plant data collection task group municipal wastewater … quality and... · 2012. 11. 30. · case...

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Plant Data Collection Task Group (Municipal Wastewater Treatment Design Committee - Knowledge Management Subcommittee)

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WEF Webcast SeriesData Quality and Validation

Introduction Objectives

Overview of webcasts

John Bratby, Brown and Caldwell

Objectives

Plant Data Collection Task Group (Municipal Wastewater Treatment Design Committee - Knowledge Management Subcommittee)Promote sound data for planning

purposesParticularly those with upcoming or stricter

nutrient regulations

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Overview

First webinar:Characterization of sampling locations –

“plant sampling survey” (Stephanie Fevig)

Sample handling techniques (Derya Dursun)

On-line instrumentation (Leiv Rieger)

Data compilation (Derya Dursun and John Bratby)

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Overview

Second webinar (January 9, 2013):Interactive workbook: “how much

sampling is enough”Case studies on sample handling

techniquesData storage and acquisitionMethods to identify data reliability

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Cost impacts of operating data

Information from a number of WWTPs:Approximately 10% of WWTP O&M

budgetIncludes sample collection, metering, process

control systems, processing, SCADA entry

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Use Existing Work as Baseline

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Evaluating the reliability of data

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Data verification– Identify anomalies in data reporting and analytical

procedures• Identify outliers by parameter ratios and statistical deviations

– Identify anomalies in sampling procedures• Carry out isolated mass balances to compare different sets of

data

References:Rieger L. et al. (2010) Water Env. Res., 82, 6.Bratby J. et al. (2011) WEFTEC Proceedings,

Data Storage and Acquisition

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Manual (Operator)

Data

Lab Data

Data acquisition; Reports; Charts; etc.

Control System

Data

Historian (PI)

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Sampling workbook to guide Utilities

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Routine sampling for process control and planning

Permit requirements will likely require additional analyses and frequencies

A series of questionnaires in interrelated spreadsheet tabs:

Overview of questionnaires

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John BratbyPh.D., P.E.

Brown and CaldwellGolden, Colorado

Email: [email protected]

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Presenter contact information

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The importance of characterization

of sample locations

Stephanie FEVIG, Brown and Caldwell

Introduction

• Background

• Purpose and Need

• Benefits

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Characterization of Sampling Locations• Sampling Record

• Examples

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Importance of a Sampling Record• Collection Inventory

• Consistency

• Better precision

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What to Record

• Location

• Type

• Parameters

• Frequency

• Special practices

• Responsibilities

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Location: Headworks(2/3)

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Description: Primary Influent

Sample Type: Auto 24-hr composite, flow proportioned

Details Available of Sampling Location: After grit basins in channel before flume. Equal influent flow split to 2 flumes. Only one of two channels sampled. North channel sampled at this time. Longer hose installed for sampling South channel if North channel off line.

Sampling Frequency: Midnight to Midnight

If used, type of on-line instrument:

Constituents Measured:BOD, cBOD, COD (W-Fri), NH3, TSS, Cl, conductivity

Notes:Centrate added just upstream in manhole (therefore, influent samples contain centratereturn). Strainer on end of hose approx. 6 to 9-inches below water surface. Tubing cleaned monthly.

Tubing from sampler

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Location: Aeration Basins

Description: PE

Sample Type: A/B

Details Available of Sampling Location:

Deck of AB influent channel (= primary effluent channel). Vertical sample tubing about 10 feet from deck.

Sampling Frequency:

Midnight to Midnight


Constituents Measured:

NH3, TSS, cBOD, VFAs

Notes:

Monthly bleach soaking/cleaning of hose

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Location: Aeration Basins Description: Mixed Liquor

Sample Type: Grab

Details Available of Sampling Location: Sample taken at end of each basin. Dip sample taken at gate as mixed liquor flows over into channel.

Sampling Frequency:Twice per day


Constituents Measured:Temp, MLSS, SVI (only final pass), OUR

Notes:

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Location: Blower Building

Description: PS (primary sludge)

Sample Type: Manual composite

Details Available of Sampling Location: PS Pump discharge. Operator turns on pump, waits approx. 30 seconds and takes a sample. Sample taken to lab.

Sampling Frequency:

2 times per day


Constituents Measured:

TS, VS

Notes:

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Location: Dewatering

Description: Centrifuge cake

Sample Type: Grab

Details Available of Sampling Location: Sample from chute

Sampling Frequency: Twice per run


Constituents Measured: TS, Temp, pH, volatiles

Notes:

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Stephanie FevigP.E.

