14 aug 2003 Metering Brazil’03 1 Metering, Billing, CRM/CIS Americas 2003 Medição, Faturamento, CRM/CIS Brasil 2003 12-14 August 2003 Crowne Plaza Hotel, Sao Paulo, Brazil Indirect sewage billing, by water consumption balance and telemetry Jorge Gomez Sanchez Engineering & Systems Invensys Metering do Brasil
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14 aug 2003 Metering Brazil’03 1
Metering, Billing, CRM/CIS Americas 2003 Medição, Faturamento, CRM/CIS Brasil 2003
12-14 August 2003Crowne Plaza Hotel, Sao Paulo, Brazil
Indirect sewage billing, by water consumption balance and
telemetry
Jorge Gomez SanchezEngineering & Systems
Invensys Metering do Brasil
14 aug 2003 Metering Brazil’03 2
Sewage billing In Brazil, Sanitary companies are usually
responsible for water distribution and sewage collection services
In water supply the water consumption is billed by the volume read on watermeters
The sewage is much more difficult to be billed : There is no characterised “product” to base the bill It is not easy to measure the discharged volume and
flowrate It is not easy establish the “cost” of the discharged sewage
Sewage billing is a potencial source of controversy with consumers
14 aug 2003 Metering Brazil’03 3
Sewage billing
Ways to refer and establish the sewage bill :
Charge a fixed fee, according to consumer categories (industrial, residential, commercial)
Industrial billing based in categories related to parameters, like size, kind of activity and product, level of production
Sewage bill based only on water consumption
Sewage bill based on the water consumption together to other parameters related to pollution burden
Bill based on direct sewage measurement
14 aug 2003 Metering Brazil’03 4
Billing by fixed fee, based or not on external parameters
AdvantagesEasy billing and
controlDoes not rely on
meters and periodic reading
No inspection or checking is necessary
ProblemsInduce consumer complain
(even who does not produce sewage pays the same fee)
Does not identify consumers that overcharge the system
Does not incentive rationalisation of resources
The tariff is the same, independent on discharged sewage
Adequate to places with low variability
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Sewage bill based only on water consuption
AdvantagesFair: Usually, the higher is
the water consumption, the higher is the sewage discharge
It is easier to express the sewage bill together with the water bill
Industries, that usually charges more the systems, pay higher tariff
Problemshigh water consumption not
always means high generation of sewage
The proportion water /sewage can be questioned
The consumer fells that the water is expensive: It tents to use alternatives suppliers.
Alternative water suppliers, like wells and rain collectors, have to be metered as well
It is a good alternative to charge fixed fees, but the consumer sometimes does not agree and goes to judicial claim
14 aug 2003 Metering Brazil’03 6
Bill is proportional to water consumption and other fixed
parameters Discounts can be applied in order to not
characterise that water consumption = sewage discharge
Multipliers can be applied according to the potential pollution burden examples :leather and food industries
multipliers and discount parameters can be established with water consumption and sewage surveys
14 aug 2003 Metering Brazil’03 7
Bill proportional to water consumption and fixed
parameters water comsumption parametrization Example: generic industry
Water inlet (watermeter)
Sewage outlet
factory
Office
Colling towers Steam generator
(boiler)Incorporated
water processesrefectory
Gardens (irrigation)
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Bill proportional to water consumption and fixed
parametersAdvantages
Survey allows sewage characterization and makes the bill clear Identify the sewage generators: incentive to conservation actions Incentive sewage treatment by the consumerIdentify alternative water supply
problemsSurvey takes an instant
“picture” but the parameters can change
The consumer know when the survey is carried on na can change the activity
The sewage emission sometimes is not proportional to the water consumption
The survey is expensive and sometimes difficult
This method is been used by consumer demand, that hire consultant companies to do the surveys.
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Direct measurement of sewage volume
Consists in install a meter in the sewage outlet of the consumer, in order to have the actual sewage volume that is discharged
Metering technologies that is been developed to measure sewage flowrate: Eletromagnetic Ultrasonic Open chanel Ultrasonic meters Weirs and flumes
Direct measurement of sewage volume is a frequent consumer demand
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Direct measurement of sewage volume
AdvantagesDirect metering is clear for the consumer
Does not depends on water consumption surveys
Makes the water consumption and the sewage bill separate : The consumers really perceive the cost of the water and the sewage
ProblemsThere is no meters accepted by Brazilian metrological authority (INMETRO)
Sewage is not a well defined fluid: the measurement carries high uncertainty
It is not possible to be sure that the measured outlet is the only one.
