Filter Media Treatment – Fall 2011

Po-Hsun Lin

Abstract:

The post sedimentation addition of polyaluminum chloride (PACl) was investigated as a means to enhance particle removal efficiency in rapid sand filtration. The process modification was evaluated in laboratory studies and at the Cornell Water Filtration Plant (CWFP). PACl was continuously metered into CWFP filter influent to increase concentrations by 0.06 to 4.2 mg/L (as aluminum) during the filter-to-waste stage of the filter operation cycle to accelerate filter ripening. Lower influent PACl concentrations ranging from 0.056 to 0.43 mg Al/L were also continuously applied during filtration. In comparison to a control filter that received no PACl addition, the ripening time required decreased with PACl dose, and the incremental improvement in particle removal during filtration increased with PACl dose. The addition of 0.056 mg Al/L of PACl (the lowest concentration tested) significantly reduced initial filter ripening time at the CWFP from 10 hours to 2.5 hours, and effluent turbidity in the test filter over the 77 hour filter run was lower than the control filter by an average of 17%. Incremental head loss increase caused by the PACl feed was dose dependent and was negligible for the lowest dosage tested.

Turbidimeter, Fall 2011

Julia Morris, Andrew Gorodetsky, Heidi Rausch

Abstract:

This report will cover all the work that has been done by Cornell’s AguaClara program on turbidimeters. Research first started on creating a new, low cost turbidimeter at Cornell in the Spring of 2011. Since then several different prototypes have been created and ten turbidimeters have been sent to Honduras for use by communities who are considering building an AguaClara plant. The reason that a low cost turbidimeter needs to be developed is so that communities who may be in need of water treatment facilities can test their water without incurring the high expense of other turbidimeters currently on the market. The most current complete turbidimeter prototype can read NTU values down to 15 NTU. The research discussed in this report details new turbidimeter designs with which it may be possible to read NTU values down to approximately seven NTU. The most promising design includes the use of a blue LED light and a large HDPE block, which is used for diffusing the light. However, this design will need to be tested more thoroughly for accuracy before it can be fabricated for use in the field. In the future if research continues to be done to try to create a turbidimeter that can read turbidity values below 5 NTU the length of the lowering rod may have to be made longer than the current prototype, which is only 60 cm long. Without adding length to the lowering rod current research suggests that it may be impossible to read the turbidity of any water with an NTU value lower than seven.

Water Treatment Technology Selection Guide, Fall 2011

Mary John, Caroline Caglioni, Savannah Wing

Semester Goals

The purpose of the team this semester was to create professional, consistent material that can be used to explain the AguaClara technology to other engineers, using photographs, diagrams and concise descriptions. By the end of the semester the team has produced documentation that can be taken to any conference or seminar, sent anywhere to any engineer, that presents AguaClara as a professional organization. The team has created “white papers” for the general AguaClara technology, the Chemical Dose Controller, the Foam Filter and the Educational/Organizational model. In addition, the AguaClara logo was revised, templates were created for consistent future white papers and the website was redesigned.

Plate Settler Capture Velocity, Fall 2011

Ruonan Zhang, Xiaocan Sun, Yizhao Du

Abstract:

Through lab research we seek to understand the different influence of coagulant type, capture velocity, coagulant dose and raw water turbidity on the performance of the plate settler in AguaClara plants. We are using a tube settler to simulate those plate settlers in the full-scale plants. Through various changes in operating conditions, we expect to determine the best parameters, and this is of great significance in real practice. After that, we are going to pick out some of the best conditions and repeat the experiments with natural organics in order to see how humic acids affect overall performance.

