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1.1: Basic Overview/Introduction To Wastewater Treatment

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    Learning Outcomes

    • Understand the importance of proper wastewater treatment
    • Describe and construct the urban water cycle
    • Analyze wastewater origins and how it is conveyed
    • Differentiate between residential and industrial/commercial wastewater
    • Evaluate the typical job function of a wastewater treatment operator
    • Explain the certified wastewater treatment operator licensing requirements


    Proper wastewater treatment and disposal is essential for the vitality of a functioning society. Without it, a community’s environment can be severely polluted and the health of the public is at great risk. To better understand the relationship between wastewater treatment and water treatment and distribution, examine the urban water cycle. Like the typical hydrologic cycle, which shows the natural movement of water in the environment, the urban water cycle shows how water is moved in an urban environment.

    In some cases, wastewater that has been treated by a wastewater treatment plant will be discharged back into a natural water body. Water from that water body will then be used by downstream communities as source water for their water treatment plants. If either of these two treatment facilities are not operating to current regulations and standards, public health is at risk. In addition, if the wastewater treatment facility is not operating properly there can also be additional environmental damage to the water body.

    Currently, there is a paradigm shift in water treatment and the line between water, wastewater, and stormwater is becoming thinner and thinner. For example, the use of reclaimed water from wastewater treatment plants can be used for various beneficial uses instead of being discharged into a water body. The term “One Water” is being used more frequently to encompass the idea that all of these water sources are beneficial and more innovation is needed to use these sources more efficiently. However, the focus of this textbook will be on the inner workings of a conventional wastewater treatment plant. The goal is to give you the vocabulary and knowledge needed to understand how wastewater treatment operators can take a contaminated water source and treat it to a level of quality that will not endanger the environment or public health.

    The term wastewater has become the common term to describe sewage. In fact, when we talk about conventional wastewater treatment plants we are talking about facilities that take the used water from residences and businesses of a community and clean it up. Wastewater is anything and everything that goes down the drains of these households and businesses. All the water from sinks, garbage disposals, toilets, dishwashers, bathroom drains, and washing machines are considered residential wastewater. There is also commercial or industrial wastewater. Many manufacturing processes that use water, typically for washing or cooling purposes, need to properly dispose of this water. In some cases, this wastewater may be treated onsite before it is discharged into the wastewater collection system. Some municipalities will require the manufacturer to obtain an industrial waste permit that regulates what they are allowed to discharge.

    Wastewater Treatment Plant Operators

    A wastewater treatment plant operator’s main responsibility is to ensure the wastewater treatment facility is being operated and maintained so the wastewater leaving the facility meets the limits of their National Pollutant Discharge Elimination System (NPDES) permit. We will learn the specifics of exactly what an NPDES is in later chapters. Throughout the rest of this book, we will look at the main roles and functions that wastewater treatment plant operators do every day.

    Licensing Requirements

    The State Water Resources Control Board (SWRCB) is the regulatory authority in California for many aspects of water laws and regulations. They are also responsible for overseeing the Operator Certification Program. In California, it is mandatory to be certified by the SWRCB if you are employed in the operation of a water distribution system, water treatment facility, or wastewater treatment plant.

    To become certified there are three things that must be accomplished by the individual seeking certification. First, is to obtain the required amount of education for the level of certification. Each vocation has five levels of certification, with grade five being the highest. As the level of certification increases, more education is needed. The second requirement is experience. Just like education, higher certifications require more experience. However, these two requirements work together. The more education one has, the less amount of experience needed. Likewise, if one doesn’t have a significant amount of education, they can still obtain higher certifications by gaining more work experience. The education and experience requirements for the Wastewater Treatment Operator certifications can be found here. The final thing is to pass the certification exams which are offered twice a year, in the spring and fall.

    Becoming certified as a Wastewater Treatment Operator Grade 1 requires that the applicant has gained one year of work experience. This one year of work experience is one of the hardest hurdles for many people to overcome. Many employers want to hire people that already have certifications, but you can’t get certified if you don’t have experience. Many wastewater treatment facilities understand this predicament and offer what is called an Operator-In-Training (OIT) position. To obtain a Grade 1 OIT certificate you must have a high school diploma or GED, have six educational points by taking a college-level math or science course, and be employed by a wastewater treatment facility. These positions are becoming more competitive and often employers require additional related work experience or additional education. Successfully passing the certification examination can help set you apart from other applicants.

    Type of Work

    The type of work a wastewater treatment operator is involved in will be varied and depends on a lot of different factors. A common job description will include something along the lines of “to ensure the operation of the treatment facility and ancillary equipment in order to meet effluent requirements”. The effluent of a wastewater treatment plant is the water that leaves the facility once it has been treated. To ensure the effluent requirements are met, an operator's typical job will include monitoring and logging critical information such as pump pressures and flow rates, tank levels, and water quality parameters such as turbidity and chlorine residual. There is also preventative maintenance that is required. Some tasks could include taking portions of the treatment system offline for cleaning and/or repairs.

    Throughout the treatment system water samples will need to be taken and tested for various constituents, either for regulatory compliance or process control. Depending on the facility, the sampling may be done by operators or by laboratory technicians. However, it will almost always be the certified operators that will review the laboratory results and determine if any adjustments to the treatment process are needed.

    It’s important to note that wastewater treatment plants are industrial facilities and some of the work can be very dangerous. Operators can be working with heavy machinery such as forklifts, large pumps, and cranes. There is also high voltage electrical equipment that the operator will interact with on a daily basis. There can be situations where there are high-pressure lines and even the possibility to be exposed to harmful chemicals. This book will have a whole section dedicated to covering these safety topics and more.


    There are many different types of work available in the wastewater treatment industry as a whole. While this textbook will focus on the specifics of the job duties of a wastewater treatment operator (WTO), there are many other supporting jobs in both the public and private sectors. Most of the WTO positions are available through the public sector. For example, a city will be the owner and operator of a municipal wastewater treatment facility. That city will then employ as many WTOs as necessary to operate the plant. However, there will be many other jobs required to keep the facility running aside from the operators. Depending on the size of the plant, there can also be workers skilled in the maintenance of pumps and machinery, electricians, and instrumentation technicians. These jobs can also have their own trade certifications that may be required by the employer. In addition, there may be laboratory staff, administration personnel, engineers, managers, and financial experts. All of these positions will work together to keep the plant running. But it’s important to remember that at the end of the day, it’s the certified Wastewater Treatment Operators that can be legally responsible for the quality of water leaving the facility and compliance with the NPDES permit.

    There are also many job opportunities in the private sector. There are many “package plants” that smaller private industries will operate to treat residual waste from a large scale manufacturing process. A brewery, for example, may need to treat their brewing process wastewater before the water can be disposed of in the municipal sewer system. As of 2013, these privately run wastewater treatment plants require workers that are involved in the operation of the plant to meet the same licensing requirements as publicly operated wastewater treatment plants.

    This page titled 1.1: Basic Overview/Introduction To Wastewater Treatment is shared under a CC BY license and was authored, remixed, and/or curated by Nick Steffen (ZTC Textbooks) .

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