a cost-effective modular recirculating filter for on-site wastewater systems.
There are five common causes of on-site wastewater treatment systems: hydraulic overload, excessive biome formation, poor design or installation, compaction and soilMineral bonding.
Solutions typically include pre-treatment of septic tanks
Discharge water tank wastewater by one of the following methods before discharge: aerobic treatment unit, attached-
Growth Media filters or artificial wetlands.
However, many consulting companies have-
Site wastewater treatment systems for individual residential or small commercial users.
Therefore, the author and his colleagues developed a modular, multi-layer, pre-
A pre-packaging circulating media filtering system designed (Patent being applied
Provide pre-treatment of septic tanks
Water tanks for residential and small commercial users.
The system is included in a single prefabricated concrete tank, includes a complete hypoxia recycling pool, a double-attached growth media filter, waste water for storage treatment, pumps, valves, closing pools for pipes, and a digital control system.
The device is designed to reduce biochemical oxygen requirements, total suspended solids, total nitrogen and pathogen levels in septic tanks
According to the approval of the regulatory authority, the water tank wastewater before final disposal is carried out through conventional Absorption Systems, underground drip irrigation or ground discharge.
Editor\'s note: long-through NEHA\'s-
Long term relationship with NSFInternational, NEHA was granted by NSF International to share a wide variety of papers with readers of the magazine
On 2000, at the NSF International Small drinking water and wastewater systems International Seminar and technology expo in Phoenix, Arizona.
This paper, \"cost
Effective module loop filter for On-
\"On-site wastewater system\" is one of them.
It is important to note that these documents have been screened by the NSFInternational Advisory Committee before they were submitted at the meeting, but they have not become peers
The NEHA reporter project reviewed the technical accuracy.
Because these papers contain useful and interesting ideas and information that may be delayed or lost if they are published through the journal\'s normal peer review process, NEHA has only minor edits.
We hope you look forward to more of these papers in future magazines!
According to 1995 reports from the US housing survey, about 25 million households in the United States use
Wastewater treatment system.
It is estimated that more than 2.
5 million of the systems failed or were not working properly. Jacquez et al. (1991)
A study estimate was cited that more than 1-
Half of the existing soil absorption systems in the United States do not work properly.
In the spring of 1997, Purdue University conducted a survey of the Indiana County Health Department to determine on-
On-site wastewater treatment, an estimated failure of 70% was found.
Surveys and studies in other states show that,
System failure rate of 45% to 70%. Failure of on-
A site wastewater treatment system can be defined as a surface treatment or discharge of untreated or partially treated wastewater.
Faults can also be defined as water discharge to wastewater rich in nitrogen, phosphorus or pathogenic microorganisms-
For example, such sewage is discharged in high-permeability soil areas with shallow, non-diving layers.
The on-site wastewater system is usually composed of sterile tanks, distribution boxes and soil absorption fields. Traditional on-
The field wastewater system uses soil to treat the sensestank effluent.
It is difficult to predict the actual treatment level of the traditional system, because it is impossible to continuously monitor the sewage in the drainage field.
The on-site wastewater treatment system failed due to various reasons.
National clearing house for small flows (NSFC)
Five common causes of system failure were identified: * hydraulic overload, * excessive biological community formation, * poor site assessment or poor system design or installation, * compaction and * soil-Mineral bonding.
When the amount of water flowing into the absorption system is greater than the amount of water that can move through the soil, a hydraulic overload occurs.
The ditches became saturated and the sewage was forced to discharge to the surface without proper treatment.
In extreme cases, wastewater can be returned to the septic tank and into the home.
Poor drainage of soil, high water use periods, improper design or construction, or leakage of septic tanks can all lead to hydraulic overload.
Septic tanks provide primary wastewater treatment by separating solids and floating materials from translucent wastewater.
Even if a filter is used, the resulting wastewater usually has a fairly high level of biochemical oxygen (BOD)
And suspended solids.
Bods and solids are discharged into the soil absorption field where they form an anaerobic layer or \"biological community\" within the ditch \".
