Characteristics of Urban Wastewater
According to Tchobanoglous et al 2003, urban wastewater components may vary depending on type of collection system and may include:
1 Domestic (sanitary) wastewater Wastewater discharged from residential areas, and from commercial, institutional and similar facilities
2 Industrial wastewater Wastewater in which industrial wastes predominate
3 Stormwater Runoff resulting from rainfall
4 Infiltration/Inflow Water that enters the collection system through indirect and direct means Infiltration is extraneous water that enters the collection system through leaking joints, cracks and breaks, or porous walls Inflow is stormwater that enters the collection system from storm drain connections, roof leaders, foundation and basement drains, or through access port (manhole) covers
The constituents of wastewater can be classified as physical, chemical and biological
The primary concerns in wastewater treatment are suspended solids, biodegradable organics, and pathogenic organisms, as highlighted in Table 1.1 Wastewater treatment facilities are specifically engineered to effectively eliminate these constituents to ensure water quality and safety.
Wastewater contains various types of solids, ranging from coarse to colloidal Prior to analyzing these solids, it is essential to remove the coarse materials In wastewater treatment, solids are classified based on size and state (suspended and dissolved solids), chemical characteristics (volatile and fixed solids), and settleability (settable and non-settable suspended solids) (Sperling, 2007).
Table 1.1 Principal constituents of concern in wastewater treatment a
Total suspended solids Sludge deposits and anaerobic conditions
Biodegradable organics Depletion of natural oxygen resources and the development of septic conditions
Dissolved inorganics (e.g total dissolved solids)
Inorganic constituents added by usage Recycling and reuse applications
Heavy metals Metallic constituents added by usage Many metals are also classified as priority pollutants
Nutrients Excessive growth of undesirable aquatic life, eutrophication, nitrate contamination of drinking water
Priority organic pollutants Suspected carcinogenicity, mutagenicity, teratogenicity, or high acute toxicity Many priority pollutants resist conventional treatment methods (known as refractory organics) a: From Crites & Tchobanoglous, 1998
Determining particle size is essential for understanding the characteristics of Total Suspended Solids (TSS) in wastewater This analysis not only provides insights into the nature of these particles but also evaluates the effectiveness of various treatment processes, including biological treatment, disinfection, and sedimentation.
Turbidity measures how well light can pass through water, serving as an indicator of water quality in both natural bodies and waste discharges, particularly concerning suspended and colloidal materials (Tchobanoglous et al., 2003).
Wastewater color arises from suspended solids, colloidal materials, and dissolved substances Apparent color refers to the hue created by suspended solids, while true color is attributed to colloidal and dissolved components.
The sources of color in wastewater include infiltration/inflow (humic substances), industrial discharges (e.g dyes or metallic compounds, etc) and the decomposition of organic compounds in wastewater
Transmittance refers to a liquid's capacity to allow light of a specific wavelength to pass through a defined depth of the solution In contrast, absorbance measures the reduction of radiant energy as light travels through a fluid (Tchobanoglous et al., 2003).
Transmittance is influenced by various factors, including specific inorganic compounds like iron and copper, organic compounds such as organic dyes and humic substances, as well as conjugated ring compounds like benzene, along with total suspended solids (TSS) (Tchobanoglous et al., 2003).
Variety of malodorous compounds released under anaerobic conditions in biological process of wastewater treatment
Hydrogen sulfide is the primary compound responsible for unpleasant odors, but under anaerobic conditions, other compounds like indole, skatole, and mercaptanes can produce even more offensive smells.
Temperature measurement is crucial in wastewater treatment facilities, as the biological processes involved are temperature-dependent Wastewater temperatures fluctuate based on seasonal and geographical factors, ranging from 7 to 18°C in colder regions and from 13 to 30°C in warmer areas.
Temperature plays a critical role in water quality, influencing chemical reactions, reaction rates, and the health of aquatic life Variations in temperature can significantly impact the survival of various fish species Moreover, elevated temperatures result in decreased levels of dissolved oxygen in water, as the increased biochemical reaction rates can lead to oxygen depletion (Tchobanoglous et al., 1998).
Density, Specific Gravity and Specific Weight
Wastewater density (ρ w) is defined as its mass per unit volume, measured in g/l or kg/m³ (SI) This parameter is crucial for designing treatment units, including sedimentation tanks and constructed wetlands.
Electrical conductivity (EC) refers to a liquid's capacity to conduct electrical current, primarily facilitated by ions present in the solution The EC measurement is essential for assessing the concentration of total dissolved solids in the liquid.
