Introduction to Decentralized Infrastructure for Wastewater Treatment and Water Reclamation

Abstract

This chapter highlights the development of wastewater infrastructure in the United States and describes how and why decentralized infrastructure has evolved to become a critical component of a twenty-first century infrastructure. Decentralized infrastructure consists of approaches, technologies, and systems that can be used at buildings and developments with indoor water use and wastewater flows that span from 100 to 100,000 gal/day or more. Several examples are provided to illustrate the characteristics and applications of decentralized approaches, technologies and systems that can be used to achieve effective treatment and disposal of wastewaters, provide a source of reclaimed water, and/or to minimize resource consumption and enable resource recovery.

Slides of Chapter 1: Decentralized Water Reclamation

1.1.1 Chapter 1: Introduction to Decentralized Infrastructure for Wastewater Treatment and Water Reclamation

Contents

• 1-1. Introduction

• 1-2. Wastewater perspectives – risks and resource value

• 1-3. Wastewater infrastructure – evolution and status

• 1-4. Decentralized infrastructure – modern approaches, technologies, systems

• 1-5. Summary

1.1.1.1 1-1. Introduction

• ■ Water use generates wastewate rs

  • • Humans use water for various purposes including drinking, bathing, fishing, swimming, food production, etc.

    • ○ Water use often requires water treatment and supply, which typically involves use of energy, chemicals, and materials

  • • The use of water by humans generates wastewaters

    • ○ Wastewaters contain chemical and microbial constituents and management is needed to mitigate public health and environmental risks

    • ○ Wastewaters also contain water, organic matter, nutrients, and energy, which can have sufficient value to warrant recovery and use

  • • Water and wastewater infrastructure are i nextricably linked

    • ○ Wastewater treatment for water reclamation and reuse is a natural or engineered outcome (Fig. 1.1)

      Fig. 1.1

      

      Water and w astewater i nfrastructure are inextricably linked by the actions of humans

• ■ Water and wastewater infrastructure are critical to achieving and sustaining a healthy society

  • • United Nations Human Development Index (HDI) is a measure of the quality of life and prosperity in a society (Fig. 1.2)

    Fig. 1.2

    

    Illustration of the UN human development index (after UN 2010)

  • • Along a nation’s timeline of evolving to a h igh HDI:

    • ○ Efforts are initially focused on providing safe drinking water

    • ○ As safe drinking water becomes widely available, health and well-being increase

    • ○ The population can become more affluent, which leads to increased water use and wastewater generation

    • ○ Efforts then move to include effective management of wastewaters

• ■ Modern solutions for water and wastewater in frastructure need to be effective while being affordable, socially acceptable, and sustainable

  • • Modern solutions for safe drinking water should:

    • ○ Protect our raw water supply sources

    • ○ Minimize chemicals and energy used in water treatment and delivery

    • ○ Minimize drinking water used for cleaning and waste carriage

  • • Modern solutions for wastewater management should:

    • ○ Minimize wastewater volumes and reduce pollutant loads

    • ○ Minimize the use of chemicals and energy in treating wastewater to reclaim and clean the water

    • ○ Maximize the beneficial recovery and reuse of wastewater resources including water, nutrients, organic matter and energy

• ■ So, where are we today…? Where are we going…?

  • • Answering this question depends on the context

    • ○ In the United States and similar industrialized countries

    • ○ In developing countries and regions of the world

  • • An assessment of where we are and where we are going should include consideration of attributes such as shown in Fig. 1.3

    Fig. 1.3

    

    Timeline attributes important to assessing the status and future of water and wastewater infrastructure in a particular s ituation

    • ○ Acceptability and sustainability attributes can be particularly difficult to assess

1.1.1.2 1-2. Wastewater Perspectives

• ■ Wastewater has long been recognized for the risks it poses

  • • Wastewater can pose inherent risks to human health or the environment due to its physical, chemical and biological constituents

  • • Fundamentally, the challenge is to assess the magnitude of the risks in a given situation and decide on the most appropriate way to manage those risks

