Wastewater Systems

Wastewater Systems 4100 Idela Ave. McAllen, Tx. 78503 Phone: (956)681-1750 Fax: (956)681-1767 Web: https://mcallenpublicutility.com/departments/wastewater-systems/

Table of Contents

Welcome ...... 1

Biological Nutrient Removal (BNR) ...... 2 Reclaimed Water

Extended Aeration ...... 3 Reclaimed water, which can also be called reuse water or recycle water, is converting wastewater into water that can be reused for Wastewater Collection ...... 4 landscaping, industry, fire protection, construction (soil compaction and Reclaimed Water ...... 5 dust control), etc., but where reclaimed water’s true benefit arises for a city is conserving water. With the Rio Grande Valley prone to droughts;

McAllen Public Utility (MPU) has always been a leader in the conservation of water and is the first Valley city to create a residential reclaimed water irrigation program to conserve potable water. MPU is the first city south of San Antonio to provided reclaimed water to a residential subdivision to irrigate their lawns; furthermore, MPU is already saving over 1.0 billion gallons of water per year distributing reclaim water too Calpine energy. Calpine energy uses reclaimed water for their electrical plant in their cooling towers.

There are two types of reclaimed water: Type I and Type II. Type I is superior than Type II, and Type I is used for the above mentioned. Reclaimed water is regulated by Texas Commission of Environmental Quality (TCEQ) and our WWTPs must meet strict regulations to produce this water.

Many other cities use reclaimed water such as: San Antonio uses reclaimed water to augment stream flow in the San Antonio River along the famous River Walk. The cities of Amarillo, Lakeway, Las Colinas, Lubbock, and Odessa use reclaimed water to irrigate golf courses and landscapes. All these cities along with McAllen have seen the importance of conserving water in their cities.

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Wastewater Collection System Welcome……..

Wastewater collection system (WWCS) is a vital First and foremost, I would like to Welcome you to one of our Wastewater (WW) Treatment part of the entire Wastewater Systems. It is the Plant (WWTP) facilities. I truly believe by the time you leave the facility you will have learned veins and valves that transports wastewater (ww) something new about where water & waste goes when you flush the toilet, turn on the shower, to wastewater treatment plant. WWCS consists: wash dishes, etc., and what happens to it. lift stations, force mains, gravity ww mains (pipes) McAllen Public Utility (MPU) Wastewater Systems has two Aerobic WWTPs, one on the North and manholes. side and one on the South side of McAllen. Aerobic means the wastewater needs oxygen. The WWTPs are known as Extended Aeration Plant and Biological Nutrient Removal Plant. A Lift Station is a pumping station that pumps the You will find a brief description of how the plants work in the brochure. These two plants treat wastewater through a force main to either a over 12 million gallons per day (MGD) of wastewater, but it is important to know why this manhole or another Lift Station. Lift stations are wastewater should be treated. In a nutshell, to protect public health and protect the installed due to flat terrain because there is not environment. Without WWTP we would have diseases spread across our country. If you enough slope to install a gravity ww main, so the look at history, WWTP is one of the most important invention to our society along with the wastewater cannot flow naturally to the WWTP. addition of adding chlorine to our water and wastewater system to stop the spread of The Rio Grande Valley is flat terrain. waterborne illness.

A manhole is an inceptor for wastewater and is MPU WWTPs are environmentally friendly. Both plants produce a sludge that can be used installed in the WWCS if the angle changes or for fertilizer and produce reclaimed water for irrigation purposes. The NWWTP is the first there are two different pipe sizes attached to the WWTP south of San Antonio to use reclaimed water to irrigate residential homes at a manhole or elevation changes. Manholes are made of concrete or fiberglass are subdivision-Tres Lagos. This will save millions of gallons a year of potable water. 30” wide and can be from 3 feet to 30 feet deep. Manholes has cylinder shape. Let me say something about the professional operator (s) that operate these WWTPs. All Operators that work at a WWTP must be license by Texas Commission on Environmental Wastewater collection systems is vital part of our Quality (TCEQ), who regulates water and wastewater facilities in Texas. They must take and everyday living to protect public health and the pass a state exam and if they fail the exam, they cannot work at the WWTP. There are four environment. (4) licenses they can achieve starting with the lowest TCEQ Wastewater license which is the Where does wastewater come from? D, then C, B, and the highest license that can achieve is the A. To get the TCEQ WW “A” license you need over 120 hours of educational classes and 5 years of “hands on” Wastewater comes from toilets, bathtubs, experiences, if you have a college degree; if you do not have a college degree, you need kitchen sinks, bathroom sinks, washing eight (8) years “hands on” experiences. MPU require a TCEQ WW “C” license or higher to machines, etc; also, there is industrial waste that come from food processors, work at the WWTPs. refineries, dairies, paper mills, slaughter houses, metal plating factories, etc. All From the beginning how the wastewater comes in, known as influent to how it’s treated and these types of business produce a wastewater that is sent via our wastewater discharge from the WWTP known as effluent. WWTP is a facility you will never forget. I hope collection systems to our WWTPs. Wastewater is 99.9% water and 0.1% solid. you leave knowing wastewater treated and produced is reclaimed to save millions of gallons One important note to always remember; only two things should be flushed down of potable water yearly. Most of all that dedicated licensed professionals are operating these a toilet: human waste and toilet paper, anything else such as flushable wipes, WWTPs and that we are here to protect public health and protect our environment. Thank diaper, plastics, Q-tips, etc. will clog the wastewater collections causing sanitary you for visiting McAllen Public Utility’s Wastewater Treatment Plants. sewer overflow. Sincerely,

