A brief description of each program task along with an estimated budget and schedule is provided below.
I. Regulatory
and Consulting Engineer Training Program.
II. Evaluation
of Non-Aligned Treatment Technology Program.
III. Innovative
Comparisons of Treatment Program.
IV. Costing
Summaries of New Water Treatment Technology Program.
Summary
I. Regulatory and Consulting Engineer Training Program. Engineers that are typically involved in either the design or regulatory approval process for small system treatment technologies do not frequent national or, in some cases, even regional conferences and workshops. Consequently, introducing new or innovative treatment technologies for small systems is frequently restricted because of the lack of knowledge on treatment processes that are not typically covered in formal engineering education classes. The principal objective of this program is to develop training materials in the form of CD-ROMs and a Web-Site on three water treatment technologies that are important for small water systems. The CDs (and web-site) will educate state and federal regulators and practicing engineers about these new treatment technologies and will provide a template for the design process.
The development of these water treatment technology CDs will be a collaboration between the University of New Hampshire (UNH) (Dr. M. Robin Collins) and the University of Tennessee (UTK) (Dr. R. Bruce Robinson). The structure and content of the CDs will be jointly developed. UTK will develop the agreed upon structure and content into a complete multimedia software package that will be written to a CD and require no special software to run. The development of the CDs will be accomplished through close communication between Drs. Collins and Robinson.
One of the three water treatment technologies to be developed for the CDs will be on slow sand filtration. The other two will be chosen in consultation with UNH. A likely second choice is iron and manganese control, but other choices may be either membranes or alternative disinfection processes important to small water systems.
The technology CDs will target an audience consisting of state and federal regulators and practicing engineers. The educational elements for each technology will include:
The CDs will be distributed through the Water Treatment Technology Center at UNH, and perhaps, by other means, e.g., at annual AWWA or regional conferences. Papers at conferences will also present the resulting software.
The estimated budget for this program is $122,499 and will require roughly 22 months to complete.
II. Evaluation of Non-Aligned Treatment Technology Program. Non-aligned technologies include those not associated with a specific vendor or manufacturer, and are consequently will most likely not be evaluated by the USEPA/NSF Environmental Technology Verification (ETV) Program. The initial testing for this program will include two such non-aligned technologies; slow sand filtration and river bank filtration. The former involves a constructed filter bed in which water passes through the sand medium slowly while the latter involves the same removal principles as the former except the filter bed is naturally configured from the native river bank. The major difference between the processes is that the clogged water-sand interface can be manually removed in a slow sand filter while the river bank filter must be periodically scoured by natural processes.
The evaluation of these technologies will be performed through side-by-side comparisons at field sites. Several candidate sites are under consideration for this testing, these include Milo, Maine, and the communities of Lancaster and Bethlehem in New Hampshire. Each of these sites have full-scale slow sand filters drawing source water from near-by streams. River bank filtration systems will be constructed at the selected site for direct comparison to the existing slow sand filter system.
1. Study Objectives
The primary objective of this evaluation is to compare river bank filtration to slow sand filtration in terms of:
In order to fully address the primary objective in the case of the river
bank filtration system, more information will be needed as to the mechanisms
of particulate and organic precursor removal, and the characteristics of
operation of the river bank filtration system. Therefore, several secondary
objectives will be addressed by this study. These include:
A river bank filtration system can be installed in either of two
types of hydrologic environments with respect to groundwater. These include
areas Where the river is receiving a constant influx of groundwater, and
areas where the water is infiltrating into the groundwater system. The
former condition, where groundwater is exfiltrating into the river, may
at times change to a condition where river water is infiltrating to the
groundwater system in times when the groundwater table fluctuations result
in a reversal of the groundwater flow, or during times of high river stage.
The last objective for the comparison is to evaluate the effect of the
hydrologic condition of the river bank filtration site on the comparison
of slow sand filtration to river bank filtration. In this case, the methodology
as described below will be repeated at a site with the opposite condition
as the first test site.