    • ○ For example, pathogenic bacteria, virus, and protozoa are present in wastewater, and infectious disease could result if they are not removed or inactivated before an effluent reaches a receiving environment where humans can contact and ingest the water (e.g., drinking water, bathing beaches, shellfish beds)

    • ○ Also, if excessive levels of nitrogen and phosphorus in wastewater are input to sensitive surface waters (e.g., pristine lakes, estuaries), this could result in undesirable ecosystem changes (e.g., increased productivity and eutrophication)

  • • Design and implementation to manage risks

    • ○ Risk-based design and implementation of wastewater systems is desirable but can be quite difficult to explicitly accomplish

    • ○ One could state the ultimate goal as being system design and implementation so that (1) there is no infectious disease attributable to a wastewater system, and (2) there is no measurable change in an ecosystem attributable to wastewater system inputs

    • ○ Clearly, in a given setting, a wastewater system that provides no treatment at all may present the highest risk, while increasing levels of reliable treatment effectiveness could yield reduced levels of risk

    • ○ However, since risk management requires consideration of nontechnical issues, such as acceptability and sustainability, the most advanced treatment system may not be the best overall risk management solution

  • • Federal and state requirements for design and implementation

    • ○ Federal and state requirements may be based in part on risk-based considerations but requirements for selection, design, and implementation are typically not explicitly risk-based

    • ○ Guidelines, criteria and standards can be used to define the level of wastewater treatment required and the quality of the effluent produced before its disposition or use

    • ○ Treatment and water quality requirements are not always the same in multiple jurisdictions (e.g., requirements of one state vs. another in the United States or from one country to another)

      • * The reason for differences is often not clear, but one explanation is that public health or environmental effects associated with pollutants and pathogens in water involves complex and sometimes uncertain concentration-risk relationships that require subjective interpretation

• ■ Wastewater is increasingly being recognized for the resources it contains

  • • Wastewater represents a resource by virtue of its content of:

    • ○ Water—Water reclaimed from wastewater represents a valuable alternative water supply source

    • ○ Organic matter—Organic matter recovered from wastewater can be used as a soil amendment or fertilizer

    • ○ Nutrients—Nutrients (e.g., N, P, K) in wastewater represent a potentially valuable alternative to commercial chemical fertilizers

    • ○ Energy content—Energy can be recovered from the organic matter in wastewater (e.g., biogas production)

  • • The challenge is to select, design and implement approaches, technologies and systems that can recover resources of value in a given situation while also mitigating risks

1.1.1.3 1-3. Wastewater Infrastructure

• ■ In the United States during the 20th century, major U.S. investments were made leading to:

  • • Knowledge, laws, and regulations

  • • Modernized fixtures and appliances and plumbing systems

  • • Construction of water and wastewater infrastructure^a

    • ○ New and improved wastewater collection and treatment systems

    • ○ Expansion of service areas and increased accessibility

• ■ At the close of the 20th century, most of the U.S. population had acceptable and affordable access to:

  • • Safe drinking water

  • • Adequate wastewater management

    ^a Infrastructure = The basic physical and organizational structures and facilities needed.

• ■ Features of wastewater infrastructure in the United States

  • • Infrastructure features are highlighted in Table 1.1 and Fig. 1.4

    Table. 1.1 Features of wastewater infrastructure in the United States around the end of the 20th century

    Fig. 1.4

    

    Illustration of classic c entralized (a) and decentralized infrastructure (b, c). Note: Decentralized infrastructure includes onsite systems (c)

  • • What distinguishes “decentralized” and “onsite” infrastructure?