David Garza

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Biological Nutrient Removal (BNR) South Wastewater Treatment Plant Anaerobic is without oxygen and bacteria will die causing the solids to become septic. The solids will be sent to the belt presses or drying beds where it will be dewatered South Wastewater Treatment Plant (WWTP) is a 10 million gallon per day (MGD) biological more and eventually dry and turn into sludge. The sludge will be transported to a farm process in the treatment of wastewater (sewage) known as Biological Nutrient Removal where it will be used for fertilizers. This is just a snap shot of what a South Wastewater (BNR). The process adds dissolved oxygen like the extended aeration process, but the Treatment Plant does, there so much more in the biological process, chemical difference is that the BNR has two zones. First zone is known as Anoxic. Anoxic uses less process, electrical and mechanical process that happens in Wastewater Treatment than 1 mg/l of dissolved oxygen (DO). In the process anoxic zone creates denitrification. Plant, but know our main goal is always to protect public health and the environment. Denitrification convert nitrate to nitrogen gas. The sequence is as followed-Nitrate (NO3)→Nitrite (NO2)→Nitric Oxide (NO)→Nitrous Oxide (N2O)→Nitrogen Gas (N2). The second zone is Aerobic, which it needs oxygen. This zone creates nitrification just Extended Aeration like the extended aeration process: Ammonia (NH3)→Nitrite (NO2)→Nitrate (NO3) and North Wastewater Treatment Plant this occur due to two microorganisms known as Nitrosomonas and Nitrobacter. When the wastewater reaches the end of the aeration basin, it discharges into the clarifiers where the North Wastewater Treatment Plant (NWWTP) is a 15 million gallon per day (MGD) water and solids separate. The clarifier holds up to 1.5 MG of water. The water flows to biological process in the treatment of wastewater disinfection basin where the water will be disinfected with ultraviolet light, once disinfected (sewage) known as Aerobic Activated Sludge the water will be sent to the golf course ponds where they will use the reclaimed water for Extended Aeration (EA). The process adds irrigation; also, reclaimed water will be sent to reclaimed water clarifier. This water will be dissolve oxygen (DO) in the aeration basins to the used at the SWWTP for irrigation and washing down certain parts of the facility. If the disinfected water is discharge in the drain ditch it is known as effluent. The solids are sent wastewater coming in known as influent to keep the to the digester and thickener. During this process dissolved oxygen is still added, so it does good bacteria alive. Nitrification happens in the not turn anaerobic. aeration basins, which is Ammonia (NH3)→Nitrite (NO2)→ Nitrate (NO3) and this occur due to two microorganisms known as Nitrosomonas and Nitrobacter. When the wastewater reaches the end of the aeration basin, it discharges into the clarifiers where the water and solids separate. The clarifier holds up to 1.5 MG of water. The water flows to disinfection basin where the water will be disinfected with ultraviolet light, once disinfected the water will be sent to the pond and clarifiers for storage. This water is known as reclaimed water. Reclaimed water is also known as recycle water or reused water. Reclaimed water will be used for irrigation purposes. If the disinfected water is discharge in the drain ditch it is known as effluent. The solids are sent to the digester and thickener. During this process dissolved oxygen is still added, so it does not turn anaerobic. Anaerobic is without oxygen and bacteria will die causing the solids to become septic. The solids will be sent to the belt presses or drying beds where it will be dewatered more and eventually dry and turn into sludge. The sludge will be transported to a farm where it will be used for fertilizers.

This is just a snap shot of what a North Wastewater Treatment Plant does, there so much more in the biological process and chemical process that I hope it fascinate you enough to take an interest in the Water and Wastewater profession.

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