Acid Neutralizing Capacity, Fall 2010

Drew Hart, Roy Guarecuco, Larry Lin

Abstract:

In light of recent successful tests run by the AguaClara Engineers in Honduras with poly-aluminum chloride (PAC), an alternative coagulant to alum which consumes a fraction of the alkalinity, the ANC Control team is preparing to stop research with lime feeders because they will be largely unnecessary when PAC is adopted for all AguaClara designs. In order to bring closure to ANC research the team will write a final paper detailing the insights pertinent to lime feeder technology that AguaClara has gained over five semesters of research. We will also organize the ANC Control wiki page

Chemical Dose Controller, Fall 2013

Zeyu Yao, Saugat Ghimire

Abstract

The Chemical Dose Controller is an important of component of a AguaClara plant. The CDC delivers the coagulant (Polyaluminum Chloride (PACl) or Aluminum sulfate (Alum)) to the influent water and disinfectant Calcium hypochloride to the effluent filtered water. The Chemical Dose Controller is a simple mechanical response device which maintains a linear relationship between the plant flow and the chemical dose. It consists of a calibrated lever arm which the operator can use to adjust the dose of the chemical based on the turbidity of the influent water. The Fall 2013 team started off by putting together three half size doser units for stacked rapid sand filters constructed in India. All the parts were shipped to India with a detailed instruction manual to aid the assembly. The dosers sent to India contained CPVC ball valves with fluoroelastomer seals that are more resistant to chlorine than the previously used PVC ball valves. The ball valves in all the AguaClara plants will now be replaced with these CPVC ball valves. Similarly, a lock-and lock container will now be used as the Constant Head tank for both chlorine and coagulant suspended with a chain and a turnbuckle for height adjustment. Although the lock-and-lock container degrades when in contact with chlorine, it is locally available and can be easily replaced. In addition to this, the design of a new half-size doser with single arm which only doses chlorine has been completed. A 3D sketchup file has been created and sent to Hancock Precision for fabrication. This new doser will primarily be used in low flow plants in India which only require chlorine delivery.

Unit Process Analysis: Coagulant - Fall 2019

Ada Lian, Sarah Paquin

Abstract:

The Fall 2019 Unit Processes Analysis Coagulant (UPAC) team’s objective is to reduce capital and operating costs and improve particle removal efficiency for the AguaClara water treatment process, specifically by analyzing the response of the system to varying coagulant dosage. To analyze the system response, we will run a series of trials on a treatment plant sedimentation model, varying the coagulant dosage and recording observations regarding the effluent turbidity, floc formation, and floc blanket formation. Through this experiment, the team will be able to establish a minimum coagulant dosage, which could lower operating costs, and to learn valuable information about the interactions between coagulant and the primary particles of the influent water at high coagulant dosages.

Contact Chamber - Fall 2017

Cheer Tsang, Yeonjin Yun, Ben Gassaway

Abstract:

The introduction of coagulant into turbid water causes collisions of suspended particles with coagulant nanoparticles, which promotes the growth of flocs. However, a large portion of the coagulant dose adheres to pipe walls rather than influent particles, requiring a higher than necessary coagulant dose to account for this effect. In order to minimize coagulant waste, an apparatus called the contact chamber was fabricated to increase collisions between influent particles and coagulant. The Fall 2017 Contact Chamber team analyzed the performance of the contact chamber by comparing influent and effluent turbidity in experiments with and without a contact chamber. After several trials, it was concluded that the contact chamber did not improve the effluent turbidity. In fact, the effluent turbidity with the contact chamber was significantly greater than the effluent turbidity without the contact chamber.

Fluoride - Fall 2017

August Longo, Victoria Zhang, Michelle Cheng

Abstract:

The Fluoride subteam seeksto dvelop a sustainavble, inexpensive fluoride removal system for implementation in upcoming AguaClara plants located in India. After earning an EPA Phase II grant for the Spring 2016 fluoride remocal reactor, the subteam continued to improve fluoride purification by testing lab-scale systems consisting of either a single reactor or two reactors in series. During the experimentation process, clay was incorporated into the influent stream to abate PACl buildup at the bottom of the reactors. As the subteam seeks to transplant their system to India, it is currently working to optimize fluoride removal by minimizing use of resources. Thus, the team is currently trying to eliminate the use of clay and lower PACl dosages by increasing upflow velocity and further redesigning its reactor. Initial tests suggested insufficient fluoride removal for potable effluent, but the team is looking to repeat its previous experiments using the summer 2017 High Rate Sedimentation subteam’s reactor design