    • ○ There are subtle differences

      • * Onsite—Involves applications where wastewater treatment and discharge/reuse occurs on the same property where the source of the wastewater generation is located

        • Example: a property with a single family home with a treatment and reuse system on that property

      • * Decentralized—Involves applications where wastewater treatment and discharge/reuse occurs on a property close to the location(s) where the source(s) of wastewater generation is (are) located

        • Example: multiple properties with a collection network and a treatment site located near the development

    • ○ Decentralized terminology will be used throughout this book as it is commonly used today and it does encompass onsite

• ■ Evolution of 20th century wastewater infrastructur e

  • • During the latter part of the 20th century, major U.S. Federal and State programs provided funding for construction of new and expanded centralized infrastructure (Table 1.2)

    Table 1.2 Government funding that promoted construction of centralized infrastructure for wastewater management in the United States (after Anderson and Otis 2000)

    • ○ This was done to improve the quality of life in urbanized areas—often located near rivers, lakes, and coastal zones—where population densities were high and the risks associated with wastewater were also high

  • • During this time there was little funding available for construction of decentralized systems serving homes and businesses

    • ○ The wastewater-related risks were lower due to low population densities and locations in rural areas

    • ○ In addition some viewed decentralized systems as temporary and only needed until they were replaced by a centralized system

  • • During much of the 20th century, decentralized wastewater systems were used in rural areas and other areas with low population densities

    • ○ Many of these systems were not designed or implemented to achieve treatment and reuse objectives over long-term use

    • ○ Not surprisingly, such systems often suffered performance deficiencies ranging from hydraulic failures to localized contamination of groundwaters and surface waters

      • * These were attributed to varied causes including poor system siting, improper design, faulty installation, and/or inadequate operation and maintenance

    • ○ During the latter part of the 20th century, research and educational initiatives, along with changes in regulatory requirements and advancements in management and performance assurance, helped improve the standard-of-practice and mitigate performance deficiencies

  • • Growth in centralized infrastructure for wastewater management began to level off in the 1970s

    • ○ Many urbanized areas of the United States had new and expanded centralized infrastructure for wastewater management

    • ○ It was increasingly clear that larger centralized systems were not technically feasible or affordable to serve buildings and developments located in most rural and peri-urban areas and many small towns

  • • Then, during the 1990s, concerns grew a bout the sustainability of large centralized infrastructure (Table 1.3)

    Table 1.3 Example reasons for growing concerns expressed during the 1990s about the sustainability of large centralized infrastructure for wastewater management

  • • At the same time, there was growing interest in decentralized infrastructure due to the potential benefits it might yield (Table 1.4)

    Table 1.4 Potential benefits to sustainability pr ovided by decentralized infrastructure for wastewater treatment and water reclamation

• ■ Advancing decentralized infrastructure in the 21st century

  • •  Activities and events around the turn of the Century helped promote decentralized infrastructure into the 21st century

  • •  1997—The U.S. Environmental Protection Agency (USEPA) prepared a report to the U.S. Congress on the appropriate use of onsite and decentralized systems and concluded that:

    • ○ “Adequately managed decentralized wastewater systems are a cost-effective and long-term option for meeting public health and water quality goals.”—www.epa.gov/owm/mtb/decent/response/index.htm

      In their report (USEPA 1997), USEPA identified five major barriers to overcome:

      • * Restricted access to funding for system construction and operation

      • * Legislative and regulatory constraints on funding and implementation

      • * Existing engineering practices favoring centralized infrastructure

      • * Misinformation and limited knowledge about decentralized systems

      • * Providing effective management of decentralized infrastructure

  • • 1997—U.S. Congress with USEPA, initiated the National Decentralized Water Resources Capacity Development Project (NDWRCDP) http://www.ndwrcdp.org/

    • ○ An initial $8.2 M in funding supported projects to overcome the barriers identified in the 1997 USEPA report

    • ○ Additional funding was provided in subsequent phases

  • • 2000s—U.S. Congress provides $15.6 M for projects in six areas to demonstrate decentralized technologies and management

  • • 2002 and 2003—USEPA published a new “Onsite Wastewater Treatment Systems Design Manual” and “Voluntary Guidelines for Management of Onsite and Clustered Wastewater Treatment Systems”

  • • 2003—NDWRCDP sponsored workshops focused on “Soft Path Integrated Water Resource Management”

  • • 2005—The U.N. Millennium project called out the need for clean water and sanitation worldwide

    • ○ The basis for the worldwide need as assessed at the time included:

      • * 2.5 billion people lacked appropriate sanitation

      • * 1.2 billion people lacked clean water supply

      • * 3.4 million people died yearly due to waterborne disease (Fig. 1.5)

        Fig. 1.5

        

        Illustration of water and wastewater in a low HDI setting

    • ○ A U.N. Millennium Development Goal was to reduce by 50% the number of people without clean water and sanitation by 2015

    • ○ Decentralized approaches, technologies and systems were viewed as necessary and appropriate

  • • 2007—“Baltimore Charter for Sustainable Water Systems” was prepared and signed by individuals from countries worldwide

    “Water is at the heart of all life. In the past, we built water and wastewater infrastructure to protect ourselves from diseases, floods, and droughts. Now we see that fundamental life systems are in danger of collapsing from the disruptions and stresses caused by this infrastructure.

    New and evolving water technologies and institutions that mimic and work with nature will restore our human and natural ecology across lots, neighborhoods, cities, and watersheds. We need to work together in our homes, our communities, our workplaces, and our governments to seize the opportunities to put these new designs in place. …

    We commit to implementing more sustainable water systems by expanding uses and opening new markets for small-scale treatment processes, advancing research on micro-biological and macro-ecological scales, inventing new technologies based on nature’s lessons, creating new management and financial institutions, reforming government policies and regulations, and elevating water literacy and appreciation in the public.”

    Source: http://www.ndwrcdp.org/documents/Balto_Charter.pdf

  • • 2008–2009—U.S. National Academy of Engineering panel reviews and special reports emphasized the need for sustainable water and wastewater infrastructure…

    …including decentralized approaches, technologies and systems (Fig. 1.6)

    Fig. 1.6

    

    Cover pages from two recent U.S. National Academy publications

  • • 2009—The Decentralized Water Resources Collaborative (DWRC) emerged

    • ○ DWRC is a cooperative effort managed by the Water Environment Research Foundation (WERF) and funded by the USEPA (Fig. 1.7)

      Fig. 1.7

      

      Home page of the WERF website for decentralized systems. www.werf.org/AM/Template.cfm?Section=Decentralized_Systems

    • ○ DWRC supports research and educational initiatives focused on decentralized wastewater and stormwater

    • ○ DWRC research reports and other products were developed during 2009–2011

    • ○ DWRC research and products dissemination encompasses septic tanks and onsite systems, watershed scale solutions, urban applications and stormwater

    • ○ DWRC products include: technical reports, modeling tools, and decision aids available through a website, FAQ guide, product matrix guide, and videos (Fig. 1.8)

      Fig. 1.8

      

      Home page of the DWRC website for onsite and decentralized systems. www.decentralizedwater.org/

  • •  2011—U.S. National Science Foundation sponsors a major Engineering Research Center on water

    • ○  The NSF ERC on “Reinventing the Nation’s Urban Water Infrastructure (ReNUWIt)” was launched in August 2011 (Fig. 1.9)

      Fig. 1.9

      

      Home page of the website for the NSF research center for reinventing urban water infrastructure. www.urbanwatererc.org/

    • ○ ReNUWIt has a broad array of research and educational thrusts, and decentralized approaches and the associated technologies are one facet of the ERC

  • • 2012—U.S. Decentralized Partnership to promote the use and improve the performance of decentralized wastewater treatment

    • ○ The U.S. Decentralized Partnership is an agreement between the USEPA and 16 partner organizations to work collaboratively at the national level to improve decentralized system performance (Fig. 1.10)

      Fig. 1.10

      

      The EPA decentralized memorandum of understanding partnership papers were released in 2012 (USEPA 2012). (http://water.epa.gov/infrastructure/septic/Decentralized-MOU-Partnership-Products.cfm)

    • ○  Four papers described decentralized system uses and benefits:

      • Introduction to Decentralized Wastewater Treatment: A Sensible Solution

      • Decentralized Wastewater Treatment Can be Cost Effective and Economical

      • Decentralized Wastewater Treatment Can Be Green and Sustainable

      • Decentralized Wastewater Treatment Can Protect the Environment, Public Health and Water Quality

• ■ In the 21st century, w ater and wastewater paradigms are increasingly driven by sustainability concerns