2. Methodology
This project methodology will contain five primary tasks. The first
task will be to design and install a river bank filtration well. The second
task, to be performed concurrently with the first, will be to design a
monitoring system which will enable the researchers to address the secondary
objectives as well as the primary objectives described above. The third
task incorporates a suite of pumping tests and the formulation of a computer
model to simulate the operation of the river bank filtration well. The
fourth task will be to install additional monitoring equipment as necessary
to fully evaluate the operating conditions, and the effectiveness of the
slow sand filter system. The fifth task will be to operate and monitor
both systems over one annual cycle. This task will be repeated for worse
case conditions at significantly different flow rates to examine the effects
of residence time in the subsurface on particulate removals.
Task 1: River bank filtration welt design and installation.
At each of the candidate sites, a full-scale slow sand filtration system is currently in operation. None of these sites have a river bank filtration well system installed. In order to perform a comparison, and address the secondary objectives of characterizing the river bank filtration system, a well system will be designed and installed at the study site.
The design will commence with a review of available hydrogeologic and hydrologic information for the selected site. Th/s information will include a review of well logs and/or test borings which may have been performed at the site, hydrologic testing (pump tests and slug tests) results in the same aquifer, soil survey information, bedrock elevation surveys, and flood flow frequency analyses. The review will extend to Federal and State agencies which may have sponsored studies in the area, as well as consultants. In particular, aquifer material descriptions, and aquifer properties will be researched. The office analyses will be used to design a pumping well and monitoring system for the river bank filtration system. If the required data for the design is not found, a limited field investigation will be performed using a small test well and small diameter monitoring wells to gather the required amount of data for the well design.
The system design will be based on the design flows currently produced
by the stow sand filter system. It is recognized that this design, depending
on the geohydrologic conditions of the site, may dictate the installation
of a multi-well field to obtain the required flow rate. In this case, one
well of the field will be installed and evaluated based on the respective
flow rate that this well would have as part of the overall well field.
Task 2: Design of monitoring well system for River Bank Filtration Testing.
This task will involve the design and placement of monitoring wells to address the distance/treatment correlation, and the evaluation of the groundwater component of the water coming from the production well. It is anticipated that conditions will allow the use of small diameter wells as monitoring wells. These wells consist of a 1.2-cm inside diameter pipe with four rows of longitudinal slots constituting the well screen. The screen lengths will typically be from 1 to 10 ft long, depending on the purpose of the respective well and the conditions found.
The monitoring wells will be placed at regular intervals between the pumping well and the river. Well clusters may also be installed, with two or three SDKs installed to different depths at the same location. These wells will be used to evaluate water quality along different flow paths from the river in a profile view. Wells will also be installed along lines parallel to the river, at increasing distances from a line drawn through the pumping well, perpendicular to the river. Several lines will be established at different distances from the river, to evaluate the extent of the zone of contribution from the river in the plan view. The wells will provide sampling points for water quality as a function of distance from the pumping well, and also along different three-dimensional flow lines from the river. This three dimensional approach will provide the means to evaluate if the zone of contribution is steady, or if it fluctuates. It is hypothesized that the zone of contribution will increase as the bed resistance of the river increases due to the build-up of particles removed from the water being drawn to the well.
Monitoring wells will also be placed along several radial lines from the well leading in a direction opposite the river. Depending on the hydrologic conditions, these wells may represent upgradient wells. The purpose of these wells is to evaluate the contribution of groundwater to the discharge from the well. These wells will provide potentiometric water levels and water quality sampling points. The information will be used to estimate the groundwater flow to the well, and to characterize the quality of the groundwater. The study will provide a basis for establishing minimum distance guidelines for river bank filtration wells.
Task 3: Aquifer Characterization and Computer Modeling.
A suite of pumping tests will be performed on the pumping well. These will include a step-drawdown test to evaluate the well losses, a long term pumping test, and a recovery test. Water level elevations will be monitored in selected monitoring wells for inclusion in the tests analyses. The pumping test analyses will result in the evaluation of aquifer property characteristics, which in turn will be used in a computer model to estimate the zone of contribution, groundwater velocities, and flow paths. The data gathered during the operation of the river bank filter well will be used to refine and calibrate the model. The model will provide a prediction tool for examining variations in operating conditions.
Task 4: Evaluation of Operating Characteristics of the Slow Sand Filter
The operation of the slow sand filter will be monitored as to the hydraulics,
water quality, energy consumption, and operation costs. This task will
entail the installation of pressure transducers and sampling points within
the slow sand filter itself. The instrumentation will be designed to evaluate
the hydraulics of the sand filter, the head loss across the schmutzedecke,
and the seepage velocities. Sampling points installed within the filter
at various depths will evaluate the particulate and organic precursor removal
efficacy as a function of depth, or flow path distance within the filter.