Chemical Dose Controller, Fall 2011

Jordanna Kendrot and Frank Owusu-Adarkwa

Abstract:

Continuous and accurate chemical dosing in water treatment plants is required for optimal efficiency during flocculation, sedimentation, filtration and disinfection. AguaClara designed the linear chemical dose controller (LCDC) and the Linear Flow Controller (LFC) systems to allow plant operators in Honduras to easily set and maintain the dose of coagulant and disinfectant through one system. A linear relationship between the head lost and chemical flow is created by using only major head loss, where the flow is controller by a small diameter tube. To continue using this linear relationship, the current experimental system has been designed with the goal of eliminating minor head loss. Our team is actively working towards the continuation of this work, decreasing the minor head losses throughout the systems, reducing the systems maximum percent error under 10% and standardizing the components and calibration techniques that will be used to fabricate this system in the field.

Sedimentation Tank Hydraulics, Fall 2011

Jill Freeman, Mahina Wang, Saied Khan, Matthew Hurst

Abstract:

A floc blanket is a dense, fluidized bed of particles that forms in the sedimentation tank and helps to reduce effluent turbidity by trapping small flocs and reduces clean water waste through less frequent draining of the sedimentation tank. Floc resuspension is necessary for floc blanket formation so that flocs are recirculated through the tank instead of settling on the tank bottom as sludge. Research was conducted to examine mechanisms for floc resuspension. Parameters important for floc resuspension include energy of the jet stream on its upward flow path, position of the jet as it interacts with solids, and hydrodynamic pressure of the jet compared to hydrostatic pressure of the returning solids. Several geometries were tested with red dye and fully built floc blankets to observe the jet path and velocity profile around the bottom geometry. Best results are achieved through geometries that preserve jet momentum, especially through splitting the jet flow, and geometries that maintain a high jet velocity when contacting solids. Later, quantitative measurements were taken to determine floc blanket performance for various bottom geometries.

Residuals Management, Fall 2011

Patrick Farnham

Abstract:

The Residuals Management sub-team is solving the problem of solids disposal in AguaClara treatment plants. Currently, settled solids from the sedimentation and entrance tanks are drained and routed directly onto the nearby landscape. The newly created stacked rapid sand filtration system will produce backwash water in need of disposal, and spikes of highly turbid influent water bypass the plant by being discharged down the surrounding slope. The research goal is to determine inexpensive and responsible disposal methods for these outflows as well as for precipitate matter removed from the chemical stock tanks. Flow rates and concentrations of all residual flows have been estimated with the help of AguaClara engineers in Honduras, and designs have been created for pipe outlet protection structures which should reduce the erosive power of AguaClara residual flows. The team goal is to identify promising methods and eventually code them into the AguaClara design tool for use in the future and also for possible use in retrofitting current plants.

Foam Filtration, Fall 2011

Bradshaw Irish, Anna Lee, Rachel Philipson

December 12, 2011

Abstract

The Foam Filtration team is attempting to determine an application that utilizes polyurethane foam as a water filtration medium. Our work consists of running experimental trials which characterize the filtration properties of polyurethane foam. Polyurethane foam is not a conventional filtration medium, and through extensive work, we have proven that it can successfully produce effluent turbidities below US EPA standards. In addition to the characterization of foam as a filter medium, we have previously investigated the possibility of utilizing polyurethane foam at the point-of-use scale. A feasibility study determined that a polyurethane foam point-of-use unit would require the addition of coagulant and expensive moving parts. Therefore, the new focus of the Foam Filtration research team is on the design of an emergency water treatment system using polyurethane foam. This unit will consist of a roughing and finishing filter. Previous research characterized the performance of the finishing filter and current laboratory tests are focused on evaluating performance of the roughing filter.

Demo Plant, 2011 Fall

Breann Liebermann, Sahana Balaji, Muhammed Abdul-Shakoor

Abstract

The technology behind the AguaClara water filtration process features filtration through coagulation, flocculation, and sedimentation and flow/chemical dose control using gravity. Currently, an LFOM has been fabricated and tests have been done to see if a linear relationship exists between flow rate and height of water. Final touches will be put on the chemical doser. Currently, we are in the middle of fabrication of the sedimentation tank and tests will be done shortly to see if a floc blanket can in fact form.