  • • View of water more holistically, differentiated by quality and intended uses rather than lumped as drinking water, stormwater, or wastewater

  • • Approaches, technologies and systems are increasingly being judged based on their sustainability attributes, including

    • ○ Human and environmental interactions and effects

    • ○ Resilience to natural or human influenced upsets

    • ○ Ability to deal with climate change

• ■ Decentralized infrastructure in the 21st century

  • • Decentralized approaches, technologies and systems can contribute to a 21st century sustainable water and wastewater infrastructure

    • ○ To help promote and accomplish this, it is important to clearly understand decentralized infrastructure attributes and the potential uses and benefits in different applications

  • • It is also critical to to clearly recognize and appreciate the differences between modern infrastructure and legacy systems

    • ○ Modern 21st century decentralized infrastructure can be implemented in rural, peri-urban, suburban and urban areas for longer-term, high efficiency treatment and often water reuse and resource recovery

    • ○ In contrast, older 20th century dece ntralized systems are often legacy systems that were installed in rural areas for shorter-term waste disposal

1.1.1.4 1-4. Decentralized Infrastructure

• ■ Decentralized infrastructure is normally deployed to help achieve one or more of the following project goals

  • • Effective treatment and disposal of wastewaters in areas where a decentralized system is the only option or where decentralized systems offer desired benefits

  • • Treatment of wastewaters to provide a reclaimed water source in areas where decentralized systems can yield benefits by co-locating wastewater generation near a water reuse site

  • • Minimized resource consumption and maximized resource recovery in areas where these are desired by the project owners for various reasons such as to support an environmental consciousness, realize cost incentives or savings, and earn points to achieve a desired sustainability rating

    Note: Decentralized infrastructure can also be used for stormwater and other impaired waters.

• ■ Decentralized infrastructure components include those listed below (Fig. 1.11)

  Fig. 1.11

  

  Examples of system components : (a) urine diverting toilet, (b) septic tank and pump vault, (c) small diameter sewer, (d) primary settling and recirculation fiberglass tanks, (e) aerobic treatment unit, (f) recirculating textile media biofilters, (g) recirculating foam filter in a shipping container, (h) membrane bioreactor, (i) subsurface flow constructed wetland, (j) chamber-equipped subsurface soil treatment unit, (k) landscape drip dispersal unit, (l) denitrifying wood chip biofilter, (m) ultraviolet light disinfection unit

  • • Source modification options

    • ○ Ultra efficient fixtures and appliances

    • ○ Waste stream source separation

  • • Collection and conveyance options

  • • Treatment options

    • ○ Bioreactors

    • ○ Recirculating biofilters

    • ○ Membrane bioreactors

    • ○ Constructed wetlands

    • ○ Subsurface soil infiltration

    • ○ Landscape drip dispersal

    • ○ Nutrient removal units

    • ○ Disinfection units

  • • Sensors and intelligent control options

  • • Discharge and reuse/recovery options

    • ○ Surface or subsurface discharge and groundwater recharge

    • ○ Nonpotable water reuse

    • ○ Recovery of wastewater organic matter, nutrients, energy

• ■ Applications of decentralized infrastructure are varied

  • • Development types include (Figs. 1.12 and 1.13):

    Fig. 1.12

    

    Illustration of developments where decentralized infrastructure has been deployed: (a) individual home, (b) school, (c) restaurant in rural areas, (d) apartment building or (e) strip mall in suburban areas, (f) homes and businesses in a small town or (g) high rise office and condominium buildings in a city

    • ○ Single homes, businesses, and institutions in rural and peri-urban areas

    • ○ Neighborhood and commercial developments in small towns and suburban areas

    • ○ Buildings and higher density developments in larger cities

      Fig. 1.13

      

      Illustration of a city center area with nearby urbanizing areas where decentralized infrastructure can be deployed along with centralized infrastructure. (Note that management of decentralized infrastructure can be handled by a single central authority or by multiple authorities)

  • • Decentralized infrastructure can handle a wide range of design flows (Table 1.5)