Potentiometric head data at various points within the filter will be used
to compute the seepage velocities within the filter, to establish an estimate
of the contact time and depth relationship over the time of operation.
Water quality samples will be taken at preselected depths within the
filter at regular intervals during an operation cycle. These samples will
be analyzed for TOC, THMFP, color, TSS, turbidity, particles counts, UV
absorbance, dissolved oxygen, pH, temperature, and coliform bacteria. The
results obtained from the analyses of the data collected from this task
will be compared to the results of monitoring from the river bank filtration
unit.
Task 5: Comparative Operation Monitoring of the Two Systems
Both systems will be operated and monitored over a complete annual cycle. This will allow the performance of both systems to be compared for the typical seasonal variation in operating and water quality conditions. The operating conditions will be monitored using pressure transducers and sampling points described in the previous tasks. Power consumption will be monitored with separate power meters for each system. Maintenance operations will also be noted, along with tracking of the raw materials needed for filter cleaning operations in the case of the slow sand filter. In a comparison of the two systems, the schmutzedecke build-up of the slow sand filter is likened to the riverbed sediment of the river bank filtration system. The schmutzedecke of the slow sand filter will be monitored by periodic core sampling of the slow sand filter surface, and hydraulic head measurements at piezometer points installed in the sand filter. The river bed material will also be periodically sampled at times similar to the slow sand filter, to evaluate the build-up of particulate matter across the contributing riverbed area. In addition to regular sampling, the riverbed material will also be sampled following significant rainfall-runoff events, to evaluate the riverbed scour and natural "filter cleaning" which occurs with the river bank filtration system. Changes in the hydraulic conductivity of the bed material will be evaluated by monitoring piezometers installed at incremental depths within the river bed over time, and using seepage meters to measure the infiltration rate through the river bed sediments. Water quality samples will also be taken at regular intervals from sampling points at incremental depths below the river bed, to monitor changes in removal efficacy.
Changes in the nature of the riverbed sediments will be monitored by examining the sediment cores taken from the river for depth, hydraulic conductivity, grain size distribution and organic content. In addition to the changes in the riverbed sediments, changes in the area of contribution will be monitored by examining changes in the piezometric levels of the monitoring well network, and also the water quality of the well discharge. Differences in the water quality of the discharge, especially in those characteristics indigenous to groundwater, may indicate a change in the proportion of groundwater to surface water making up the water produced from the well, due in part to changes in the riverbed resistance.
3. Dam Analyses and Comparisons
The data collected during the Task 5 monitoring and sampling activities
wilt be entered into a relational database, such as MicrosoftTM ACCESS.
The piezometric head data of the monitoring wells will be used to evaluate
the area of contribution, and the flow lines to the well. This data will
also be used to calibrate the computer model. The model will provide a
tool for predicting and evaluating the zone of contribution from the river,
and also the relative percentage of groundwater being drawn into the well.
The riverbed sediment information will be used to evaluate the adequacy
of natural scour processes for "cleaning" the river bank filter system.
The operation data for both processes will be analyzed to evaluate
the time relation of the filter media resistance for both technologies,
the time relation of the contributing infiltration area of the river, and
also the t/me relation of the groundwater contribution to the river bank
filtration pumping well. The data will be statistically analyzed for correlations
between particulate removal efficacy and distance along the fluid flow
path for each filter. In the case of the river bank filtration system,
correlations between the particulate removal efficacy and the fluid velocity
will also be investigated.
An overall comparison between the methods will be made, in particular with respect to the particulate removal efficacy, and operating costs. At a minimum, recommendations will be made as to the minimum distance from the river for the pumping well. Recommendations may also be made as to the acceptable range of seepage velocities for the river bank filtration system.
The project investigators for this program will be Dr. Larry Brannaka and Dr. Robin Collins from UNH. The proposed budget for this 24 month study is $142,433.