The electrical conductivity is expressed in SI units as millisiemens per meter (mS/m) 1.1.2.2 Inorganic Chemical Characteristics
Wastewater chemical constituents are categorized into inorganic and organic compounds, with a focus on inorganic elements in this section The pH value, a crucial measure of acidity and alkalinity in aqueous solutions, typically ranges from 0 to 14 at temperatures of 20°C or 25°C Defined as the negative logarithm of hydrogen-ion concentration, the pH is calculated using the formula pH = -lg [H+] Most biological life thrives within a narrow pH range of 5 to 9; deviations below 5 or above 9 hinder microbial activity essential for biological treatment Without proper pH adjustments, effluents from domestic wastewater treatment facilities can significantly alter the pH of receiving water bodies.
Nitrogen and phosphorus are crucial nutrients for biological growth, acting as biostimulants in various processes Nitrogen, a key component in protein synthesis, is essential for making wastewater treatable Wastewater contains different forms of nitrogen, including ammonia, nitrite, nitrate, and organic nitrogen, which is associated with amine groups (Sperling, 2007).
Ammonia exists in aqueous solution in two forms the ammonium ion or ammonia gas, depending on the pH of solution as the following equilibrium reaction:
At pH levels above 9.3, ammonia gas is predominant; at level below 9.3 the ammonium ion is major
Overview of the Urban Wastewater Management System
1.2.1 Components of Urban Wastewater Management System
Wastewater Management System includes three main components: (1) collection, (2) treatment and (3) disposal or reuse
Effective wastewater management begins with the collection and conveyance of wastewater from diverse sources This is achieved through sewers, which are the pipes responsible for transporting wastewater away from its origins, forming a comprehensive collection system.
(George Tchobanoglous, 1981) Most sewers are placed underground to prevent interference due to repair of this system (Punmia and Jain, 1998) The types of collection systems will be discussed later
Wastewater treatment is a crucial component of effective wastewater management systems, as it minimizes environmental pollutants and safeguards human health from pathogens (Punmia and Jain, 1998) This process involves a combination of various unit operations, employing mechanical, physical, chemical, and biological methods, as well as hybrid approaches like physiochemical methods The diversity of these treatment techniques will be explored in subsequent sections.
After treatment, water can either be disposed of or reused, with the method of disposal closely linked to the self-purification capabilities of water bodies Engineers determine the necessary degree of treatment and the type of treatment plant based on the chosen receiving water or effluent standards Treated wastewater may be released into lakes, rivers, or oceans, while its reuse can facilitate groundwater recharge and irrigation, among other applications.
1.2.2 Types of Wastewater Management System
Wastewater management systems can be classified into two main types: centralized and decentralized Centralized systems, the traditional approach, have been effectively utilized in many industrialized nations for decades, yet they pose significant investment and implementation costs for communities In contrast, decentralized wastewater systems, which treat wastewater close to its source, are gaining attention as a viable alternative to conventional centralized methods This article will explore both wastewater management systems in detail.
Figure1.1 Representation of a Centralized Wastewater Collection and Treatment System
Centralized wastewater management refers to a system that collects wastewater from households, industrial areas, small businesses, and stormwater runoff, transporting it to a treatment plant typically located outside city or village boundaries Once treated to meet regulatory standards, the wastewater is discharged into the nearest water body Additionally, the residual waste sludge, generated after pollutant removal, undergoes further treatment before any potential reuse.
Decentralized wastewater treatment systems are positioned near the original sources of waste, resulting in shorter sewer lengths for transporting wastewater These systems utilize on-site treatment plants to process both wastewater and sludge The treated effluent and sludge can then be discharged into water bodies or repurposed for applications such as irrigation and toilet flushing.
Centralized wastewater management systems have long been successful in developed countries, effectively collecting and transporting sewage and stormwater through a network of sewers These systems ensure advanced treatment and regulation before discharging treated water into natural bodies Additionally, waste sludge is properly treated, utilized, or disposed of A key advantage of centralized systems is the reliable and efficient management of treatment plants, as it is generally more cost-effective to operate one large treatment facility than multiple smaller ones within the same urban area.
Figure1.2 Representation of a Decentralized Wastewater Collection and Treatment System
Centralized wastewater systems, while beneficial, face significant limitations, primarily due to their reliance on extensive sewer networks, which incur high construction and maintenance costs For instance, a 2005 DWA survey highlighted that Germany invested approximately 1.6 billion euros to rehabilitate its 515,000 km sewer system, serving nearly 82.5 million people These systems are often over-engineered to accommodate projected population growth, resulting in excessive operational costs and inefficiencies The substantial initial investment places considerable strain on local economies Environmentally, such systems disrupt water balance by extracting water from one location and discharging treated effluent far away, complicating pollutant removal due to the varied and complex nature of combined wastewater and stormwater.