This biological material may limit the flow into the soil, which forces the wastewater to return up or on the surface without proper treatment.
In traditional systems, the formation of biological at cannot be prevented, but proper and regular maintenance may slow the formation.
Many failures are attributed to poor design or installation
On-site wastewater treatment system.
This phenomenon is hard to understand because most states have designs, installations, and checks on-site systems.
For decades, the traditional systems have basically been the same design.
This common cause of system failure can be prevented.
Compaction fault of On-
Field systems are also common.
Compaction occurs when heavy objects compress the soil, thereby reducing the available void space.
This phenomenon prevents the flow of water over the soil and forces the waste water to return or surface without treatment.
Common reasons include the construction of improvement facilities, such as lanes and parking lots in the drainage area, and the use of heavy vehicles and equipment during construction to drive in the drainage area.
The cause of the system failure can also be avoided. Soil-
Mineral bonding occurs when natural soil ions are replaced by other ions that cause chemical changes in soil properties.
This change will occur in a certain amount of soil when water
The softener flushing water is discharged into the septic tank system. Soil-
Mineral bonding can lead to the formation of a non-permeable layer on the wall of the ditch, resulting in sewage surface or return.
The cause of this system failure can usually be prevented by separating the water
The softener is discharged from the septic tank.
Site system failures in the five common cause of system failures pointed out by NSFC can easily prevent three accidents by using good design and installation practices.
The other two, hydraulic overload and bio at formation, need a new way to open
Site wastewater treatment.
Several studies have shown that treatment of septic tanks
Storage tank emissions significantly reduced on-before soil treatment-sitesystems.
Converse and Taylor (1998)
The effects of high pre-treated sewage on the soil loading rate and the separation distance from groundwater and restricted layers were evaluated.
Site data for many septic tanks were collected, followed by advanced pre-treatment units.
These advanced pretreatment devices-
For example, sand filter, circulating sand filter, mud coal filter and good oxygen treatment device--
Decrease in total suspended solids (TSS)
And bacteria, allowing higher soil loading rate and lower separation distance than when septic tanks
Directly apply the water tank.
From many studies showing the positive effects of pretreatment, it is clear that the traditional on-
Can significantly reduce system failures on site-
Could be eliminated. -
Through the odor pretreatment system after using the septic tank.
The pretreatment system allows a higher rate of soil loading, thus preventing hydraulic overloading or reducing the size of the required absorption field.
In addition, by reducing cod and TSS in wastewater applied to the soil, the pretreatment system can eliminate or greatly limit the formation of biological communities in the absorption field.
Finally, since the soil is no longer the main treatment method, the pretreatment system reduces the separation distance required from the permeable surface to the groundwater or limited layer.
Converse and Tyler have recommended a separation distance of 12 to 24 inch, which is much less than the current code requirements in most states.
This advantage will allow on-
Site systems for marginal soil and high groundwater, which are common in many areas of the country with ideal construction sites.
The Apretreatment system will also allow on-
The site system in the high-penetration soil area, because the level of boards and pathogens in the odor will be reduced.
The most common pre-processing techniques can be divided into the following categories: 1.
Aerobic treatment unit (ATUs), 2. attached-
Growth media filter, 3.
ATUs is usually pre-
Ventilation provides an environmental engineering device for the growth of aerobic bacteria.
Aerobic bacteria can affect biochemical substances and TSS in septic tanks-
According to state regulations, the water tank effluent and system can be discharged to the soil absorption system or directly to the surface water.
Most ATUs usually use activated
Sludge Process with clarified or filtered components--or both--
Or they can use a fixed film treatment process.
The main advantage of the ATU is that it is a pre-
The designed pre-packaging system is capable of providing highly polished sewage in a limited space.
The main drawback is that ATUs is vulnerable to hydraulic shock, requires regular professional maintenance, requires the use of relatively complex equipment, such as a blower, requires regular pumping of excess or waste
Activated sludge to maintain a biological balance, and due to past failures, there may be some bad reputation in the regulatory community.
The attachment growth media filter is a biological and physical treatment system that uses a long history in wastewater treatment.