III. Innovative Comparisons of Treatment Program. The preferred approach to selecting the optimum water treatment technology for a given source water is to make side-by-side comparisons using pilot evaluations of the treatment candidates. These on-site studies greatly reduce confounding influences induced by raw water quality variations and will make treatment technologies comparison more meaningful and equitable. In many instances, comparable treatment processes may also be combined to produce a more innovative and effective treatment scheme. For example, ozone and activated carbon absorption may be combined effectively into biological activated carbon filtration (BAC).
The major goal of this initial program will be to explore the efficacy of combining microfiltration (MF) and LTV light irradiation for the development of a multi-layer disinfection unit. Microfiltration is an effective barrier for larger-sized pathogenic microorganisms such as Giardia cysts and Cryptosporidium occysts but has received mixed reviews for the removal of bacteria and especially viruses. However, tighter membranes such as ultrafiltration and nanofiltration can effectively removal bacteria and viruses but at the expense of lower membrane flux and higher operating costs.
Disinfection using UV light has been shown to be effective against viruses, bacteria and, at higher lamp pressures, may inactivate Cryptosporidium oocysts. However, higher lamp pressures may accelerate quartz fouling and significantly increase operating costs. Combining both MF with lower pressure UV disinfection will maximize the strengths of each technology while minimizing each processes weaknesses.
The project will involve the development of a unit treatment process that couples a pressurized membrane filter followed directly by UV irradiation equipment. Both treatment technologies will necessitate working closely with a membrane manufacturer (Pall Corporation - Port Washington, NY) and a UV equipment manufacturer (Trojan Technologies). A local surface water will be used for the pilot study. Treatment evaluations will be made first on the individual unit processes and then on the combined unit. Performance will be assessed by microorganism reductions as quantified by coliform bacteria and bacillus spores. Challenge runs of Giardia cysts, Cryptosporidium oocysts, and MS2 bacteriophage will also be conducted under controlled conditions. Operation and maintenance issues will be compared between the individual units and the combined treatment unit.
LTV inactivation of bacteriophage MS-2 and Adenovirus (Serotypes 40
and 41) will be emphasized. MS-2 in other studies has been shown to be
more resistant to UV inactivation then other single stranded RNA enteroviruses,
such as Poliovirus and Hepatitis A virus, so MS-2 can be used as a surrogate
for these viruses. Adenovirus, and to a lesser degree, the human strain
of Rotavirus, have been shown to be more resistant to UV inactivation than
MS-2. Because Adenovirus appears to be more resistant to UV inactivation
than Rotavirus, it is not necessary to evaluate both viruses, evaluation
of Adenovirus should be sufficient and is within the budgetary scope of
this proposal. An additional reason for evaluating Adenovirus is because
this virus is on the EPA's Candidate Contaminate List (CCL) for viruses
in drinking water, and hence, data concerning the UV inactivation of this
virus is of most importance to them.
The project investigators for this program will be Dr. Jim Malley,
Dr. Robin Collins and Dr. Aaron Margolin from UNH. The proposed budget
for this 24 month study is $127,869.
IV. Costing Summaries of New Water Treatment Technology Program. In many instances, water treatment costs are the most important factor in the selection process. Both construction and operation and maintenance (O&M) costs must be taken into account. Recent treatment technology process selections by New England communities emphasized the importance of O&M costs. Unfortunately, cost summaries of newer treatment technologies are not readily available to the community decision-makers or to the engineering consultants.
The major goal of this program is to develop both construction and O&M cost summaries for at least 2-3 water treatment technologies recently developed or used by small systems. Emphasis will be given to costing summaries germane to the New England region but also collecting data nation-wide where applicable. A unique opportunity is present in northern New England with the recent construction of 20 new slow sand filtration facilities in the past 10 years and 4-5 ceramic media pressure filtration plants constructed in the last 5-6 years to develop up-to-date cost summaries for two "new" filtration technologies.
The principal investigator for this program is Dr. Robin Collins with major contributions from Dr. Jim Malley. The estimated budget for this 18 month program is $56,291.
The New England Regional Small Public Water Supply Technology Assistance Center (SPWSTAC) at the University of New Hampshire, with input from the Regional Advisory Board, will focus on four major programs including (i) a technical training resource center for regulatory and consulting engineers who are involved with small drinking water systems, (ii) a nationally-focused evaluation program of unaligned treatment technologies, (iii) a nationally-focused innovative technology comparison program, and (iv) a treatment technology cost summary center.
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