Decentralized wastewater management systems are prevalent in rural areas worldwide and offer several advantages over centralized systems These benefits include reduced construction, operation, and maintenance costs due to the absence of lift stations and storage tanks for combined sewage flow Additionally, decentralized systems enhance opportunities for water reuse and groundwater recharge, as transporting treated wastewater from centralized plants can be impractical Moreover, the failure of individual units does not compromise the entire system's functionality, and the capacity can be easily adjusted to accommodate rapid population growth.
Decentralized wastewater management systems face significant challenges, including low effluent quality that often fails to meet water reuse standards, improper operation of treatment plants, and difficulties in oversight by water authorities Current treatment methods are often outdated, relying on primitive solutions like pit latrines or low-tech options such as one to three chamber septic tanks Typically, the responsibility for the operation and maintenance of these on-site treatment facilities falls on the owners; however, most lack the necessary knowledge and motivation to ensure their systems function effectively.
Decentralized systems offer a flexible and straightforward solution for wastewater management, particularly in developing countries and certain industrialized nations However, several challenges must be addressed before these systems can be effectively implemented.
Sub-processes of Wastewater Management System
A collection system is essential in urban wastewater management, responsible for gathering wastewater from both domestic and non-domestic sources, along with stormwater, and transporting it to treatment plants This section will explore the typical components of a collection system and discuss the various types of sewers involved.
1.3.1.1 Typical Components of Collection System
An urban drainage system typically consists of building drainage, roof drainage, and main sewer networks Building drainage transports various types of wastewater to the main sewer, while roof drainage directs stormwater to the same sewer system This section will focus on the essential components or "hardware" that comprise any effective drainage system (Butler et al., 2004).
Sewers are essential components of sewerage systems that transport wastewater from various properties to treatment facilities or natural bodies of water They can be constructed from materials such as vitrified clay, concrete, or cement, depending on the specific type of sewer There are three main types of sewers: sanitary sewers, stormwater sewers, and combined sewers (Butler et al., 2004).
Manholes serve as essential access points in sewer systems for testing, inspection, and clearing blockages Typically deep enough for entry when necessary, manholes are strategically placed at key locations such as changes in direction, heads of runs, gradient shifts, size variations, and major junctions with other sewers The diameter of a manhole is determined by the sewer size and the orientation and number of inlets (Butler et al., 2004).
Gully inlets are essential for managing surface runoff as they direct water into the sewer system Each gully features a grating and an underlying sump designed to capture heavier materials from the flow Connected to the sewer through a lateral pipe, gullies include a water seal when linked to a combined sewer system The design factors, such as size, number, and spacing of gullies, play a crucial role in minimizing surface ponding during storm events Typically positioned at low points along roads, gullies are ideally spaced every 50 meters or for every 200 square meters of impervious area to ensure effective drainage (Butler et al., 2004).
Ventilation is essential in all urban drainage systems, especially in sanitary and combined sewers, to maintain aerobic conditions within the pipes and prevent the accumulation of toxic and explosive gases.
In this section, three types of sewer, including sanitary sewers, stormwater sewers and combined sewers will be introduced very briefly a/ Sanitary sewer
Sanitary sewers are designed to efficiently collect and transport wastewater from homes, institutions, and industrial areas to treatment facilities This wastewater is moved either by gravity through gravity sanitary sewers or by pressure/vacuum systems in pressure sanitary sewers.
When designing sanitary sewers, several key factors must be considered, including design flows, hydraulic design equations, and the selection of appropriate sewer pipes and materials It's essential to establish minimum and maximum velocities, as well as minimum slopes, to ensure efficient flow Additionally, alternative design options, sewer appurtenances, and proper sewer ventilation play crucial roles in the overall effectiveness of the system (Tchobanoglous, 1981).
Storm-water sewers are specifically designed to collect and manage storm water, with a key distinction being their capacity to overflow periodically For example, a storm-water sewer designed for a 10-year rainfall frequency can expect to exceed its capacity during such an event In contrast, sanitary sewers are engineered to prevent surcharges due to their higher pollutant content, with any overflow typically resulting from unexpected failures Additionally, the pipe diameter in storm-water systems is significantly larger than that of sanitary sewers, making them more resilient to excess infiltration, which can easily overwhelm the smaller sanitary systems (Hammer et al., 2008).
The design procedures for storm-water sewers closely resemble those for sanitary sewer systems, with key differences in design flow, minimum velocities, and the materials and sizes of pipes used.