They include intermittent (single-pass)
Systems using a variety of media, including synthetic materials such as sand or gravel, peat and plastic, foam and textiles.
The filter system is usually composed of containers, downpipes, filter media, dispensing and dosing systems, and accessories.
Crites andTchobanoglous (1998)
Various mechanisms of the board of directors, TSS, turbidity, nitrogen, total coliform and fecal coliform in single bacteria, and viruses have been described
Pass and multi-pass systems.
Attached Growth medium filter is very effective for septic tank pretreatment
Tankeffluent is widely used for pretreatment-Site Wastewater.
The main advantages of attached growth media filters are their history of use, therapeutic effects, and overall simplicity.
The main drawback is the lack of pre-
Pre-packaged dfilter system designed (
Specific Design installation)
, Tends to insert certain types of media, as well as the need for professional maintenance of some systems on a regular basis.
The most common natural system for treating septic tanks
Artificial wetlands mainly use aquatic plants and bacteria to treat wastewater.
The main type is free water (FWS)
Underground flow (SF).
The FWS wetland is built in a basin or waterway full of shallow water and vegetation.
Wastewater is treated as it flows through vegetation through bacterial, physical and chemical processes.
The SF wetland is similar in shape, but usually smaller, filled with porous media such as rocks or gravel.
Plant Emergency vegetation in the medium and treat the wastewater when it flows out of date.
The water level of the AnSF wetland is usually designed to remain below the top of the medium.
Constructed wetlands have the advantages of simple maintenance and good ecological benefits.
The downside is very little, if any.
Engineering and pre-packaging systems are available (
Specific Design installation);
Performance depends on climate conditions;
Wastewater of consistent quality cannot be obtained;
Large areas of land are usually required;
Lack of consensus on design standards;
The physical, biological and chemical interactions that provide treatment are complex;
There may be pest problems;
Topography and soil may be limiting factors.
To prevent on-
On-site system, sufficient final disposal must be provided after septic tank treatmenttank effluent.
Typical methods of underground soil treatment include ditches or beds filled with gravel or other media, gravel-free ditches using Chamber systems, and underground drip irrigation systems.
These systems may be gravity. orpressure-dosed.
Surface oil treatment systems should be sufficient to disperse pre-treated septic tanks if properly designed and built
The choice of the \"best\" final disposition scheme will be determined by the requirements of the regulatory authority and the specific site features. A Cost-
Effective modular circulating media filter author and his colleagues have been engaged in consulting engineering for more than 10 years, specializing in wastewater collection and treatment in small rural communities.
Most of the company\'s projects include low
Pressure sewer system and batch reactor treatment facilities.
Financing of these projects includes grants and loans for rural development (
Household administration of farmers)of the U. S.
Ministry of Agriculture (USDA)
Loan funds, funds provided by the local ministry of commerce through the Ministry of Housing and Urban Development (HUD)
Combined with local financing.
Although relatively low
The company found it difficult to pay interest loans and a lot of grants
Low effective sewer
Even with the use of the latest innovative, centralized sewage treatment technologies, there are rural areas with density of faulty septic tank systems.
In response to this question
An in-house comprehensive study was carried out to evaluate other technologies of concentration and dispersion, providing solutions for failed septic tank systems.
On the basis of this study, it is a cost to determine the circulating media filter-
For many parts of the country, an effective solution for a failed septic system.
Circulating media filter is a mature technology that is very effective for the treatment of septic tanks
Water tank out of the water, simple operation and maintenance.
They can be used to fix the faulty system.
The filter is buried and relatively unobtrusive, a major concern for residential users.
The loop filter is much smaller than a single filter
Through the filter, thereby reducing the required area, and it usually performs better than a single filterpass filter.
The study also determined that the main obstacle to the large-scale use of recycled media was the need to design and build separately for each site, and that once installed, no entity was responsible for the operation and maintenance of the system.
Many consulting engineering companies are not interested in design
Site wastewater treatment systems for individual residential or small commercial users.
Without proper design, the systems would force the installers to design and build a somewhat complex mechanical handling system.