    Table 1.5 Decentralized systems can handle a wid e range of design flows^a

• ■ Decentralized systems are configured from approaches and technologies

  • • Compatible components are configured for a goal (Fig. 1.14)

    Fig. 1.14

    

    Illustration of example approaches and technologies that can be used to configure a decentralized system for a particular discharge or reuse goal

  • • A few example system configurations are illustrated in the following pages

  • • Illustration of a system for individual residential units and businesses in rural and peri-urban areas

    • ○ Where land area is available and soil and site conditions are suitable for soil-based treatment (Fig. 1.15)

      Fig. 1.15

      

      Example of a system and illustration of k ey components for use at single houses and businesses where soil and site conditions are suitable for soil-based treatment

    • ○ Where land area is available and soil and site conditions are suitable for soil-based treatment and water reuse and nutrient recovery is desired (Fig. 1.16)

      Fig. 1.16

      

      Example of a system and illustration of key components for use where soil and site conditions are suitable for soil-based treatment a nd water reuse and nutrient recovery is desired

    • ○ Where advanced treatment is needed for discharge to a local inland stream or lake (Fig. 1.17)

      Fig. 1.17

      

      Example of a system and illustration of key components for use where advanced treatment is needed to enable discharge to a local inl and stream or lake

  • • Illustration of a system for multiple buildings in developments or small towns (Fig. 1.18)

    Fig. 1.18

    

    Example of a system and ill ustration of key components used to serve a development or small town including wastewater collection and conveyance to a local site for treatment and reuse

    • ○ Where land use planning and density characteristics require wastewater collection and conveyance to a local treatment and reuse site

  • • Illustration of a system for high rise buildings in highly urbanized settings and cities (Fig. 1.19)

    Fig. 1.19

    

    Example of a membrane bioreactor system serving a high rise apartment building in a major urban area to produce reclaimed water for nonpotable reuse and help earn LEED certification. (Photographs are of the Solaire building in Battery Park City, NY which has 250 apartment units. http://www.werf.org/i/c/Decentralizedproject/When_to_Consider_Dis.aspx)

    • ○ Where water reuse and green building certification is desired

• ■ System selection and design can be informed using a growing array of models and other decision aids

  • • Analytical models for design and performance (Geza et al. 2014, Fig. 1.20)

    Fig. 1.20

    

    Simulations with STUMOD re vealing there is a 50 % probability of 70 % nitrogen removal at 60-cm depth in a subsurface soil treatment unit under the assumed conditions

  • • Numerical models for simulating performance under complex conditions

  • • Watershed models to simulate cumulative effects on water resources (Siegrist et al. 2005, Fig. 1.21)

    Fig. 1.21

    

    Simulations with the watershed model , WARMF, revealing there would be an increase in nutrient loading to the Blue River if onsite systems are replaced by a centralized system

• ■ Management of decentralized infrastructure is critical to achieving and sustaining a performance outcome

  • • What is meant by “management”?

  • • Management involves public and/or private entities and a set of activities, often organized within a jurisdiction, to assure:

    • ○ Decentralized systems are properly considered during infrastructure and land use planning, and

    • ○ If selected they are properly designed, constructed, and operated so the performance planned for are sustainably achieved

  • • As decentralized systems have evolved to become a permanent part of the U.S. water and wastewater infrastructure, the need for, and critical role of, approaches for effective management have also evolved (refer to Chap. 2)

1.1.1.5 1-5. Summary

• ■ Decentralized wastewater infrastructure has evolved and can now provide sustainable long-term solutions for:

  • • Effective treatment and disposal of wastewaters

  • • Treatment of wastewaters to provide a reclaimed water source

  • • Minimized resource consumption and enhanced recovery

• ■ Modern decentralized infrastructure encompasses approaches, technologies and systems that include:

  • • Ultra high water use efficiency fixtures and appliances and in-building source separation

  • • Small diameter wastewater collection and conveyance networks

  • • Reactor-based and landscape-based treatment unit operations

  • • System monitoring and performance assurance methods

  • • Management systems to help assure long-term sustainability