Brown and Caldwell



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Importance of Sample Handling Techniques when Carrying Out In

Basin Data Collection- A Case Study

Derya Dursun

Brown and Caldwell,

BACKGROUND

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Involves FIVE main steps1. Obtaining the sample from the bulk system2. Prepare the sample for analytical analysis3. Execute the method chosen for the analysis4. Manage the data5. Calculations and report the results

Step 3 most extensively examined

Strategy for Successful Results

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SAMPLE HANDLING

If not sampled and/or prepared properly, then

testing is useless!!!!

Sample handling between sampling site and laboratory is

critically important and crucial to the success of an analysis

Importance of Sample Handling

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Main GoalSample’s integrity must be strictly maintained

and preserved

1. Addition of a preservative (if needed-when)2. Accurate documentation

Sample Handling

DO’s

• Keep the sample in its original

physical/chemical condition• Remains representative of the

bulk system• Analyte identity and concentration

• Use clean containers or

laboratory equipments

• Store the samples at

appropriate temperature

Maintaining Sample Integrity

DON’T’s• Lose sample matrix or solvent

through evaporation or other means (spills etc)

• Lose analyte through evaporation, chemical reaction, temperature effects, bacterial effects, etc.

• Contaminate with additional analyte through erroneous contact.

• Moisture absorption or adsorption by exposure to humid air

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Maintaining Sample Integrity

Will be specific to the analyte– Adding a preservative– Maintaining specific conditions of

temperature/humidity, etc.– Avoiding sunlight or oxygen– Equipment should be clean and free of

material that would remove analyte or add contaminant

• Chain of Custody = Document handling of the sample

• Chain of Custody includes;– Who did the sampling

and preparation– How sample collected– Where collected from– Provides continued and

detailed documentation!

Documentation Client NameProject NameContact Information

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CASE STUDY In-basin profiles of nitrification and

denitrification

This sampling plan involved profiling DO, NH3, NO3 and NO2 on a dynamic basis to verify nitrification and denitrification parameters

Special Sampling Plan

MONITOR: Primary Effluent Flow, COD, TKN, NH3, pH, Alkalinity

MLVSS profile in aeration basins

MLSS profile in aeration basins

ML Temp profile in aeration basins

DO profile in aeration basins

NO3, NO2, NH3 profiles in aeration basins

Secondary Effluent NO3, NO2, NH3 and TKN, fTKN, ffTKN

RAS Flow, RAS solids concentration

IMLR Flow

Create the Sampling Plan with Awareness

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In-Basin Parameters to be Analyzed

DO,pH and Temperature measured onsite with a calibratedhand-held probe

AB-1

AerobicAB-2b

Aerobic

AB-2a

Anoxic

AB-3

Aerobic

AB-4

Aerobic

DO, NH3, NO3, NO2, TSS, VSS,

Temp.RAS

PE

SE

NH3, TKN, NO3,NO2, ffTKN, fTKN

Flow, COD, TKN, NH3, pH, Alkalinity


Temp.


Temp.

Mixed Liquor Samples were taken from Aeration Basin to analyze;

TSS, VSS, NH3, NO2, NO3

Mixed Liquor Samples

• Soluble species (NH3, NO3, NO2) continue to be converted in mixed liquor after sampling

• Biological reactions must be arrested the moment when samples are taken

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Mixed Liquor Filtration is key

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Immediate filtration is a key component to accurately determine soluble species

1. Use a coffee filter on-site and then transfer the preliminarily filtered samples to the laboratory

2. Use directly in-situ with 1.2µm syringe filters

OR

Notes on Filter Selection

Filters with 25 mm diameter are recommended to allow membrane filtration of raw wastewater

Membrane filters with pore size of 1.2µm are suitable (such as Whatman GD/X – these filters have a coarse layer, followed by a finer layer, ending with a membrane)

Be sure to rinse the filter with distilled water before filtering the sample

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Preserving Mixed Liquor Samples

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Samples should not be preserved before filtration

Preservation, apart from cold storage, should only occur afterfiltration

Primary & Secondary Effluent Samples

• Flow

• pH

• Alkalinity

• COD

• TKN

• NH3

Parameters measured in Primary Effluent

Parameters measured in Secondary Effluent

• TKN

• NH3

• NO3

• NO2

• filtered TKN

• floc filtered TKN

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Secondary Effluent Nitrogen SpeciesNitrogen species in wastewater are transformed in wastewater treatment facilities resulting in effluent N

species with different chemical composition than those found in the influent wastewater

Most of the N species including NO3, NH4, and particulate N can be efficiently removed from wastewater, however, the

same is not true for Dissolved Organic Nitrogen and Colloidal Organic Nitrogen.