In areas where some installers are not familiar with the technical circulating media filtration system built for each site, this situation has proved to be a problem, including sterile tanks;
Recycling pool with pump, controller and recycling valve;
The media filter of the feeding system and the down well;
And a pot of Medicine (if required)
Final treatment of treated wastewater using pumps and controllers.
Many installers do not want to provide operation and maintenance services to the system once they are installed, and the responsibility always falls on the system owner.
Few owners have enough experience to operate and maintain the site
Built-in circulation media filtering system.
The author and his colleagues began to seek solutions to these problems and developed a modular pre-packaging
Circulating media filters designed for residential and small commercial users.
All the components are assembled in the workshop, greatly reducing the requirements for on-site installation.
On-site installation involves excavation and placement of conventional septic tanks with odor filters for preliminary treatment and then excavation of module filters.
After the excavation is completed, place the prefabricated unit with the large boom truck and connect the entrance sewer.
The installation of the discharge pipe depends on the type of final disposal selected.
The authors usually use underground irrigation.
The power supply line extends from the home or building to the unit and is connected to the digital control panel in the unit.
Telephone lines can also be provided for remote alarm monitoring and control via a modem card in a digital controller.
This modular pre-
Designed, prefabricated recycled mediafilter solves many problems and shortcomings related to septic tank pretreatment
Designed to solve on-
Site system failure.
The circulating media filtering technology has been well proved and has a valid history.
All the design works of the system have been completed and the modular filter will work under the specified flow and load.
Modular filters are designed to be unaffected by the typical flow in residential and small commercial applications, reducing the typical on-
On-site systems, especially the underground drip irrigation method, are the preferred method for handling odor.
Site construction involves only the installation of components, thus reducing the possibility of problems with experienced installers.
Simple system operation and maintenance;
Only two small submersible pumps can be moved.
Because the unit was completely buried, it was rather unobtrusive for homeowners, except for the entrance cover and plumbing.
The system is quiet and has no peculiar smell.
The modular filter contains a digital control system that controls treatment operations, monitors the health of the system, and alerts if there is a problem.
In addition, the unit saves costs compared to the typical sitebuiltsystems.
On-site installation time and equipment requirements are less than on-site --
Built-in cycle and single
By filtering the system.
The type of final disposal option selected will also affect the cost of the system.
Based on the author\'s experience in Indiana, website-
Circulating filtration systems using an underground drip irrigation system for final sewage treatment, including design and construction, the final sewage treatment cost for the entire project is about $20 per gallon.
For a typical four
Bedroom homes use 600 gallons per day, so the total installation cost is about $12,000.
It is expected that the total installation cost of the modular system will be approximately $8,000 to $10,000 for the same design process.
In contrast, the average cost is 600-gallon-per-
The day routine system in Indiana is $4,000 to $5,000, a600-gallon-per-
The price of rising sand dunes is between $10,000 and $.
The average flow rate of the basic modular filter designed and manufactured by the basic system design author and his colleagues is 600 gallons per day, which corresponds to a typical four-
A bedroom home in Indiana that requires 150 gallons of design flow per bedroom per day.
The modular filter is designed to be installed in a prefabricated concrete tank, which is about 12 feetlong wide, about 6 feet deep and about 7 feet deep.
The filtered wastewater from the sensory pool enters the unit in the hypoxia recycling pool at the bottom of the prefabricated concrete pool, providing a carbon source for anti-gasification.
The recycling pool is designed to store more than 600 gallons or flow throughout the day.
This storage capacity, as a balanced pool, can inhibit the daily traffic and surge traffic typically experienced in residential and small commercial applications.
Waste water in the recycling pool is time-
Install a single compression pump on two-layer filter media.
In the controller, the timing sequence can be easily changed to provide a filter for the selected media at the appropriate rate.
Two layers of filter media are used to reduce the overall size of the unit, allowing the construction, transportation and installation of traditional equipment.
The loading rate of the designed filter is 5 gallons per square foot per day, resulting in a bed area of more than 120 square feet.
