Engineering Research

2017 Topic: Acid Neutralization Tank


Wastewater from high school science laboratories and prep rooms is typically pretreated before being sent off-site.  An acid neutralization tank is a typical part of that process.  According to the New Jersey Department of Environmental Protection (NJDEP), ”a Pretreatment Program is an important function protecting local sewage treatment plants from non-domestic wastewater which may interfere with treatment processes, contaminate sewage sludge, or pass through sewage treatment plants.”


Students teams will design and test a five gallon model scale acid neutralization tank that will effectively neutralize acidic water with an original pH of 6 to an unknown target pH between 7 and 8. The system should include the following:

  1. The model tank should be made using a 5-gallon plastic bucket containing three (3) gallons of tap water that has been lowered to a pH of 6.
  2. The tank will have an unobstructed output valve positioned so that when additional water is added to the three gallons, this effluent is automatically discharged from the system.
  3. The tank can be stirred continuously with the addition of the neutralization materials. The stirring may be manual or automatic.
  4. The connection for the output valve MUST be a ⅜ inch hose barb.
  5. The discharged effluent should maintain a pH between 6-8 while trying to achieve the target pH.  
  6. No strong bases may be used for neutralization.
  7. Teams will monitor the discharge effluent of the acid neutralization tank with a pH meter.  The effluent will be monitored for the time it takes to achieve a target pH and how close and consistently the team achieves the target pH.  


Part 1 - Conduct literature research and investigate research to address the following:

  • What chemicals are typically used in neutralization tanks?
  • Research applications of Feedback and Control systems in engineering.  Describe how an acid neutralization tank fits this model.
  • What is the pretreatment process in your school and/or another industrial facility. Discuss how industrial applications may differ from that used with wastewater treated from a high school.

Part 2 - The Engineering Process

This event focuses on students demonstrated use of the engineering process to show how the team came to the final acid neutralization tank chemical application decisions that are presented on the NJCO Event Day.  Student teams should investigate how pH of effluent vs. time is influenced by the following factors:

  • Varying additive base pH or volume
  • Varying flow rate and/or stirring rate

Students are encouraged to use the following resources to learn about the engineering design process and prior to beginning, consider a way to document the process that they can be shared with the judges.  

Part 3 - Report of Student Findings:

1.  A research paper should be written that demonstrates the team's understanding of the following:

  • Describe the chemical processes and thermodynamic considerations associated with acid neutralization typically found in acid pretreatment systems.  
  • Describe how feedback and controls can be applied to the design considerations of an acid neutralization tank.
  • Discuss the workings and limitations of the acid neutralization tanks typically found in a high school pretreatment system and/or other industrial facility.
  • Compare/contrast the use of strong bases vs. specific carbonate compounds in terms of specific design decisions.

An Appendix 1 should be included that shows documentation of the Engineering Process the team followed. (Format determined by team - photocopied Lab Journal is acceptable) and the Safety Plan the team has followed. The safety plan should elaborate on team's effort for safe chemical handling and disposal.

2.  A video of a working trial of the acid neutralization tank should be made and posted to YouTube to share with the judges before the Event Day. The video should clearly state where in the design process the team has progressed. The URL of the video should be sent along with the team’s research paper. - This video does not have to demonstrate the final working model, but should demonstrate a functioning model at the most basic level.

Event Day

All teams will present their engineering design process to the judges in a short Powerpoint focusing on the major design changes in their prototypes. (2 minutes maximum)  This should include a short video demonstrating the function of their  Teams will participate in a short question and answer session with judges to share their design decisions in terms of addressing feedback and controls of their system.

Student teams will then present their neutralization model tank for testing. Judging of the demonstration will measure the pH of effluent output versus time.  Each team should bring a tank (the modified plastic bucket) with a ⅜ inch hose barb installed as overflow. The teams should also bring, or prepare on site, their neutralization solutions. The judges will supply the measuring container, the pH meter, and tubing to connect the tank to the measurement.


Safety Note:  All laboratory work should follow appropriate safety instructions and be supervised by instructor or coach. No strong acids or bases are required and therefore should not be used. Students must demonstrate proper safety when handling chemicals and chemical splash goggles are required during practice, video taping as well as for event judging.  Teams must have a proper safety plan in place.


IMPORTANT:  Learn about the requirements concerning Primary Sources, formatting and citations for your research paper: Research Guidelines and Requirements

The Engineering Research Paper must be received by the Director of the NJCO by the deadline indicated in: Requirement Overview.



​​None at this time.


  • Written Report and Video of Working Design– 20%
  • Rationale for Engineering Design Choices  30%
  • Oral Presentation / Evidence of Engineering Process – 30%
  • Achievement of Target pH  20%