Laminar Tube Flocculator, Fall 2012

Patience Ruijia Li

Abstract

According to the predictive occulation model proposed by Swetland et. al., 2012, large ocs do not signicantly contribute to turbidity removal  only small colloids can collide eectively and aggregate to a size that will be removed by sedimentation. Based on the hypothesis that large ocs are useless, a oc breakup procedure was devised. Results obtained using a coiled tube occulator and occulation residual turbidity analyzer (FReTA) shows that higher turbidity removal was achieved after breaking the ocs, comparing to results using the same method but without oc breakup. Therefore breaking ocs at regular intervals to maintain continuous growth will promote better performance of occulation. This research nding provided a good reference for future hydraulic occulator design.

Smart Phone Turbidimeter, Fall 2012

Abstract:

An open-source, low-cost turbidity meter.

The high cost of equipment to monitor water quality often puts valuable health tools out of reach for many communities in developing countries. Our low-cost device measures the turbidity, or "cloudiness", of water due to suspended particles, and can detect potentially dangerous concentrations of dirt in water -- even when they are invisible to the human eye! Our device integrates with a remote data-acquisition system to enable record keeping and real-time observation of water quality in rivers, wells, and treatment plant

Sedimentation Tank Hydraulics, Fall 2012

Frances Ciolino, Hongyi Guo, Ethan Yen

Abstract:

The sedimentation tank hydraulics team this semester focused on optimizing the floc hopper. Our main goal was to learn more about the floc hopper geometry and reasons for floc blanket failure. We started the semester by looking at the vertical sedimentation velocity. This velocity is controlled by the flow into the tank and affects how fast the particles settle. If this velocity is too high or too low, the sedimentation tank will not form a proper floc blanket.

We also looked into how the plan view area of the floc hopper would effect the floc blanket formation and performance. Changing the size of the floc hopper effects how much of the area allows for up-flow of the water and how much captures the flocs. In our current experiments we are trying different sizes at different wasting rates. We are looking for a size and rate that keeps the plant running efficiently, meaning the least amount of water wasted while keeping the water leaving the plant clean.

One of the ideas we are working on is continuous wasting of the flocs. The idea behind this is to allow for constant removal of flocs instead of collecting the flocs and then manually opening a valve to let them leave the tank. When the wasting rate is optimal, the flocs will be allowed to compact before they are removed so that the least amount of water is lost in the process. Our last experiment looked at finding the proper wasting rate where the rate of particles flowing into the floc hopper is the same as the rate at which the particles are being removed.

Chemical Dose Controller, Fall 2012

David Buck, Andrea Castro, Rudra Koul

Abstract:

Accurate chemical dosing is an essential part of an AguaClara plant. Proper dosing is required for effective flocculation, sedimentation, filtration and disinfection. Coagulant (Poly Aluminum Chloride or Alum) and disinfectant (Chlorine) are chemicals used for dosing in an AguaClara plant. The linear chemical dose controller (LCDC) automatically maintains a linear relationship between the influent 􏰂ow to the plant and the chemical dose. The plant operator therefore only adjusts the dose of coagulant based on the turbidity of the influent water. Previous designs for the LCDC functioned at lower flow rates, but design changes were necessary for increased flows and dosing of two chemicals: a coagulant and a disinfectant. The Fall 2012 team created and refined a prototype of the proposed dosing system design. Also, the team concentrated on system aesthetics by: creating a new counter weight, engraving the lever arm scale, adding an engraved AguaClara logo and anodizing the lever arm assembly. Once complete a refined calibration method was devised and documented and the system was tested for linearity of the chemical dosage with respect to the dosing scale and linear flow orifice meter (LFOM) height changes due to varied plant flow. Both tests resulted in a linear fit with an R2 value of 0.9967 for the chemical dose percent data and an R2 value of 0.9955 for the plant 􏰂ow height data. The maximum percent error in the linear relationship between chemical dosing and dosing percentage was 63%. The maximum percent error in the linear relationship between chemical dosing and the LFOM height change was 34%. Errors were below the desired 10% at all data points except the data point corresponding to the lowest chemical dose, which suggests that the LCDC maintains a linear relationship at higher flows and is less accurate at low chemical flows. Error associated with chemical dosages with respect to the percent dosage can be attributed to the scale being offset from the zero (or pivot) point of the lever arm by approximately two centimeters. Error associated with changes in chemical􏰂flow rate with respect to changes in the plant flow rate can be attributed to the weight of the drop tube assembly.

EStaRS, Fall 2012

Mihir Gupta, Kris LaPan, Rachel Proske

Abstract:

The use of filtration units for the treatment of drinking water is a common practice in engineering design. However these units are generally used for the treatment of large volumes of water. To improve upon this limitation, a stacked rapid sand filter was designed for low 􏰃ow rates. Work for the semester began with an existing filtration unit which did not contain sand, due to predicted failure from large head losses in filtration and backwash. The existing design was modeled in AutoCAD 2013 to provide an illustration of the system. Updates to this drawing were completed and will continue to be as fabrication phases occur. One of the primary tasks was to develop a mathematical model in MathCAD to calculate the flows and head losses throughout the system. The model was completed for filtration and backwash, and includes calculations for both cycles with and without sand present. Hydraulic testing was completed to determine the head losses in filtration and backwash, risk of sand transport through the backwash pipe, and 􏰃ow rates. These measurements and observations were compared with the mathematical model to determine its validity. According to head loss values obtained from the mathematical model, several changes were made to the filter prototype. Such fabrications included complete reconstruction of the backwash pipe, changing of valve types, and installation of NPT fittings and ball valves. Finally performance testing was completed to determine the effectiveness of the prototype in regards to decreasing effluent turbidity. Overall, it was determined that the filter prototype is highly effective at decreasing turbidity for several influent concentrations at the designed flow rate.

Demo Plant – Fall 2012

Owen Guldner and Diana Kelterborn

Abstract:

The Demonstration Plant (Demo Plant) is an important educational tool to explain and publicize AguaClara technologies. In the Spring of 2012, a new Demo Plant was constructed, tested, and documented which included the two latest AguaClara technologies, a chemical doser and a stacked rapid sand flter (SRSF), as well as the older flocculator and sedimentation tank. In the summer of 2012 the demo plant structure and system was completely revised; the SRSF was fixed so that it can completely backwash all four layers, the chemical doser was labeled to include coagulant concentrations, and the overall plant was streamlined for transport and assembly. This semester we finalized construction materials and methods and built four more demo plants to be used at Cornell and abroad.