The meters frequently over range when it rains (weirs overflow)
The consumer can concentrate the sewage (reduce the flow but not the pollution burden)
Direct measurement is not yet a reliable technology to be used as a reference for sewage billing
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A proposal: simultaneous measurement of the consumed water that is not discharged
as sewage Instead of estimate the sewage by the
volume of consumed water, it is measured the amount of water that goes to processes that does not produce sewage : Water consumed in steam generation Water consumed in cooling tower (air conditioned) Water that is incorporated to the product (ex.
Beverage industries, concrete pre manufactured) The water bill is still based on the main
meter, but the sewage bill is based on the difference between the main meter and the process meters
14 aug 2003 Metering Brazil’03 12
Measuring the consumed water that does not generate sewage
Generic industry
m
m
m
Water inlet (watermeter)
Sewage outlet
factory
Office
Colling towers Steam generator
(boiler)
Incorporated water processes
refectory
Gardens (irrigation)
m
14 aug 2003 Metering Brazil’03 13
Measuring the consumed water that does not generate sewage
Advantages The process is directly metered: There is not a fixed
relationship between sewage and consumed water There is no problem in previsions of season variation and
change in production Is the consumer that declares the process that consume
water but not discharge sewage: No judicial claims . Use of alternative sources can be verified on the balance Does not incentive sewer by passes or sewage
concentration Common water meters, certified by INMETRO, can be used Parameter surveys are not necessary The direct metering can be accessed by the consumer, that
knows the billing process, and can work to reduce it
14 aug 2003 Metering Brazil’03 14
Measuring the consumed water that does not generate sewage
Problems
Sometimes the meters have to be installed in places with not easy access for maintenance and reading
It is possible to get water from the process after the process meters
Eventual inconsistencies due to broken meters or variations in the activities can be noticed just after some readings (months)
It is still necessary to evaluate the consumer process to confirm the processes that consumes water but not discharge sewage
14 aug 2003 Metering Brazil’03 15
Measuring the consumed water that does not generate sewage
water use balance by on line reading and telemetry
Central metering (meter + telemetry) Sewage
outlet
Factory
Offices
Cooling towers Steam generator
(boiler)Incorporated water
process
refectory
Gardens (irrigation)
m
m
m
m
CM
Parcial meter
Parcial meterParcial meter
Parcial meter
Comunication lines
14 aug 2003 Metering Brazil’03 16
Measuring the consumed water that does not generate sewage
water use balance by on line reading and telemetry
All the meters are read simultaneously by telemetry
The reading of the partial meters is transmitted by wires or radio to a metering centre, that processes the readings and presents partial readings and the water consumption and sewage volume to be billed.
The metering centre can be directly connected to the utility by phone, mobile phone (GSM) radio on even optical cable (cable TV)
14 aug 2003 Metering Brazil’03 17
Measuring the consumed water that does not generate sewage
water use balance by on line reading and telemetry
Examples:
Discount of water consumption on cooling towers Commercial offices with central air conditioning Shopping centres Industries with large heat exchanges
Companies that uses steam intensively Commercial and industrial consumers with
large loans and irrigated gardens
14 aug 2003 Metering Brazil’03 18
Added featuresWaste and pollution burden control
Other measurement devices can be connected on line to the system: Mesurement of sewage characteristics: temperature,
pressure, PH, conductivity, composition na even flow rate.
Other meters can be added to the system to be used as conservation feed back and management of the resources
The readings and evaluation can be available to the consumer by Internet
14 aug 2003 Metering Brazil’03 19
Detailing the system telemetry with communication on line
System architetureCommunication
media MBUSTelemetry
centre
Main meter
Partial meters
...
Net up to 250 meters, 4 km
wire
Pair of wiresM-Bus
A/D converter (Mbus)
Sewage meter (Weir)Pressure sensor
Other devices
-temperature
-PH
-composition
14 aug 2003 Metering Brazil’03 20
Detailing the system telemetry with communication on line
Metering centre
14 aug 2003 Metering Brazil’03 21
Detailing the system telemetry with communication on line
Metering centre
14 aug 2003 Metering Brazil’03 22
Detailing the system telemetry with communication on line
Metering centre
14 aug 2003 Metering Brazil’03 23
Evaluation software
14 aug 2003 Metering Brazil’03 24
Detailing the systemencoded meters and Intelligent pulser (HRI)
14 aug 2003 Metering Brazil’03 25
Conclusions The preset proposal of sewage billing based on water
consumption balance is closer to reality than other ways of billing, reduces consumer complains and the perception of high water price
Use of telemetry and evaluation software allows a better use of water, leak detection and identification of irregular water sources or even changes in consumer characteristics m
The system is available and is in use by SABESP The cost of the system can be partially supported by the
consumer, that has real interested in be billed by real sewage volume and not by the water consumption
14 aug 2003 Metering Brazil’03 26
Invensys: Technology for an intelligent world
Invensys Metering do BrasilJorge Gomez Sanchez - Engenharia & sistemas