Each filter is injected by the same submersible pump through the pipe network, which uses the orifice plate hydraulic to balance the flow to each filter.
The drain at the bottom of each filter collects the filter fluid and returns the flow back to the recycling pool.
The unit is designed to provide a recycling ratio of up to 4 to 1, thus passing the filter up to five times before discharge.
The recycling ratio can be changed by the control device and the recycling valve.
The air sprayed with waste water onto the filter through the vent duct and maintains good oxygen, the device through biological, physical, and chemical processes.
The aerobic filter has also been designed to convert ammonia into nitrate through the process of nitrate.
The filtration liquid is guided through the recycling valve installed in the pump chamber of the recycling pool.
The water level in the circulation pool controls the recycling valve through a floating device.
When the water level in the recycling pool is low, all filtration fluids are returned to the recycling pool.
When the level rises, a ball floats and blocks the valve, and the filter is separated proportionally between the recycling pool and the final effluent dosing pool according to the selected recycling ratio.
The circulation valve always keeps the lowest water level in the basin.
The presence of water allows the filter to be shut down continuously during low or no flow periods (such as evenings, holidays or seasonal absence periods.
The modular filter also contains a complete dosing pool for storing treated wastewater before final disposal.
The dosing base may contain the time of the submersible pump-or level-
Add the final sewage to the absorption field, drip irrigation system or other treatment methods.
If the gravity flow is available and permitted by local regulations, an dosing pump may not be required.
Both the dosing pump and the recycling pump can be time-dosed.
If a high level of wastewater is encountered, they also have a covering device to start the pump.
The digital control system monitors the pump and alerts various pump failures.
The pilot test results author and his colleagues are currently evaluating several media for modular loop filters.
The first media for testing is peat, which is selected because of its successful use on many single media
Through the filter, its ability to significantly reduce the level of pathogens and its ability to reduce total nitrogen.
The weight of clay coal is also very light, which is advantageous in the early commercial development
In April 1999, a small waste water treatment plant in Samman, Indiana, installed a test device.
The pilot plant is designed with an average flow rate of 600 gallons per day, and the original domestic wastewater from the inlet structure of the treatment plant is regularly pumped to a1, 250-
Gallon prefabricated concrete septic tank.
The septic tank includes an outlet filter with an alarm. The septic-
The water outlet of the water tank flows into the pilot filtration device through a well.
The discharge of the pilot filter is returned to the water inlet structure of the waste water treatment plant through the flowmeter pump.
Portable, refrigerated, automatic composite sampler mounted on the water inlet structure of rawwastewater, in septic tank-
Sampling Wells, circulation pools and dosing pools for tank effluent.
The staff of the processing plant initially conducted laboratory tests when the system was started.
After start-up, the outlet quality of the filter measured with cod and TSS is very good.
Additional laboratory tests have been completed in both certified laboratories.
The data is shown in Table 1.
At startup, there was no mechanical problem with the device and no problem since.
However, there has been a situation of mud-coal blockage, which is caused by the high hydraulic load of the circulating filter.
During the test, the recycling ratio has changed, and at a lower recycling ratio, the filter does not seem to be easily blocked.
By bods and TSS measurements, the quality of the effluent has nothing to do with the recycling ratio.
However, the reduction in ammonia and total nitrate was disappointing. Brook (1988)
It is pointed out that the concentration of organic nitrogen in wastewater is single
Up to now, 90 to 95% and 95 to 99% respectively have been reduced by peat filters, and the pilot results of circulating peat filters in this study have not been shown to be effective.
The reduction of pathogens in circulating peat filters is also disappointing.
The laboratory results of the fecal coliform bacteria were inconsistent and did not support Brooks\'s results showing that the feces were almost completely reduced.
The author and his colleagues are now testing other types of media.
A combination of sand washing and gravel is currently being used.
See Table 2 for data on effluent quality.
The author and his colleagues are also evaluating the use of iron.
As part of the sand/gravel medium, the rich sand can remove phosphorus and further reduce the nutrient load of the oil.
National On-site Demonstration Project (NODP)
Has been directing in benzze County, Michigan.