A combined sewer system collects domestic and industrial wastewater along with rainwater runoff in a single pipe In dry conditions, this combined wastewater is transported to treatment plants before being released into receiving waters However, during heavy rainfall, the volume of water can exceed the capacity of the sewer network and treatment facilities, resulting in a phenomenon known as combined sewer overflow (CSO), where excess flow is directly discharged into nearby water bodies.
The primary function of a Combined Sewer Overflow (CSO) is to manage high flow rates by directing water into two separate outflows: one towards the treatment plant and the other towards receiving bodies This is typically achieved using a weir When the flow level is below the weir, all water is sent to the treatment facility; however, when it exceeds the weir, some water bypasses the treatment plant Proper hydraulic design is crucial to prevent premature overflow, which can lead to excessive pollution in water bodies, and to avoid surcharging in the sewer system Additionally, a well-designed CSO aims to minimize the discharge of fine suspended and dissolved materials, ensuring that the majority of contaminants are directed to the treatment plants (Butler et al., 2004).
The design of Combined Sewer Overflows (CSOs) is critical in combined sewer systems, with key factors including the diameter of the inflow pipe, control mechanisms for outflow, weir specifications, chamber invert levels, design return periods, top water levels, and provisions for human access (Butler et al., 2004).
Wastewater treatment typically involves several key processes, including preliminary treatment, primary settling to eliminate heavy solids and floatable materials, and secondary biological treatment to metabolize and flocculate colloidal and dissolved organics The resulting waste sludge is then thickened and prepared for disposal, often through land application or landfilling In cases where primary and secondary treatments do not meet regulatory standards, tertiary treatment is implemented as an additional step A schematic representation of the various unit operations and processes within a wastewater treatment plant is provided in figure 1.3.
This article provides a concise overview of the key steps in wastewater treatment, including preliminary and primary treatment, secondary treatment, and tertiary treatment Each of these stages is briefly introduced and discussed to give readers a clear understanding of the wastewater treatment process.
Figure 1.3 Schematic of unit operations and processes in a wastewater treatment plant
Current situation of Urban Wastewater Management in Vietnam
1.4.1 The Development of the Urban Drainage System
Between 1858 and 1945, Vietnam began developing urban drainage systems constructed from bricks, designed to manage both wastewater and stormwater The collected wastewater was then discharged into various bodies of water, including lakes, canals, and rivers (Trinh, 2007).
Between 1945 and 1975, urban sewerage systems were expanded haphazardly, lacking proper planning These sewers, primarily constructed from precast concrete and bricks, suffered from damage due to neglect and wartime destruction, leading to broken covers (Trinh, 2007).
Between 1975 and 1990, the focus was primarily on the unification of the South and North, leading to a neglect of the sewerage system by the government Following the onset of renovation in 1990, urban drainage systems gained attention, although they remained a lower priority compared to water supply However, by the early 21st century, authorities recognized the critical importance of sewerage systems as integral components of urban infrastructure.
1.4.2 Current Structure and Operation of Urban Drainage Systems
In this section, the current situation of urban drainage systems in Vietnam including collection systems and treatment systems will be discussed
Many towns with class IV and higher have combined sewer systems comprising precast concrete pipes, brick channels with concrete covers, open channels, and stabilization ponds These sewerage systems were built without a comprehensive urban development master plan, leading to inadequate capacity and insufficient maintenance Additionally, most sewers and canals lack self-cleaning features and proper ventilation, resulting in unpleasant odors during the dry season (Trinh, 2007).
Currently, towns classified as class V lack a comprehensive drainage system for stormwater and wastewater management, as well as wastewater treatment facilities (Trinh, 2007) The prevalence of hygienic latrines among households is alarmingly low, with many relying on bucket toilets and practicing open defecation Although some double vault composting latrines are in use, they are often poorly maintained Additionally, while certain households have septic tanks, they are not connected to the public sewer system, resulting in wastewater being discharged into small ditches or seeping into the surrounding soil Furthermore, improper disposal of rubbish into sewers, canals, and ditches frequently leads to blockages and exacerbates flooding during the rainy season.
The coverage of drainage services in urban areas remains largely unexamined, but experts from the Department of Urban Infrastructure and the Vietnam Drainage and Water Supply Association estimate that it is significantly lower than that of water supply services, with an average coverage of only 40-50% This varies from just 1-2% in class V towns to 70% in larger urban centers In major towns, the drainage length ratio is between 0.2-0.5 meters per person, while in smaller towns it drops to 0.05-0.08 meters per person Many households rely on septic tanks instead of being connected to public sewer systems, leading to wastewater being discharged into open ditches or absorbed into the ground Additionally, some homes with pour-flush toilets release untreated wastewater directly into public sewer systems.
