Municipal Wastewater Treatment Plant Site Visit Report Thursday, October 2, 2014 Prepared by: Elora Arana, Environmental Studies student Prepared for: Dr. Heather Wilkinson, Professor BESC 489/411 Texas A&M Wastewater Treatment Plant 9685 Whites Creek Rd., College Station, TX. 77845 Background and Introduction The BESC Environmental Health, Safety and Compliance class traveled to the Texas A&M Municipal Wastewater Treatment facility on Thursday, October 2 nd, 2014 under the supervision of Dr. Heather Wilkinson to examine Texas A&M University s municipal wastewater treatment facility. The facility is a conventional activated sludge treatment plant that was created to treat wastewater from the university as it grew too large to be serviced by the College Station Municipal Wastewater Treatment plants. The plant is designed to treat 11,700 lbs. BOD/day on a maximum monthly average, a population equivalent to servicing 69,900 people. Load varies dramatically with student population fluctuations during the academic year. Preliminary treatment occurs once waste reaches the facility. Large, untreatable debris is screened from the waste, such as toilet paper and whatever else can end up in a sewage line, using a Mechanical Bar Screen that removes debris from the incoming stream by scooping it out mechanically. Grit and other heavy mineral matter found in the wastewater that will not decompose during treatment is removed using a Vortex Grit Removal System to ensure that heavy material will not negatively affect equipment in the facility. Primary treatment begins with the primary clarifier, where gravity assists in separating settled and floating solids from the liquid. This liquid then flows to the aeration basin while pumps in the primary pump station send the separated solids, herein known as sludge, from the clarifier to thickeners or anaerobic digesters for further processing. Secondary treatment begins when the aeration basin mixes the liquid from the primary clarifier with sludge from the secondary clarifier using blowers that feed the microorganisms oxygen to assist in metabolizing remaining impurities in the liquid. Blowers also assist in distributing the microorganisms in order for them to come into contact with dissolved organic matter in the water. Water then flows to the secondary clarifier where solids and liquids will further separate through gravity sedimentation. Some of the sludge that is collected here is returned to the aeration basin to continue to introduce fresh microorganisms to incoming waste needing biological treatment. Treated water is disinfected before being discharged using UV light to destroy the cells of any remaining organic material in the water. After the UV disinfection, water is discharged to the Brazos River through a 36 outfall line. Collected sludge from anaerobic digesters holding tanks is removed and used for biosolids land application to the area surrounding the facility. 1
Figure 1 Wastewater Unit Process Diagram Processes with potential for pollution Land application and recycling of biosolids from collected sludge could pose potential for abnormally high levels of metals and other toxins and nutrients remaining in the sludge that is applied to the land surrounding the facility. This is monitored through soil sampling around the plant. An annual report of the soil samples must be submitted to TCEQ to prove that there is not any excessive soil contamination. Land application of biosolids also poses a potential for runoff into the nearby creek if not applied and allowed to settle properly. Application should not occur before or after a rain event, cannot be applied to a wet surface and applied biosolids must settle into the ground after application. Runoff could lead to potential toxic pollution of the water system and unsafe environments for aquatic life in the water. Figure 2 Terragator used to plow sludge onto field surrounding plant. Holds 2,000 gallons of sludge material. 2
The facility produces stormwater pollution when it receives stormwater through natural events because it is not permitted to receive and process this type of water. When an event does occur, plant operators let the state know when here is a potential for stormwater pollution. When any part of the treatment process does not work as it should, it could result in water not meeting standards being discharged to the Brazos River. We consider this treated water pollution because some or all of the water has been processed through the plant and still contains effluents that are being released back into an open system. Operators monitor for this type of pollution at the point of discharge (see figure 3) through daily sampling and can adjust and find problems in the system based on sampling results. Figure 3 Point of discharge through 36 outfall line after UV disinfection Direction of flow into outfall line Chemicals used at the facility Sodium hypochlorite (also known as liquid bleach) is used in this facility to disinfect nonpotable water being used for different processes thoughout the plant. 3
Figure 4 Containers of Dixichlor sodium hypochlorite on site Figure 5 Non potable water line connecting to the aeration basin for diluting and aeration purposes 4