The project solved the problem of phosphate load on the surface and groundwater.
NODP is funded by the US government. S.
EPA, coordinated by the National Natural Science Foundation, assists small communities in funding, installing, monitoring and managing models
Site system as cost
An effective and feasible alternative to the central sewer system.
Several types of synthetic media will also be tested in the future to determine the commercial modular pre-
Pre-packaged media filter designed.
Work to date has shown that this system can be easily manufactured and installed with limited demand for engineering design, construction equipment and experience-
And the cost is reasonable.
The test shows that the system can provide a high degree of pretreatment without mechanical failure, and the operation and maintenance are simple.
Correspondent: Kevin R. Chaffee P. E.
President of Earth environmental systems, 204 South St.
Bartsville, at 47006. (
International Symposium and technical Expo record for small drinking water and wastewater systems, approved by the NSF, January 12--
2000 Phoenix, Arizona)REFERENCES [*]J. L. Brooks. 1988.
The role of fungi in the wastewater treatment system of water Moss.
University of MaineJ. Converse, E. J. Tyler. 1998.
Soil diffusion with high pretreatment-
Precautions included in the code.
1998 NOWRA minutes, Page 42-49. R. Crites, G. Tchobanoglous. 1998.
A small and decentralized wastewater management system. McGraw-
Hill series of water resources and environmental engineering. N. Eddy.
Septic tanks in the United StatesS--
How many people, where are they, are they working properly?
Small flow, Spring 1999; Vol. 13,No. 2.
National Small Traffic Information Center, University of West Virginia. Jacquez, R. B. , F Vora, N. Kareem, X. Wang. 1991.
On-site treatment of septic tanks
The tank outlet of the rotating biological contactor.
On-site wastewater treatment, Volume 6, minutes of the Sixth National Symposium on sewage systems for individuals and small communities. ASAE. Michigan. A. Jantrania.
On-site wastewater management system in 21st century.
Small flow, Spring 1999; Vol. 13, No. 2.
National Small Flower Exchange, University of West Virginia. NFSC Hotline--Q & A.
Small flow, Spring 1999; Vol. 13, No. 2.
National Small Traffic Information Center, University of West Virginia. Research.
The flow is small, down 1999; Vol. 13, No. 4.
National Small Traffic Information Center, University of West Virginia. C. Taylor, J. Yahner D. Jones. 1997.
Evaluation of On-
Sitetechnoology in Indiana: A Report to the Department of Health in Indiana.
Agronomies and agricultural bioengineering.
Purdue University. Indiana. (*)
Editor\'s note: since this paper was originally published at the NSF Conference at the International Symposium and Technology Expo on small drinking water and wastewater systems, the references do not conform to the normal Journal of Environmental Health style.
* About 25 million families in the United States
Site system for wastewater treatment.
* Estimated more than 2.
5 million of the systems failed or were not working properly.
* Fault of traditional on-
Common reasons for on-site wastewater treatment system: 1.
Hydraulic overload, 2.
Excessive biological formation, 3.
Poor design or installation, 4.
Compaction, 5. soil-Mineral bonding.
* Solutions usually include the treatment of wastewater by one of the following methods: aerobic treatment unit, attached-
Constructed or constructed wetlands.
* However, many consulting companies are not interested in design
Site wastewater treatment systems for individual residential or small commercial users.
* As a result, the author and his colleagues have developed
Circulating media filters designed for residential and small commercial users.
* All components are shop-assembled.
* Site construction only involves the installation of components.
* Only two small submersible pumps are moving parts.
* The author and his colleagues are evaluating several media types used in the filter.
* With peat, measured by biochemical oxygen requirements and total suspended solids, the quality of the effluent is high.
However, the reduction in ammonia, total nitrate and pathogens was disappointing.
* Washing sand and gravel are also being tested.
* The author and his colleagues are evaluating the use of iron
To provide the removal of phosphorus and further reduce the nutrient load of the soil.
* At the same time, the pilot test shows that the system will provide a high degree of pre-treatment, no mechanical problems will occur, and the operation and maintenance will be simple.