In Vietnam, only Da Lat and Ban Me Thuot have wastewater treatment plants funded by ODA loans from Denmark, achieving a collection rate of merely 40-60% of total wastewater Cities like Ha Long, Vung Tau, and Da Nang have basic wastewater treatment systems, while Hanoi operates two treatment stations in Kim Lien and Truc Bach, which only handle about 1.6% of the city's total wastewater Other towns lack wastewater treatment facilities or are still in the planning stages for such projects (Trinh, 2007).
Urban wastewater is significantly contributing to surface and underground water pollution, with only 60% of hospitals equipped with wastewater treatment plants, and a mere 18% operating them fully Many hospitals lack proper treatment facilities or fail to meet required standards Additionally, wastewater from urban factories is often discharged untreated into public sewer systems, exacerbating the pollution crisis.
During the rainy season, approximately 30% of urban areas experience flooding due to heavy rainfall, with flood durations ranging from one to twelve hours Many previously unaffected areas are now at risk of flooding, primarily due to factors such as illegal connections to drainage systems, an increase in impermeable surfaces, high housing and road density, and the uncontrolled disposal of waste into drainage systems.
1.4.3 The Organizations of Urban Drainage Services in Vietnam
In Vietnam's urban areas, most drainage companies are responsible for both the operation and management of drainage systems Currently, only four companies specialize in drainage services, located in Hanoi, Ho Chi Minh City, Hai Phong, and Ba Ria Vung Tau.
Thirty-two water supply companies also manage drainage services, while thirty-six urban infrastructure firms offer sewerage services alongside additional responsibilities, including solid waste collection, street management, park maintenance, lighting, and funeral services.
Companies managing water drainage systems are tasked with dredging and repairing sewers, operating drainage pumping stations, and maintaining canals and ditches Additionally, many urban drainage firms expand their services to include pipeline construction, sewer pipe production, and the emptying of household septic tanks.
1.4.4 Financial Aspects of Urban Drainage Companies
Drainage companies in developing countries face significant challenges due to insufficient funding for operation and maintenance activities, with provincial or city budgets covering only 50-70% of their needs As a result, effective drainage services are achieved in only half of urban areas, and maintenance tasks, such as dredging sewers, are not performed comprehensively These essential activities are often rushed before the rainy season to mitigate flooding risks.
As a result, many canals and ditches are normally full of sediments Many covers of sewer systems are missing, and broken pipelines are not replaced (Trinh, 2007)
To support urban drainage companies financially, the government implemented Decree 67/2003, which established an environmental protection fee, and Decree 88/2007, which introduced a wastewater discharge fee Decree 88/2007 outlines fees for households discharging wastewater directly into the environment, as well as those connected to the public sewer system Households discharging directly are subject to fees as per Decree 67/2003, with funds allocated to local budgets for environmental protection and sewer maintenance In contrast, households connected to the public sewer system pay a discharge fee incorporated into their water bill, determined by the volume and concentration of their wastewater Revenue from these discharge fees is utilized for the operation and upkeep of sewer systems.
In November 2009, the Prime Minister approved decision 1930/QĐ-TTg, outlining urban development goals through 2025 and a vision for 2050 By 2050, all major towns classified as IV or higher are expected to have comprehensive drainage systems for stormwater and wastewater treatment Smaller towns (class V) and craft villages will utilize centralized or decentralized wastewater treatment facilities The initiative aims to eliminate urban flooding and ensure that wastewater is treated before being released into the environment Additionally, the plan includes specific tasks for stormwater management, sewer operation and maintenance, and wastewater treatment across urban areas, craft villages, hospitals, and industrial zones for the years 2015, 2020, and 2025.
Fundamentals of Benchmarking
The term "benchmarking" has various theories regarding its origin One theory suggests it derives from a British term referring to a reference point in terrain for comparison (Frứydis et al., 2005) Another theory posits that it originated in the fishing industry, where fish were measured against a bench, marking their length with a knife for future size comparisons (Anderson & Petterson).
Benchmarking serves as a standard for comparison, enabling organizations to evaluate their performance against others According to the American Water Works Association, it is a systematic process aimed at identifying best practices, innovative ideas, and effective operating procedures that enhance overall performance By adopting these successful strategies, organizations can significantly improve their own operations.
Benchmarking is defined as a continuous process of measuring and comparing business processes with those of leading organizations, as stated by Bjorn Anderson and Petterson (1996) This practice aims to gather valuable information that assists organizations in identifying and implementing improvements to enhance their performance (Parena & Smeets, 2001).
