a treatment plant, land requirement optimum, pipe length and elevation loads should be placed as minimum. When the plant is settled, the sludge and chemical easy transportation of goods, vehicle traffic, installation of electric cables, maintenance and repair principles should be taken into account.

Hydraulic Capacity The hydraulic capacities of the treatment units must be determined according to the maximum hourly and dayly run. The connection ducts and pipes must be sized according to the peak load for maximum floods. Grid and sand holders must be able to work at all speeds at constant speed; sluices and other suitable hydraulic control for speed control should be used. Biological treatment units are usually sized according to the expected average organic loads. There must be enough air space in these structures to prevent overflow. Depending on load loss, number of units, layout plan and intermediate pumping stations change.

2. Pump Stations Wastewater pumping stations are used in sewerage networks, at the entrance of the treatment plant and for the purpose of raising or recycling wastewater in the plant. The design of the pump station depends on the type of pump to be used (eg dry type, wet type, centrifugal and screw pumps).

3. Grids In all wastewater treatment plants, grids are used to protect the equipment in subsequent units. The grids are handled in three types: rough, medium and thin. Rough gratings are used for smaller than 400 m 3 / h and are cleaned by hand. Medium and fine gratings are used in larger installations and mechanically cleaned. The width of the grid channel is chosen to be a minimum of 0. 6 meters. It is desirable that the velocity in these channels should not exceed the maximum value of 1. 0 m / s and the minimum value should be less than 0. 3 m / s. These speeds are determined not to accumulate in the canal and to avoid passage of the items held in the grate. The load loss in the grids is normally 0. 15 -0. 30 meters. If the grids are not cleaned regularly, the load loss increases. The amount of the substance retained in the grids depends on the characteristics of the wastewater and the spacing of the grill bars.

4. Sand Holder A sand trap must be used before other treatment units. For small treatment plants with a discharge less than 400 m 3 / h, simple hand-held sand holders are made. Larger installations have more complex sand retainers with automatic sand cleaning mechanisms.

5. Oil and Grease In domestic wastewater treatment plants, oils normally float on the water in the primary sedimentation basin. For this reason, there is a foam and oil collecting system in the pre-settling pool. If industrial plants produce oily and petroleum wastes in accordance with their processes, it must be ensured that the oils are trapped at the source with oil traps. Oil traps should be made as close as possible to the main process units and avoid mixing of oils with other wastes. Significant oil and grease producing industries (food and soap industries, refineries) usually have an oil separator in their wastewater treatment plants.

6. Flotation Units For lighter materials, sometimes ventilated buoyancy units are used instead of standard gravity oil. Thus, detergent and similar wastes are also removed. There are three types of flotation systems. Air flotation: In this system, simple ventilation is made in the atmospheric pressure, and light particles and droplets of oil are floated. This system is preferred to wastewaters that produce foam. (such as the pharmaceutical and food industries). Dissolved air flotation: In this system, air is injected together with chemical substances. Some industries, such as the paper and edible oil industry, provide good results; it is not used much in domestic wastewater treatment. The high cost of the chemical substances and the necessary special mechanical components should also be taken into consideration. The practices of this system are limited to some industries. Vacuum flotation: In this system, the liquid is saturated with air at atmospheric pressure and discharged from the reactor under vacuum.

7. Balancing Tanks If the wastewater treatment plant also comes with industrial wastes, a balancing tank is usually required. • Balance changes and concentrations • Assist self-neutralization • To avoid the effects of sudden waste discharges in some processes

8. Precipitation Preliminary sedimentation of domestic wastewater treatment is simple settlement without using chemical substance. However, in the treatment of some industrial wastewaters chemical substances may also be added during precipitation. In both cases, coarse sedimentation occurs.

9. Second Stage or Last Precipitation Pools The sedimentation in the second or final sedimentation tanks is stratified and disrupted. Sedimentation tanks should be designed according to these considerations. Layered precipitation occurs after a certain concentration. Some operational problems encountered in the activated sludge process are due to poor sedimentation of biological factors. Final settling tanks should be designed with both rinsing and mud condensation functions in mind. A cost optimization approach can be made for this. By increasing the amount of recirculation, activated sludge ventilation the volume of the pool can be reduced. However, in this case, the size and cost will increase as the solids load in the final settling pool increases. For this reason, it is necessary to approach the subject as a whole.

10. Mud Dewatering and Disposal Some excess sludge forms in all biological wastewater treatment processes. Sludge disposal, in some cases, causes hygiene and cost problems. In facultative ventilated lagoons and algae (stabilization) pools, excess sludge is deposited in the unit and removed every few years. The mud taken from the unit is usually left to natural dry and after drying it is used as a fertilizer or land filler. Since the excess slurry obtained from the long-ventilated processes is sufficiently stabilized, the slurry is directly condensed and then disposed of. Activated sludge and dripping filter sludges are introduced into the sludge digester and more stabilization is ensured. Only after this process the sludge is dewatered.

11. Power Needs for Operation in Treatment Plants The power requirement of a wastewater treatment plant can be calculated in two ways: • Installed power (in horsepower or k. W) • Power used (in k. W-hour) The installed power is found by collecting the power needs of each unit in the system. The power required for operation is calculated by multiplying the daily operating time (hours) of each unit by the installed power.

12. Staff The number of personnel required for a treatment facility depends on the type and size of the facility. The business manager can be an environmental engineer. For a successful business, different disciplines are needed. Operators often need to be experts in machinery or electrical. In addition, a sufficient number of assistants are required. All personnel work shifts during the day. The operation of the treatment plants by the private sector can be more economical and usually takes this route. However, there should be an oversight authority in the private sector that operates to check whether it meets the environmental and discharge requirements.

