Introducing Residential Sewage Treatment System
For implementation of water treatment and recycling processes, and using urban and industrial sewages, suitable and useful methods will be used for operation. This colorless liquid is one of the purest materials on the earth and also one of the most complex solutions. Until recent two decades, energy is the most important national capital of countries but it is better to say that in near future, water will be national capital of countries.
Therefore, it will attracted industry, nation, government and all elements of a country. Regarding the population increasing trend in the large cities which automatically increases urban wastewater, it is necessary to form an urban sewage collection and treatment system. Since cost of designing, operating and maintaining sewage collection systems is high, here, we briefly overview the sewage treatment packages and returning it to water system. The purpose here is introducing sewage treatment package of Pars Ethylene Kish.
Sewage treatment methods.
Basics of treating sewage and polluted waters is the basis for separating polluting materials form sewage. Based on this, regarding the type of pollution, sewage pollutions can:
1. Physical: color, temperature, suspended material, foam and radioactive materials.
2. Chemical: minerals and organic materials.
3. Biological: bacteria and virus.
4. Physiological: taste and smell in soluble and insoluble forms.
After determining the type of sewage pollution, the next step is identifying all optimal treatment methods for sewage. Sewage treatment methods are very diverse but all treatment methods include three steps for eliminating pollutants. A brief explanation of these steps are presented below.
Initial sewage treatment
Initial treatment or initial step which is done for eliminating sewage physical pollutants. Steps that sewage passes to biological treatment step are called initial step. During these steps, suspended and floating particles of sewage will eliminate.
Initial sewage treatment steps include following cases
1. Screening for removal of floating and coarse particles like paper, fabric, wood, leaf, plastic, etc.
2. Grit chambering for removal of grains and heavy materials in sewage (oil and lipid) which are less concerned in urban wastewater treatment plants, but in industrial sewages, including oil industry ad refinery, a separate step will be used.
3. Initial deposition for removal of solid deposable materials (human defaces, food wastes, etc.).
4.Balancing or homogenizing for wastewaters which have variable flow or concentration is done for removal of impact loads. Neutralizing is done for regulating pH of strong acid or base sewages which in the case of industrial sewages, balancing and neutralizing are done concurrently.
5. Second phase or biological treatment which is done for removing the major part of soluble organic materials in wastewater (BOD & COD). Generally, biologic treatment processes are done by using biologic filters or aeration tanks, active sludge process and anaerobic tanks. In this step, microorganisms which decompose organic materials are used.
6. Third step treatment is used for clarifying, disinfecting and removal of nitrogen and phosphor from treated sewage during reuse.
Disinfection step is very important due to the presence of harmful bacteria like pathogens, parasite eggs and harmful microorganisms. Different methods are used for disinfecting the wastewater of second treatment step, including:
- disinfection by help of chemical materials including chlorine and its derivatives, oxygen peroxide, etc.
- disinfection by help of physical factors including warmth, light, UV, sound wave and disinfection by help of mechanical factors, disinfection by radiation like electromagnetic ray, acoustic ray, gamma ray and charged particles. According to above-mentioned, one of the common methods for sewage treatment is SBR method which will be explained in following.
Pars Ethylene Kish experts, in the design and fabrication steps of these packages, have always considered ease of use and elimination of complex mechanical and electronic equipment and also reduction of energy use as the basics of design and need to these packages. The product with these features can be easily used for low volume and residential consumptions and by having modularity capacity of tanks, we can use polypropylene tanks for wastewater treatment to volume 324m. Among advantages of the products of this company, we can refer to using advanced control kit for managing and guiding the system and using airlift technique for transferring sewage and sludge.
SBR process steps in sewage treatment packages of Pars Ethylene Kish
In treatment with SBR method, two pools are needed that the first pond is the place of deposition and collection of the sludge and second pond is aeration reactor or SBR.
Treatment cycle in SBR technique occurs in five steps which we will present in following.
First phase : filling and initial deposition phase
In the first step, sewage enters into first pond gravimetrically and after passing time of initial deposition, it transfers with airlift technique to secondary pool. This operation can be called initial clarification.
Second step : aeration phase
Sewage in the secondary pond is aerated and aerobic microorganisms activate and biological treatment phase begin. Volume of sewage which transfers from first to second pond is same in all cycles that this operation is called balancing.
Third step : rest phase
Secondary clarification operation is done in this phase and in secondary pond such that after ending aeration operation during determined time, sludge of aerobic treatment process deposits and actually treatment ends in this step.