Benchmarking, initially introduced by Xerox in the late 1970s, aimed to compare operational performance against top competitors, moving beyond traditional financial metrics Today, it serves as a robust tool across various industries, focusing on learning from others to achieve excellence The key objectives of benchmarking include improving performance by learning from industry leaders, understanding business processes, fostering a sense of urgency for change in response to evolving customer demands, developing strategic and operational goals, and promoting creative thinking.
2.1.2 Types and Elements of Benchmarking
Benchmarking can be classified based on the comparison criteria and the subjects involved There are three primary types of benchmarking: performance benchmarking, which evaluates outcomes; process benchmarking, focusing on operational methods; and strategic benchmarking, which examines long-term strategies (Anderson & Petterson, 1996).
As considering whom benchmarking compare against or the level of benchmarking, it can be classified into four types: (1) internal benchmarking, (2) competitive benchmarking, (3) functional benchmarking, (4) generic benchmarking (Anderson & Petterson, 1996)
All these kinds of benchmarking will be referred briefly in this section
Performance benchmarking involves comparing key metrics such as reliability, quality, and speed of products or services to assess a company's standing relative to its competitors This process aims to evaluate a company's performance against industry standards and best practices.
Benchmarking studies aim for learning, adaptation, and improvement by focusing on the underlying causes of performance gaps Process benchmarking goes beyond mere measurement; it analyzes the processes themselves to understand their functioning and the technologies employed This comprehensive approach is essential for effective benchmarking and continuous improvement.
Strategic benchmarking looks for the strategic planning and positioning of a company that makes them succeed The results of strategic benchmarking are long-term (Lankford,
Internal benchmarking involves comparing various departments, units, or countries within the same organization It is primarily utilized by large corporations to evaluate and enhance performance by transferring successful practices from one unit to another This method offers the advantage of easily identifying comparable processes and accessing standardized data and information, facilitating continuous improvement across the organization (Anderson & Petterson, 1996).
Competitive benchmarking is challenging due to the difficulty of obtaining information from competitors This method evaluates an organization's performance, products, and services in comparison to direct competitors within the same industry It necessitates thorough research and a concentrated effort on specific rivals, rather than a broad industry analysis (Lankford, 2002).
Functional benchmarking is the comparison about a specific company function (e.g maintenance) against that function in other company, a non competitor one This type of benchmarking is relatively easy to implement (Barends, 2004)
Generic benchmarking involves identifying companies in unrelated industries that engage in similar processes for information transfer This approach offers significant potential for discovering innovative technologies or practices that can result in groundbreaking advancements.
Benchmarking is an ongoing process that involves several key steps, as illustrated in Figure 2.1, which outlines the five main stages of a benchmarking study This model provides a clear sequence for executing each step, ensuring an effective benchmarking process The descriptions of these stages are based on the work of Anderson & Petterson from 1996.
Figure 2.1 Main steps of a benchmarking process (Source: Anderson & Petterson, 1996)
Effective planning is crucial in the benchmarking process, accounting for approximately 50% of the entire effort This phase involves selecting the process to benchmark, assembling a dedicated benchmarking team, thoroughly understanding and documenting the process in question, and establishing clear performance measures to evaluate its effectiveness.
The first step in the benchmarking process involves identifying suitable partners by establishing a list of criteria they should meet Next, organizations that excel in the desired processes are researched to compile a list of potential partners After reviewing the candidates, the top organizations are selected, and the final task is to invite them to participate in the benchmarking study.
Observe The purpose of observing step is to understand the benchmarking partners
In this step, key tasks involve assessing information requirements, selecting appropriate data collection methods, and gathering information through observation and inquiry Data should be collected at three critical levels: first, the performance level, which evaluates how the partner compares to others; second, the methods and practices that facilitate achieving these performance levels; and third, the enablers that support the execution of processes in accordance with the established practices or methods.
International Benchmarking System in Water Industry
The primary goal of any benchmarking study is to drive adaptation and improvement; without these outcomes, the full potential of benchmarking remains untapped This process involves several key tasks: effectively communicating the analysis findings, setting functional goals for enhancement, and creating a comprehensive implementation plan for the improvements.
To successfully implement a plan, it is crucial to engage the process owner and stakeholders affected by the changes prior to execution Once the plan is in action, continuous monitoring of progress is essential, allowing for necessary adjustments along the way Finally, a comprehensive report should be prepared to summarize the study's findings and outcomes.