Conventionally, filtration method (0.45 um pore-size filter) is used to measure soluble constituents. However, the filtrate pore-size filter contains colloidal fractions. In order to remove colloidal fractions flocculation filtration

method can be used

The Floc-Filtration TechniqueAlum (Al2(SO4)3.16H20) or Zinc Sulfate can be used

Secondary Effluent + alum

2 min rapid mixing 15 min slow mixing 15 min settling Filter from Whatman GF/C

• Flocculation step must be conducted immediately after sampling

• Filtration step has to follow the flocculation

• Preservatives must be added to filtered samples

• Proper storage conditions must be used

• Samples have to be labeled and chain of custody forms must be filled

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• Although the samples can be sent to an outside laboratory for the analysis, significant amount of work still has to be done on-site

• Blending of influent or primary effluent samples is important for parameters other than suspended solids

• Immediate filtration is key for mixed liquor profiles

• Samples must be preserved after filtration

Lessons Learned/Conclusions

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Derya DursunPh.D., P.E.

Brown and CaldwellMaitland, Florida


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The importance of on‐line instrumentation What it can accomplish

How does it influence plant sampling regimes

Leiv RIEGER, inCTRL Solutions Inc., Canada

Overview

ContextInstallationCalibrationQuality controlConclusions

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Mass balances based on grab samples

Influent and process variationsContext

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Typical plant sampling timeT

SS

[g/L

]

0

1

2

3

4

5

6

7

0 4 8 12 16 20 24

Reference measurements with in-situ sensor

Resulting error +10%Time [h]

Additional calibration experiments

Context

Shift from not enough databut with typically sufficient accuracy

to

Data graveyards withoften unknown accuracy

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DefinitionsContext

Off-line On-line

In-situ

Filtrationin bypass

Ex-situ

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Ex-situ analyzersContext

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Filtration unitsContext

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In-situ analyzersContext

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• Main cost factor is due to maintenance and QA(personnel as well as chemicals and spare parts)

• Effort approximately 0.5-1 h/week per sensor

• Ex-situ systems typically more expensive(analyzer, filtration unit, housing, chemicals…)

Sensor costsContext

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AccuracyContext

• Laboratory:Established Standard Operation Procedures (SOP)

• Ex-situ analyzer:Typically “auto-calibration” routines

• In-situ sensors:Need to be monitored

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Installation

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Probe or sampling point location• Homogeneity• Representative• Sampling point always submerged• Distance to analyzer or control box• Avoid disturbances• …

Control box/analyzer placement• Housing for analyzer• Sun cover • Heating• Power/signal connection/other connections• …

Where?Installation

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Mounting of TSS probe© Tracy Doane-WeidemanEndress+Hauser

How? – In-situ sensor installationInstallation

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• Filtration unit selection• Pump selection (robustness, flow rate, cutting knifes,…)• Hose installation• Heating/cooling of hoses and analyzer location

• Allow for easy maintenance• Sampling for reference measurements ?

General

© Bob DabkowskiHACH

How?Installation

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Ex-situ analyzer installation

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Calibration

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Compare apples with apples• Homogeneity (sensor sees the same sample as lab)

• Same compound measured (e.g. NHx-N vs. NH4-N)

What is the reference method ?• More accurate than sensor method• Possible to be carried out at plant lab or by plant staff

How to calibrate your sensor?• With standards ?• With reference measurements ?• In process or in bucket ?

GeneralCalibration

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• Bucket calibration guarantees homogeneity for sensor andreference measurement

• However, difference between in-situ and bucket conditions !

Beaupré, 2010

In-situ or bucket calibration?Calibration

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Example: TSS sensor in aeration tankCalibration

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Example: TSS sensor in aeration tankCalibration

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What about lab accuracy ?

What is the reference method ?• More accurate than sensor method• Possible to be carried out at plant lab or by plant staff

How to calibrate your sensor?• With standards ?• With reference measurements• In process or in bucket ?

• Calibrate for what range ?

• Sensor response time ?

GeneralCalibration

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Working range

Measuring range

Working range

Working range / Measuring rangeCalibration

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Ex-situ analyzer NH4-N

T90 = 30 Min.

In-situ sensor DO T90 = 1.1 Min.

Rieger et al., 2003

Response timeCalibration

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Quality control

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What accuracy can the sensor deliver ?

What is required for your control system ?

How fast do you need a measurement ?

What is a good measurement?Quality control

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Monitoring Calibration≠

Quality control

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Measurements x

Number of measurements1 2 3 n Probability density

function f(x)

Outlier

Random measuring errors(Precision) 95%

Confidence intervalSystematicmeasuring errors(Trueness)

xtruextrue

Prevent systematic measuring errors

Quantify random errors

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Types of errors (symptomatic)Quality control

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Reference measurement

Mea

surin

g si

gnal

Calibration

TimeRes

idua

ls

Quality control

Concentration range ?Time ?