Fourth step : discharge phase
Obtained wastewater after deposition of sludge in the bottom of tank, which is free from polluted materials and is smooth and odorless, exits gravimetrically.
Fifth step : sludge return phase
After discharging the wastewater, sludge deposited in the secondary pond transfers to initial pond and it is used as active sludge for completing anaerobic treatment operation.
Sewage treatment package advantages of Pars Ethylene Kish
1. Easy and rapid installation
2. Low risk caused by package defect
3. Sealed tanks
4. Energy step consumption
5. Non-occupation of space on the ground
6. Easy transportation capability and replacement possibility
7. Implementation in different climatic conditions
8. Lack of need to sewage collection and transmission pipelines.
9. Compatibility with environment and resistance against corrosion
10. Operation in low load conditions or shock caused by sudden increase in input volume.
11. Not needing periodical changes.
12. Not needing operator
13. Not needing raw sewage pump station
14. Not needing skilled repair technician
15. Not emitting sewage odor and pollution in the environment
16. System safety in terms of electrocution
Treatment efficiency of polypropylene packages and standards
Wastewater treatment package of Pars Ethylene Kish reduces COD and BODs of sewage to %94. Wastewater is odorless and without smell and level of its qualitative parameters is higher than Iran environmental standards and this wastewater can be used for irrigating green space, washing roads, parking and also in flash tanks, fire-fighting tanks and etc. and in the case of not needing, discharge it directly into the river, sea of absorption well without complementary treatment operation.
Following table presents results of experiments done on the output wastewater of sewage treatment packages of Pars Ethylene Kish which are done by wastewater technology and experiment institution in Achene in Germany.
Equipment used in the single-tank polypropylene package
Sewage treatment system of Pars Ethylene Kish is formed from three following sections :
1. Two-piece polypropylene tank corresponding with sewage input size: in these packages, one or several polypropylene packages with different sizes are used. Because SBR method needs two pools, in single-tank system, two pools form by using a baffle. In larger systems, tanks are connected in consecutive form and each tank is a pool. These tanks are resistant against corrosion.
2. Control panel box: control panel is consisted for an electronic smart kit for managing and navigating system and one compressor for aeration which are produced in in-door and out-door types.
3. Aeration diffuser and pump mechanism: sewage and sludge transfer operation between pools occurs by a pump mechanism which is designed by air lift technique. Along with this mechanism, there is one or several aeration diffusers that their role is transforming air flow to tiny bubbles and their distribution on the bottom of pools and activating microorganisms. Transferring air from control panel to this mechanisms id done by four plastic hoses and all parts of this mechanism are resistant against corrosion.
As referred in efficiency item, all parameters related to the treated wastewater of sewage treatment system of Pars Ethylene Kish contain environmental standards. But if we want to increase its quality, we should use adjunct treatment options.
Removal of nitrogen (D+) : for removing nitrogen, by adding this option, total N reduces to 25mg/l.
Disinfection (H+) : for disinfection: the best method for killing microbes and microorganisms without using chemicals like choler is using UV ray and this method is used based on the instruction of European Union for wastewater disinfection.
Phosphate removal (P+) : for removing phosphate: phosphate in wastewater helps the growth of algae and by adding +P option, we can remove phosphate from wastewater.
Convenience package (+K) : for easy and rapid control of package: in this option, pressure sensors are located and also settings for holidays (stoppings input flow) and reading function times and system errors with this option can be easily done.
Remote transmission (R+) :for controlling from remote distance: by adding this option, all information of machine including function times and etc. send to telephone and network. By adding this possibility, package Graf can be monitored from remote distances easily and reduce costs of inspection.
Polypropylene multi-tank sewage treatment package
Sewage treatment systems of pars Ethylene Kish produce in 4 sizes:
1. 2700 liter
2. 3750 liter
3. 4800 liter
4. 6500 liter
The highest size of sewage which can be treated with single-tank package is 2100 liter/24hour which treats with a tank with 6500 liter capacity. For treating higher volumes of tanks, number of tanks increase, for example, two-tank package that capacity of each tank is 4800 liter and can treat a sewage with 3300lit/day. The highest sewage volume which can be treated with propylene is 24m3/day24. This package includes 10 tanks with capacity 6500 liter.
All sewage treatment steps is done in single or multi-tank package similar to single-tank packages with this difference that baffle which divided single-tanks into two pools eliminated and one or several tanks change to initial pond and other tanks to aeration reactor.