Recycle To get an improvement, benchmarking should be continued by adjusting the benchmarks for already done processes and benchmarking new areas or processes
2.2 International Benchmarking System in Water Industry
2.2.1 Benchmarking of large Municipal Wastewater Treatment Plants in Austria
The Austrian benchmarking system for wastewater treatment plants, developed between 1999 and 2004, has analyzed around 100 facilities serving populations of 2,000 to 1 million (EWA&DWA workshop report, 2009) Its primary goal is to establish process indicators that identify best practices and benchmarks By comparing a wastewater treatment plant's performance against these benchmarks, potential cost reductions and optimization opportunities can be identified (Lindtner et al., 2008).
The article identifies four primary processes and two supporting processes, as illustrated in figure 2.2 Each main process is further broken down into sub-processes, with all associated costs, including annual total costs and operation and maintenance expenses, categorized accordingly.
Figure 2.2 Extended process model for wastewater treatment plants above 100,000 PE
To establish comparable process indicators, treatment plants were categorized by capacity ranges Benchmark plants were identified as those demonstrating the lowest costs while adhering to specific criteria: (1) effluent quality must meet Austrian emission standards, (2) data must be verified through mass balance or other reliable methods, and (3) the plants should handle typical municipal wastewater without significant industrial influence.
Benchmarking processes consist of three key steps: data acquisition, data processing, and experience exchange Data is collected, transferred, and communicated through the internet (Report of EWA&DWA workshop, 2009) There are two categories of data: operating data, which is updated annually, and conservative data, such as design capacity and tank volume, which is only modified when upgrades occur (Lindtner et al.).
Data quality assessment involves conducting plausibility checks to ensure data falls within a feasible range Financial data is evaluated through variance analysis, comparing current figures with those from the previous year Experience exchange occurs through individual consultations and workshops, where benchmarking experts meet with plant managers to address data quality issues and refine reports Following these discussions, corrected or improved data is incorporated into the final report To facilitate learning from best practices, workshops were organized for benchmarking participants.
Figure 2.3 Methodology for the development of process performance indicators
(Source: Report of EWA&DWA workshop, 2009)
Benchmarking studies in wastewater treatment plants reveal that the total yearly cost per population equivalent (PE) varies significantly, ranging from €26 for larger facilities to €71 for smaller ones, based on a chemical oxygen demand (COD) of 110 g COD/PE/day Additionally, the operating costs are estimated to fall between €10 and €22.
€/PE/a, where mechanical-biological wastewater treatment account for 45% and the rest 55% is for additional sludge treatment and disposal (Lindtner, et al., 2004)
The Canadian National Water and Wastewater Benchmarking Initiatives began its project in 1997, focusing on the wastewater sector in four cities By 2001, the initiative expanded to include the water supply sector, and now encompasses 42 facilities across both sectors (Koelbl, 2009).
Since 2001, process benchmarking activities have been conducted alongside corporate benchmarking efforts, facilitated by various task forces comprising participant members These task forces are tasked with identifying best practice sources, such as methodologies from participants and the International Water Association (IWA) Their responsibilities include developing action plans based on these best practices, fostering networks among experts and participants, and initially piloting implementations in select facilities to refine these practices for broader application (Koelbl, 2009).
Current process benchmarking projects are carried on these following topics: (1) water loss management, (2) maintenance planning (collection, distribution, and drainage), (3) complex facilities maintenance planning, (4) sustainable funding through asset management,
(5) wastewater treatment plant optimization, (6) energy management, (7) inflow and infiltration, (8) succession planning, (9) attendance management, (10) storm-water management (Koelbl, 2009)
2.2.3 North European Benchmarking Co-operation
Established in 2004 by Scandinavian and Dutch national water associations, the North European Benchmarking Co-operation (NEBC) initiated its first international water benchmarking pilot in 2006 By the end of 2007, ten European countries had participated in this benchmarking initiative Utilizing the Performance Indicators (PIs) system from the International Water Association (IWA), NEBC developed a three-level benchmarking model to evaluate facilities at varying levels The organization emphasizes five key performance areas: water quality, reliability, service quality, sustainability, and financial efficiency (Dane & Schmitz, 2008).
NEBC's benchmarking program encompasses both the water and wastewater sectors, initially piloted in 2006 using the Netherlands' methodology for drinking water However, participants found this approach too complex for first-time users Consequently, a new methodology was created for the second pilot based on the IWA PIs system This benchmarking model features three levels of participation: basic, metric, and advanced, enabling smaller or less experienced facilities to engage at a level appropriate to their developmental stage.
Figure 2.4 NEBC’s benchmarking model (Source: Dane & Schmitz, 2008)
The NEBC benchmarking process encompasses seven key phases: First, the preparation phase ensures new participants receive all necessary information Next, during the data collection phase, participants gather data online with support from NEBC coordinators The analysis phase follows, where submitted data is thoroughly reviewed In the reporting phase, a report highlighting essential performance indicators (PIs) is generated to assess facility performance and identify gaps The best practice phase involves discussions to pinpoint successful strategies and develop action plans Subsequently, an evaluation phase is conducted to identify improvement areas through participant and coordinator feedback Finally, the closing down phase marks the conclusion of the benchmarking process and the initiation of a new cycle.
