Full Answer
What is infiltration and inflow in sewage treatment?
By transporting the sewage from our homes and other facilities to the wastewater treatment plants, the sewer systems protect public health, properties, and the environment. However, in addition to the sanitary sewage, there is an infiltration and inflow (I/I) of other water to the sewer system.
What are the risks of wastewater infiltration?
In addition to the potential health risks associated with infiltration, the additional water within the lines makes it more difficult for wastewater treatment plants to properly treat the volume that comes through the plant. As a result, poorly or untreated waste is ejected into the environment.
How do main maintenance workers distinguish between inflow and infiltration?
Maintenance workers distinguish inflow and infiltration from sewage by calling infiltrated water “clear water,” even if the water is dirty. The clear water distinction is merely a way of stating it does not have sewage in it. How Do Inflow and Infiltration Affect Sewage Systems?
Why do wastewater treatment plants suffer capacity loss?
Many wastewater plants suffer capacity loss due to inflow and infiltration. For the majority of municipal treatment plants there is likely to be a seasonal impact resulting from rain events, snowmelt, spring thaw, etc.
What is the difference between infiltration and inflow?
Infiltration occurs when groundwater seeps into sewer pipes through cracks, leaky pipe joints and/or deteriorated manholes. Inflow is stormwater that enters the sewer system through rain leaders, basement sump pumps or foundation drains illegally connected to the sewer.
Why flow rate is important in wastewater treatment?
Flow measurement is a basic and important control parameter for ensuring that clean, high-quality water is available. Applications ranging from water storage and transmission to wastewater treatment, leak detection and pump management cannot be done without flow meter technology.
How is inflow and infiltration measured?
Estimating Infiltration and Inflow (I&I) Average annual I&I rate can be estimated by subtracting the BSF rate from average annual flow rate. Annual I&I volume can be estimated by multiplying the average annual I&I rate by 365 days.
What is infiltration flow?
Infiltration and inflow (I/I) is excess water that flows into sewer pipes from groundwater and stormwater. Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections.
What is flow rate in wastewater treatment?
The average sewage flow rate is usually about the same as the average water use in the community. In a lateral sewer, short-term peak flow rates can be roughly four times the average flow rate. In a trunk sewer, peak flow rates may be two-and-a-half times the average.
What is the importance of flow equalization?
Flow equalization is the process of controlling hydraulic velocity, or flow rate, through a wastewater treatment system. The equalization of flow prevents short term, high volumes of incoming flow, called surges, from forcing solids and organic material out of the treatment process.
In what way does inflow and infiltration affect the design estimates of sanitary sewer systems?
Infiltration and inflow to the sewer system may exhibit negative effects on the WWTP such as dilution of pollutant concentration in the wastewater resulting in increased pollutant load to the recipient water, reduction of sewer system and wastewater treatment capacity resulting in hydraulic overload of up to 100% and ...
How do you calculate infiltration?
Compute infiltration rate (I) by dividing water depth (H) by elapsed time (t). I = H/t 5.
How do you calculate peak hourly flow in wastewater?
Peak hourly flow for each contributing area calculated at an average flow multiplied by a peaking factor: C Peak Factor = 1 + 14 (Harmon Formula)4+P1/2Where P = the population in thousands.
Why is inflow and infiltration a problem?
Inflow and infiltration reduce the ability of sanitary sewer systems and treatment facilities to transport and treat domestic and industrial wastewater. As a result, wastewater treatment processes can be disrupted and may allow poorly treated wastewater to be discharged to the environment.
What is the difference between drainage and infiltration?
Infiltration Number is another name for Drainage Texture; both are same, as the equations indicate. However, as a proof of this, you can refer the the report of Indo-British Ground Water Project (1984) on Ground Water Resources of the Upper Betwa River Basin, India published by Central Ground Water Board (CGWB), Govt.
What is an inflow pipe?
An inflow pipe brings in stormwater from various sources into the sanitary sewer system at points of direct connection to the system or discharge into sinks directly connected to the sewer system.
What Are Inflow and Infiltration?
Both inflow and infiltration are the addition of waste or groundwater into a sewage system. While both contribute to the problem, these issues have slightly different means of entry from each other.
What happens when a sewer overflows?
It fills the sewer. Once at capacity, the sewer overflows – flooding basements, streets and sidewalks. Communities downstream from the overflowing sewer system are often most affected. Due to their location, they must accommodate not only the flow from their sewage system but also the overflow from all communities upstream.
Why is it important to inspect sewer lines?
Without proper inspection and maintenance, ground and stormwater can invade the sewer system, causing potential overflow and hazardous health conditions. That is why it is so important to regularly inspect pipes and perform maintenance, as well as repairing any damage when it is discovered.
How many homes can a sewage system handle?
With proper maintenance, these systems can handle as many as 200 homes on a single 8-inch sewage pipe. However, sewer lines can become compromised due to inflow and infiltration in the system. (To learn more about sewer systems, check out The Complex World of Sewer Networks .)
Why is overflow costly?
Overflow due to infiltration and inflow is costly. Cities must pay to correct the problems. There are also costs associated with cleanup and potential lawsuits from affected homeowners. There may also be fines related to damage caused by overflow if the issue is not corrected.
How to find cracks in sewage lines?
One of the best ways to find cracks in sewage systems is through a pipe inspection using closed-circuit television, or CCTV. Using a small camera to travel through the pipes, workers can see the interior of the lines on a CCTV while remaining topside. The camera rotates 360° to give a full view of the inside of the pipe.
What is dye testing in sewage?
Along with smoke testing, some areas use dye testing, often as a way to confirm smoke testing. With dye testing, workers pump water with a nontoxic dye into the stormwater system.