Systematic errorsQuality control

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Manual cleaningSensor1 (Control of blower, without cleaning)Sensor2 with autom. cleaningSensor3 with autom. cleaning and calibration

Careful with controlled variables

© Stefan WinklerTU Vienna

DO sensorsQuality control

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© IMW Final Report (2005)

Auto-cleaningQuality control

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Conclusions

On-line instruments:Need a clear scopeRequire attention and trained operatorsDon’t save money per seProper installation and calibration is keyData quality monitoring ≠ calibration

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Is this theright installation?

© Bob DabkowskiHACH

Best of … collection

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Leiv RiegerPh.D., P.Eng.

inCTRL Solutions Inc.Canada


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The importance of good data compilation and organization; examples of outlier

identification and data trending

John BratbyDerya Dursun

Data collection and data analysis used for plant control is evidence of good

engineering

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How to Make Use of Data

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Data Information Knowledge Understanding

Numbers, Values

Numbers, Values

Daily Influent BOD

Concentration

Daily Influent BOD

Concentration

WWTP has high influent BOD values

WWTP has high influent BOD values

Industrial influent coming into the

WWTP has increased the influent BOD

Industrial influent coming into the

WWTP has increased the influent BOD

• Data production at treatment facilities increased significantly as the technology and the tools used in the facilities has enhanced

• With automated controls, it is possible to monitor the facility 7/24 and achieve data for very short time intervals

• Cost of developing this data is considerable – approximately 10% of the plant O&M budget

Technology and Data Flood

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Make full use of the data

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Calculate key ratios and check against typical ranges Data screened for outliers Conduct mass balances around key unit

processes (will be covered in detail during the second webinar)

Review the data using a number of “engineering” checks

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1. Develop compiled data sheet

2. Generate time series plots, include tolerance bands

3. Calculate ratios of various parameters calculated and plot as time series

4. BOD and solids loading rates generated for various streams around the plant

5. Solids mass balances calculated around various unit operations overall sludge production checked (next webinar)

Historical Data Review – Approach

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– Consolidating all data into a centralized file-database (generally received in monthly reports)

– Organization of data into groups, subgroups

Developing Compiled Data Files

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Some issues with data sets

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1. Changes in data layout / data types 2. Changes in scale / format 3. Missing and default values 4. Gaps in time series

Often, the analysis of several years of plant data requires the retrieval of monthly reports and

compiling these separate files into one usable database.

There are difficulties with this, all contributing to errors, and costs:

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Most of the data we obtain from the WWTP’s are in Time Series and Quantitative (numerical)

Generating Plots

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Raw data can be very messy!!!

• Apply some basic statistics to determine the data distribution (calculate average, min, max, median, standard deviation etc)

• Plot tolerance bands into time series

Including Statistical Analysis

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Daily cBOD5 Concentration

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Check ratios for historical data against typical ranges

Calculating Ratios

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An example time series for TSS/cBOD ratio

Ratio Plots

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Daily TSS/cBOD5 RatioOutlier?

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Identification of Outliers

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• Removal of Gross Errors (such as measurement errors, sCOD is higher than tCOD)

• Evaluation of time series plots, statistics • Assessment of time series plots for ratios. This is

the easiest way to detect trends, drifts, shifts, outliers and also special events

• Comparison of the values with literature values• Comparison of values with the values for the same

kind of other plants

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CASE STUDY

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An Example of Data Mining Using the Compiled Spreadsheet

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Compile the data as a continuous dataset

The test selected here for outliers is greater than or less than 2.5xstandard deviations around the average


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With conditional formatting, highlight the ratios that are greater than the overall average + 2.5xStandard Deviation (red) andless than the overall average -2.5xStandard Deviation (yellow)

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Here, ammonia could be too low. However, since the value still appears to be reasonable compared with other ammonia values before and after this date, the data point not eliminated in this case.


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Here, the TSS value appears to be too high, based on the other ratios. In this case the TSS value of 320.9 is deleted.

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1

Here, BOD appears too low, based on a comparison with the other ratios. Therefore, the BOD value of 140.4 is deleted.

• Conduct mass balances around key unit processes

• This will be covered in detail during the second webinar

Complete Checks on Plant Data with a Series of Mass Balances

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Additional Checks on Plant Data with a Series of Mass Balances

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Example 1: Primary Clarifiers

Additional Checks on Plant Data with a Series of Mass Balances

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Example 2: Activated Sludge

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John BratbyPh.D., P.E.

Brown and CaldwellGolden, Colorado


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Presenters contact information

Derya DursunPh.D., P.E.

Brown and CaldwellMaitland, Florida


Questions?

plant data collection task group municipal wastewater … quality and... · 2012. 11. 30. · case...

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