13. Some Building Constructions • The contractor (contractor) must be experienced in water-holding concrete structures. A water-holding concrete structure should be constructed from the beginning. • Open channels with liquid depth less than 1 meter and distributions can be made with local brick or stone materials. • Pipes that connect the units together should usually be buried. • A rainwater drainage system should be planned to prevent surface waters from entering the units and pumping stations during rainfall. • If a drip filter is to be used, it should be acceptable and should be selected as suitable stone media (or plastic media).

• In classical activated sludge and long ventilated installations, ventilation equipment must be installed to provide equal air / oxygen and protected against corrosion. • The placement of the bottom drains in the sludge drying beds, the properties of the gravel bed material and the depths should be described in the specification. • If necessary, there should be a bottom discharge system for each unit to be easily emptied. • For ease of operation, the units must be designed and built to be bypassed.

14. Some Mechanical / Electrical Considerations The mechanical and electrical equipment of the treatment plant must be suitable for the climatic conditions and the main electrical installation of the area where the plant is located. In selecting engines and stratters, the following rules are generally applied. • Up to 100 hp squirrel cage induction motors, 150 hp for greater power, the sliding ring motors are selected. Engine covers are made according to local conditions. • The starters depend on the type and size of the motor. • The cables must be PVC coated. The cables on the outside must be placed in the cable ducts. These channels should be at least 1 meter deep and marking their location.

• There should be a control panel in the control room. • For all outboard motors, a second control button must be provided separately from the control panel. • The factor of 1. 75 should be applied for general purposes and the factor of 2. 0 for aerators should be applied in decelerators. • 50 -100 lux lighting should be provided in the general lighting area.

15. Operation of a New Treatment Plant A newly constructed treatment plant is operated step by step. These steps are: • Dry running • Age working • Fully inactivation • Performance tests

All mechanical parts are primarily run dry individually. The aim is to make sure that all my mechanical parts work. The inlets, outlets and other units are then checked for leaks by filling with water. Finally, the facility to receive the wastewater is taken to normal operation (initially diluted wastewater can be supplied). During this time, pumps, ventilators and recirculation equipment (briefly all equipment) are introduced. The plant sometimes has problems when it comes to hydraulic, organic or even toxic shock loads. This is either checked at source, or balancing / neutralizing operations are applied. More than three times the normal hydraulic and organic load, usually "shock load" for 0. 5 -2 hours. After the plant is commissioned, performance tests are started. At this stage various samples are taken and analyzes are made.

16. Routine Operation Principles of Facilities • Keeping performance records: Keeping performance records allows you to evaluate the performance of the plant. By saving energy, chemicals and other cost elements, the possibilities of reducing operating costs can be searched. • Preventive maintenance: The purpose of preventive maintenance is to provide minimum interruption during operation. This is because a failure of a unit of the wastewater treatment plant may require that the unit be discharged by-pass and taken back to operation after the fault has been rectified. These are all expensive operations. Some spare parts and chemical substances should be backed up. Maintenance should be done regularly.

• Business handbook: Usually a business handbook is prepared by the projector and the construction company. The following points should be included in this booklet: - Operating principles and test charts - Principles of preventive maintenance - Record keeping • Control laboratory: The laboratory plays a key role in the operation of the treatment plant. Sometimes quality control is required. Even without a serious check, the BOD test for the sample can yield 100% different results. • Training: Operator training should not be overdone. On-the-job training is not enough; in practice this is the only form of training.

17. (Common) Wastewater Treatment Facilities Instead of making separate treatment plants for many small industrial plants, a common wastewater treatment plant (OAT) can be built which will cover all of these plants. The wastewater of the surrounding households and sewage workers can also be treated in the common wastewater treatment plant. Non-industrial wastewater can be beneficial because it provides vaccines and nutrients for biological treatment. It is better to make an economical-scale central treatment plant instead of separately treating small-scale industrial treatment plants. In this way, the incoming wastewater is balanced and self-neutralized. Thus, there is no need for a large number of operating personnel.

18. Seamlessly Business Principles • The number of pump stations should be kept to a minimum. Avoid pumping stations wherever possible. • Ventilation must be provided to the pump stations and wet reservoirs for safety reasons. • Groundwater level should be taken into consideration and precautions should be taken against the lifting force of the water in all deep structures. • Weak stairs and walking platforms should not be used. • To facilitate repairs, a minimum of two pumps, two aerators and two parallel sections must be provided. • Spare parts inventory should be reduced as much as possible.

• Alarms and preventive instruments are not mixed, but on the contrary must be understandable and simple. • Electronic equipment, switches and cables must be easily accessible. For automatic valves, pneumatic or hydraulic systems should be preferred instead of electricity. • In the direction of the collaborative principle, the wastewater pumps and the chemical dosing pumps must be associated with each other. • In case of unexpected corrosion, the following precautions should be taken. -Pipe wall thicknesses must be selected as required; If necessary, concrete coating should be done. -Durable materials must be selected. -Epoxy and other coating materials should be used. -Cathodic protection against galvanic corrosion.

• The long duration of sedimentation in sedimentation tanks and wet volumes causes the formation of anaerobic conditions (bad smell, corrosion, etc. ). • Ventilation device types must be selected carefully. • In the pool and lagoon constructions floor compression, suitable slopes and sheds are made. • Seepage of sewage water into the sewer system should be avoided. • Leakage leads to (1) increasing the flux, (2) increasing salinity, and (3) diluting the wastewater character. • Proper maintenance and operation must be provided.