Pollution Control and waste minimization (air, toxics, water, waste, etc.) The entire facility is intended for municipal wastewater pollution control. The facility does employ the practice of reusing and recycling accumulated sludge from the process through land application to minimize biosolid waste that would otherwise be shipped to a hazardous waste facility for further treatment. This process saves the facility money in outside shipping and disposal costs. Also provides surrounding land natural fertilizer to stimulate plant growth and ecological health. Sampling the water being discharged from the facility and the soil from the land that is being plowed with the biosolids sludge are pollution controlling mechanisms. They allow the facility to monitor how efficient the treatment process is working, and also prevents toxins and unnecessary nutrients from being discharged or applied to the land that could potentially harm the environment, wildlife and humans. Relevant state and federal regulations associated with the site This wastewater treatment facility is regulated by the TCEQ and EPA. The following state and federal regulations are associated with the monitoring and permitting of the processes at this facility: Texas Pollution Discharge Elimination System (TPDES) o Currently in process of re submitting and approval of new permits by TCEQ in preparation for current permit expiration o Allows a wastewater facility to discharge treated effluent into a body of water in the state of Texas. National Pollution Discharge Elimination System (NPDES) superseded by TPDES because of stringency o Allows a wastewater facility to discharge treated effluent into a body of water in the United States. 30 TAC, Rule 312.82 o For the use, disposal an transportation of sludge and pathogen reduction Water Quality Management Plan (WQMP) o Defines the state s water quality assessments that identify priority water quality problems o Direct planning for implementation measures that control and/or prevent water quality problems o Used to implement measures to monitor, control or limit water source pollution Texas Land Application Permit (TLAP) Required monitoring 5
Quarterly sampling of sludge Daily testing of ph and dissolved oxygen (manually) Effluent testing done in laboratory in house (figure 6) Figure 6 In House laboratory for small scale monitoring and sampling Figure 7 MSDS chemical safety documentation, sampling data and images of microorganisms posted around main office for reference 6
Automatic daily sampling of BOD (biochemical oxygen demand), TSS (total suspended solids) and ammonia nitrogen Heavy metals from biosolids land application o Done by third party contractor Flow monitoring o Daily o Long term (over several months) If process flow exceeds 3 million gallons, or 75% of capacity, for 3 or more months, facility must begin planning for a new plant Oxygen levels in aeration and anaerobic basins and tanks o Aeration basins need to have between 1 2 ppm of oxygen in order to metabolize biological waste properly Figure 8 Bubbling (effective) oxygenation in aeration basin 7
Report schedule This facility sends monthly reports of a variety of data sampling and monitoring results to the TCEQ. Also submits and annual report on soil sampling around the facility. The actual sampling is contracted out to a third party contractor that comes in and drills hundreds of holes for sampling sets in the land surrounding the facility where the biosolids are plowed. General Comparison to a municipal or industrial version of this entity This is a 4 million gallon plant that serves the Texas A&M population and all users of facilities at Texas A&M and a few nearby facilities that also flow into the Texas A&M wastewater collection basin. 90 95% of flow comes from the university and is on average servicing almost 70,000 people during a normal period in the academic year. Most fluctuations in flow rate occur with game days, special events and holiday breaks. This facility runs smaller operations than a full scale municipal wastewater treatment plant, but it also handles flows attributed to moderately sized municipalities. How these distinctions affect the threshold for regulation of this entity (e.g. is it smaller than most and therefore requires less monitoring?) The larger the wastewater treatment plant gets, the stricter and more stringent the regulations tend to be, which leads to increased monitoring, sampling and reporting. There also tends to be more problems associated with larger plants and having more deviations against their permits due to the increased number of sources of wastewater flow. The permits for his plant are based on the watershed size that it discharges into, the population size served and the processes that it is capable of handling. References Cited "Sewage Sludge: Am I Regulated?" TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wastewater/wastewater/sludge>. "Domestic Wastewater Permits." TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wastewater/wastewater/municipal/wq_domestic_w astewater_permits.html>. 8
"Domestic Wastewater Permits: The Permitting Process." TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wastewater/municipal/wq_domestic_wastewater_p ermits_steps.html>. "Wastewater and Stormwater Permits and Registrations." TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wastewater/water quality>. "Water Quality Management Plan." TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wqmp/wqmanagement_definition.html>. Primer for Municipal Wastewater Treatment Systems. Washington, DC: U.S. Environmental Protection Agency, Office of Water, Office of Wastewater Management, 2004. US EPA. Web. 9 Oct. 2014. <http://water.epa.gov/aboutow/owm/upload/2005_08_19_primer.pdf>. "Wastewater (Sewer) Services." City of College Station: Wastewater Services. City of College Station. 9 Oct. 2014. <http://www.cstx.gov/index.aspx?page=818>. "Wastewater Treatment." City of College Station. 9 Oct. 2014. <http://cstx.gov/index.aspx?page=820>. "Available Water Quality General Permits." TCEQ. 9 Oct. 2014. <http://www.tceq.state.tx.us/permitting/wastewater/wastewater/general/index.html>. "Texas Administrative Code." State of Texas. 9 Oct. 2014. <http://info.sos.state.tx.us/pls/pub/readtac%24ext.tacpage?sl=t&app=9&p_dir=n&p_rloc=176 49&p_tloc=&p_ploc=1&pg=2&p_tac=&ti=30&pt=1&ch=312&rl=82>. 9