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.

Anaerobic Wastwater Treatment, Fall 2013

Ge Gao, Maithili Gokarn, Walker Grimshaw, Caitlin Rose McKinley, Liankun Zhu

Abstract:

Wastewater treatment is an important issue worldwide. Over one billion people across the world have connections to disposal methods for wastewater that remains untreated and instead is directly deposited into the environment, posing great human and environmental health risks. This research represents a union of the AguaClara program at Cornell and the Richardson Lab, with the long term goal of developing a gravity driven system for wastewater treatment and to characterize the general mechanism for anaerobic waste treatment. This team has and will operate under the principles of reducing human impact on the environment by effectively treating domestic wastewater before reintroduction to natural bodies of water and treating waste as a source of energy rather than a sink. Anaerobic treatment methods have been identified as the most appropriate for use in the global south due to their small footprint, low energy requirements, and slow rate of biomass growth. This semester six lab-scale reactors were constructed and operation begun to determine methods for controlling waste treatment efficiency and methane capture. Full scale reactors will use the methane produced within as an energy source to make the waste treatment an energy neutral or energy positive process. Of the six reactors, three were Anaerobic Fluidized Bed Reactors (AFBR) and three were Upflow Anaerobic Sludge Blanket (UASB) reactors. Though the reactors were only operated for a short period of time, they will continue to be operated in the future while data is collected for Chemical Oxygen Demand (COD) removal in addition to biogas production and specifically the methane levels within this biogas. One mathematical model was developed this semester to understand the fluidization characteristics of bio-granules as they develop on support media in the AFBR reactors. This model influenced the decision to use 0.1 mm quartz powder as a support media, and tests will be performed in the future to ensure this model corresponds with the fluid dynamics within the reactors. Microscopic techniques were investigated to determine their efficacy for elucidating the orientation and activity of microbial populations within the anaerobic granules. It is likely these techniques will be used in the future along with quantitative PCR techniques to understand the granules better. Other short term objectives for the study of wastewater treatment in the global south are to reach steady state operation of the reactors in terms of methane production and COD removal and exploration of new influent geometries to best fluidize the sand bed with such small support media.

Turbulent Tube Flocculator – Fall 2013

Felice Chan, Jonathan Christensen, Stephen Jacobs, Ana Oliveira

Abstract:

The purpose of our research is to design, build, and eventually test a lab scale turbulent tube flocculator. This is important because while the AguaClara plants in Honduras and India have flocculation that occurs in turbulent 􏰃ow, the prior AguaClara program research has focused on laminar tube flocculators. Thus, with the turbulent tube flocculator experimental apparatus, future AguaClara researchers will be able to more accurately conduct research to perfect the design of the full-scale plant. The prior literature that proved most relevant related to either the materials needed for the turbulent tube flocculator to be built or the size of eddies necessary for flocculation.

The 2013 summer semester AguaClara team's design for the turbulent tube flocculator was that the flocculator should be a vertical single coiled tubing configuration. The design used two pairs of pipes to constrict the tube in the coil to create turbulent eddies. The main goal of the Fall 2013 team was to perfect the initial design created in the summer of 2013 and then build the turbulent tube flocculator.

Sand Source and Testing - Fall 2013

Rebecca Schneider and Meghan Furton

Abstract:

The Sand Source and Test Methods sub-team is new to AguaClara this semester. Our main sources of research come from the known SRSF sand constraints, which dictate that no sand should be able to slide through the 0.2 mm slots in the PVC pipe, the sand should be hard and not prone to dissolution in acid, the backwash velocity required to expand the filter bed by 30% should be very close to 11 mm/s, and the sand bed must not have significant stratification after backwash. In addition to the constraints provided by the SRSF, the filter sand used must also satisfy American Water Works Association guidelines (AWWA). We are using American Water Works Association (AWWA) media constrains along with the American Society for Testing and Materials guidelines (ASTM International) to compile a series of test methods for filter sand. We intend to determine which of these constraints apply to the SRSF design. Furthermore, progress towards local sand acquisition is varied between the sites in India and Honduras as of September 2013. In India, sand is currently taken from the Barakar river and the only modifications made are sieving it for correct size on site, using two large rectangular mesh sheets that are shaken by two people. The two sieve sizes currently in use are No. 60 and 30, which correspond to particle sizes of 0.25 mm and 0.5mm respectively. There is also potential access to laboratories in the Universities and NGOs nearby. In Honduras, on the other hand, there is not an established sand mine industry and sand will likely be taken from river beds near the site. Transporting this sand from the river to the site is easy, but testing will be done in the apartments without the use of laboratory equipment that is difficult to transport.

Foam Filtration - Fall 2013

Skyler Erickson, Melissa Shinbein, Jeffrey Suen, Kadambari Suri

Arsenic, Fall 2013

Tanapong Jiarathanakul, Imtiaz Karim, Michelle Wagner

Abstract

The AguaClara Arsenic team for the Fall 2013 semester is the first to begin testing different methods of removing arsenic from drinking water. The initial goal was to develop a reliable method for testing water treatment alternatives and be able to detect small concentrations of arsenic. The work this semester follows the literature review performed in Spring 2013 which evaluated alternative arsenic testing methods and water treatment options for arsenic removal. A key issue is the need to measure low levels of arsenic (below ten parts per billion). Over the summer a graphite furnace atomic absorption spectrophotometer (GFAAS) was repaired for use in arsenic analysis. The lamp and power source of GFAAS have been replaced to improve the arsenic detection limit and the team is learning to operate the instrument. We will be using different coagulants to see which provides the best adsorption of arsenic to remove it from water, and dierent sample processing methods to simulate larger scale treatment processes. The team has a designated area for handling the solutions and samples as arsenic is toxic and we would like to minimize the contact it has with any person or object in the lab. The issue of arsenic waste is also a concern and this is why we are performing experiments using small sample volumes in order to reduce the amount of toxic waste produced.

Fall 2013 Chemical Dose Controller

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 influnt 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 flouroelastomer seals that are more resistant to cholrine 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

Ram Pump - Fall 2013

Ruben Ghijsen, Madeline Haas, Kelly Huang, Ariel Seidner

Abstract:

AguaClara creates sustainable water treatment plans that are powered entirely from the force of gravity and hydraulic principles, making them completely electric-free. However since plan outlets are located at much lower elevations than the plant itself, this presents difficulties in transporting treated water back into the plant for filling chemical stock tanks and plumbing. The ram pump is an excellent solution because it utilizes the water hammer effect to pump water to a higher elevation than the source water and does not use electricity. Our ram pump is designed to be augmented in an existing plan in San Nicolas, Honduras, where the 750.0 L stock tanks will need to be filled in 3 hours, corresponding to a flow rate of 70.0 mL/s.