What is inflow and infiltration?
Inflow and infiltration is defined as groundwater and stormwater that enter a sewer system. Collection systems can be damaged when they are forced to transport more flow than they are designed to handle. Increased effluent also raises costs for wastewater treatment facilities, because harmless stormwater and groundwater mix with sewage. In many cases, inflow and infiltration (I&I) accounts for up to 45% of the annual flow to treatment plants.
What is the difference between inflow and infiltration?
Infiltration occurs when groundwater seeps into sewer pipes through cracks, leaky pipe joints and/or deteriorated manholes.
What are the financial implications of excessive I&I?
The financial impact of inflow and infiltration includes both treatment costs and regulatory penalties.
What is I&I’s impact on water treatment capacity?
Inflow and infiltration robs valuable capacity from treatment plants. Such capacity shortfalls can lead to damaging and costly sanitary sewer overflows (SSOs). Thirty-five percent of water entering a water treatment plant is I&I, according to the Chalmers University of Technology’s Division of Water Environment Technology. Another 35% is stormwater, and the remaining 30% is sewage. In other words, 70% of total flow into a treatment facility is water that would not need treatment had it not entered a sewer line.
What is exfiltration in water?
Exfiltration is defined as the leakage of wastewater out of a sanitary sewer system. Exfiltration seeps out of broken or damaged pipes and manholes. Wastewater that leaks from defective pipe joints and cracks may contaminate ground and surface water and nearby water bodies.
How does groundwater seep into sewer pipes?
Groundwater seeps into sewer pipes through cracks, leaky pipe joints and deteriorated pipes. A CCTV inspection is the most thorough way to find and understand I&I in pipelines. Sewer inspection crawlers use a video camera mounted on a remote-controlled robotic crawler that is connected to a monitor. An operator watching the video can stop to study parts of the pipe to find the specific location and cause of infiltration.
What happens if you exceed the capacity of a wastewater collection system?
Exceeding the capacity of the collection system can result in discharge of untreated wastewater into the environment. This discharge may come from collection system components or from a treatment system that doesn’t have the capacity to treat the water. Infiltration can also cause pipe structure failures due to erosion of soil support, and ground subsidence due to erosion of underground soil.
Abstract
Inflow and infiltration is a phenomenon in sewerage systems that give negative effects on the environment and human health if not addressed properly. Collaboration has been made between Universiti Malaysia Pahang and Indah Water Konsortium Sdn.
Notes
This study was financially supported by the Malaysian Ministry of Education in the form of RACE research grant RDU 141302. The authors gratefully acknowledge the support given by the staff of Indah Water Konsortium Sdn. Bhd. The authors also want to thank lab assistants who assisted in the data collection.
What is infiltration in sewer system?
Infiltration is a physical factor (USEPA, 1970) which happens unintentionally because of damages in the wastewater sewer system (Sola et al., 2018). The infiltration typically takes place at defective joints, pipes, connections, and manholes (USEPA, 1970). Defects in the pipe system can be caused by, e.g. overloading, hydrogen sulphide attacks, and root intrusion (Malm and Svensson, 2011). If the system is damaged and the groundwater table located higher than the defected pipe, infiltration will take place (Fenner, 1990). Hence, infiltration is dependent on the status of the sewer system, the hydrogeologic conditions, and possible sources of infiltration water.
What is the abbreviation for infiltration and inflow?
In this review the term infiltration and inflow with the abbreviation I/I is used to describe both the concept of water entering the wastewater sewer system as well as the water itself. These terms are commonly used in the reviewed literature. However, many alternative terms are also used for describing I/I and these are presented in Table 1.
What is cost benefit analysis?
(2009) describe cost-benefit analysis (CBA) as “a technique for measuring whether the benefits of a particular action are larger than the costs, judged from the viewpoint of society as a whole”. The CBA has been used for a very long time and can have many different applications (Johansson and Kriström, 2018). CBAs can be applied on projects with the aim to improve the environment and are in these cases called environmental CBAs (WHO, 2003). Figure 10 displays the basic steps of a CBA.
What is digital water?
The term Digital Water refers to the digitalisation of the whole water system and the use of data in the water context can also be called Smart Water, Internet of Water or Water
What is the effect of I/I on wastewater?
I/I results in more water in the wastewater sewer system and to the WWTP (e.g. Bäckman, 1985; USEPA, 1970; Dirckx et al., 2016; Kaczor et al., 2017; Sola et al., 2018). The additional volumes of water lead to a larger energy consumption in terms of pumping as well as a larger need for maintenance and a reduced life span for the components (USEPA, 1970). More water in the WWTP also results in a higher use of chemicals for the treatment processes (Bäckman, 1985). On the other hand, a decrease of I/I would lead to a higher concentration of sanitary sewage which significantly would increase the chemical cost for sulphide mitigation per unit (Sun et al., 2015). However, the total treatment cost would still decrease because of the decreased flows.
What causes inflow in storm sewers?
Inflow is caused by intentional or unknown connections of stormwater to the wastewater sewer system or by surface water (USEPA, 1970), see Figure 4. The rainfall induced inflow can either be categorised as direct or indirect depending on the response time.
How does a sewer system affect the environment?
However, in addition to the sanitary sewage, there is an infiltration and inflow (I/I) of other water to the sewer system. This additional load can result in adverse effects such as basement flooding, combined sewer overflows, and larger pumping and treatment costs. I/I can originate from rainfall but also from sources such as groundwater, surface water or leaking drinking water pipes. Expected climate change effects include more intense rain events and periods of higher water levels which will increase the problem of I/I. Hence, it is important to manage I/I in a proper way by implementing efficient measures that provide the largest societal gain from a sustainability point of view.