NEBC’s second international benchmarking pilot scheme was completed in April 2008, got positive results and feedback from participants and NEBC intend to proceed with the international benchmarking activities (Dane & Schmitz, 2008)
2.2.4 Benchmarking for Wastewater Services in Germany
In 1996-1997, Germany was the first to adopt the benchmarking method in wastewater services, a practice that relies on two key factors for success: voluntary participation and the confidential handling of information (Koelbl, 2009).
In 2005, six prominent German water industry associations—ATT, BDEW, DBVW, DVGW, DWA, and VKU—collaborated to establish a benchmarking agreement aimed at enhancing the water sector This agreement outlines the methodology, objectives, data handling, and public reporting of benchmarking results While initial reports primarily presented statistical data, guidelines for benchmarking in water and wastewater enterprises were published to assist small and medium-sized plants Additionally, a public document featuring key performance indicators was released to ensure compatibility in benchmarking practices across Germany (Report of EWA&DWA workshop, 2009).
There are more than 27 benchmarking projects being currently carried out in Germany
Process Benchmarking in Wastewater Sector
Though there are many process benchmarking projects in different countries around the world, a worldwide acceptation of definition and steps of this type of benchmarking has not been defined (Koelbl, 2009)
Process benchmarking, as defined by Joerg Koelbl, is a management methodology aimed at comparing and optimizing performance in process operations It involves a clear process structure that divides processes into sub-processes and individual tasks, allowing for the calculation of performance indicators for both the overall process and its components In addition to quantitative comparisons, documenting the process operation is essential Both economic factors and quality assessments must be considered in the analysis A key aspect of process benchmarking is sharing experiences through workshops, and after conducting cause analyses and implementing measures, the effectiveness of optimizations is verified through subsequent performance comparisons.
2.3.2 The Objectives of Process Benchmarking
Process benchmarking focus on detail optimization potentials therefore it is required to gain a basis of process operation To achieve this aim, process benchmarking should answer these following questions:
- How are the overall process and sub-processes operated?
- How much do the main process and sub-processes cost?
- What is the working time of the main process and sub-processes?
- Are the defined quality criteria complied?
- How do the other facilities perform and why are there differences?
Water utilities can achieve significant operational benefits through process benchmarking, leading to reduced costs while maintaining the same quality of operations or enhancing the quality of operations without increasing expenses.
The macro economic benefits of increasing efficiency and quality that can be seen from water supply sector
To achieve high-quality process benchmarking, it is essential to establish a clear hierarchical process structure This involves specifying the input and output data for each process, which helps to delineate the primary process and its sub-processes This crucial step is known as process mapping.
To effectively benchmark the technical and economic aspects of each process and sub-process, it is essential to establish quality criteria Additionally, understanding the framework conditions and operational differences is crucial (Koelbl, 2009).
An effective cost accounting system must meet the requirements for collecting costs necessary for process benchmarking To achieve this, it is essential to develop a suitable cost allocation system that gathers data at the sub-process level while managing the total costs of the overall process.
After setting process performance indicators a performance comparison is implemented between groups of participants
Before sharing comparison results, it is essential to discuss them internally Knowledge exchange is most effective through workshops, where these results can be analyzed to identify best practices To achieve the goal of becoming "best in class," organizations must recognize and integrate these best practices into their operational processes.
The IWA manual on best practices for process benchmarking in the water sector highlights a holistic approach exemplified by countries like the Netherlands and those in Scandinavia This methodology involves a comprehensive analysis of all processes within a water facility, starting from water extraction and concluding with the sales to customers.
Figure 2.5 Procedure of process benchmarking
Selective process benchmarking, utilized in countries like Australia and Bavaria, Germany, focuses on analyzing specific processes rather than evaluating all processes comprehensively A comparison of the holistic and selective approaches is illustrated in Table 2.1.
Table 2.1 Holistic approach versus selective approach in process benchmarking a
- Analyze all processes in the operation of a water facility
- Analyze the selected processes in the operation
- Practices in the Netherlands and
- Practices in Australia, Bavaria in Germany
- Advantage: closed cost allocation system - Advantage: simple cost allocation system; more detailed analyses
- Disadvantage: highly aggregated sequences of single tasks; coarse division
- Disadvantage: no closed cost allocation system a: From Koelbl, 2009