Urban Water Systems – Page 2 – Environmental Stewardship and Urban Infrastructure

November 2, 2016

Constructed Wetlands I

One of the alternative solutions to wastewater treatments that are widely used nowadays are the constructed wetlands. These wetlands are shallow pools developed specifically for storm or waste water treatment that create growing conditions suitable for wetland plants. They are great alternatives to remove contaminants from wastewater, and have been used for decades now.
Constructed wetlands have the same properties as natural wetlands, and are designed to provide water quality benefits through various process that will ultimately minimize pollution prior to the water entry to streams. They also act as biofilters, and remove sediments and pollutants such as heavy metals from the water, and can even serve as wildlife habitat even though that is outside the scope of its main purposes.

There are 2 types of constructed wetlands:

Surface Flow Systems (Free water surface):

A surface flow constructed wetland have standing water at the surface, and can be used as a tertiary treatment facility at a wastewater treatment plant. This system consist of a basin full of water, and macrophytes roots planted that emerge at the water surface. The effluent water is treated as it flows over the soil, and organic material is removed through microbial degradation.

The figure below shows a surface flow constructed wetland.

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Subsurface Flow Systems:

Subsurface systems have no visible standing water, and are designed so that the wastewater flows through a gravel substrate beneath the surface vegetation.The wastewater passes through a sand medium on which plants are rooted. A gravel medium (generally limestone or volcanic rock ) can be used as well and is mainly deployed in horizontal flow systems though it does not work as efficiently as sand.
In the vertical flow constructed wetland, the effluent moves vertically from the planted layer down through the substrate and out. In the horizontal flow CW the effluent moves horizontally, parallel to the surface.

The figure below shows a subsurface flow constructed wetland.

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Constructed wetlands are then extremely important to wastewater and play a big role in gray water systems. Just like other major systems, they include all components necessary to the efficient treatment of gray water such as: collection of water, treatment, disinfection, and distribution.

References:

http://www.ces.uoguelph.ca/water/NCR/ConstructedWetlands.pdf

https://www.epa.gov/wetlands/constructed-wetlands

http://www.gov.pe.ca/photos/original/eef_wildlife_p1.pdf

November 2, 2016

Constructed Wetlands II

This weeks learning, titled “Design for Water conservation and Waste-Water management” explored how the ecosystem approach to urban infrastructure design required engineers to consider the whole water cycle. That allows us as engineers to build infrastructure that restores the natural balance of water in ecosystems. While much of the reading was highly applicable and interesting, I was particularly intrigued by the idea of constructed wetlands and decided to investigate this topic further.

4130876_orig Above – A beautiful constructed wetland in action at the Lincoln Park Zoo in the USA. Source:http://www.acornponds.com/bog-filtration.html

What is a Constructed Wetland?

Constructed wetlands are engineered systems that use natural functions of vegetation, soil, and organisms to treat different water streams. Depending on the type of wastewater that has to be treated the system has to be adjusted accordingly which means that pre- or post-treatments might be necessary.

Constructed wetlands can be designed to emulate the features of natural wetlands, such as acting as biological-filters or removing sediments and pollutants such as heavy metals from the water. Constructed wetlands sometimes serve as a habitat for native and migratory wildlife, although that is usually not their main purpose.

There are three main types of Constructed Wetland:

Subsurface flow constructed wetland – this wetland can be either with vertical flow (the effluent moves vertically, from the planted layer down through the substrate and out) or with horizontal flow (the effluent moves horizontally, parallel to the surface)
Surface flow constructed wetland
Floating treatment wetland

Cost of Constructed Wetlands

Constructed wetlands are self-sustaining, and thus their lifetime costs are significantly lower than those of conventional treatment systems. Often their capital costs are also lower compared to conventional treatment systems. They do take up significant space, and are therefore not preferred where real estate costs are high. Overall, constructed wetlands are generally significantly cheaper than conventional treatment systems.

How do they Work?

A constructed wetland is an engineered sequence of water bodies designed to filter and treat waterborne pollutants found in sewage, industrial effluent or storm water runoff. Constructed wetlands are used for wastewater treatment or for greywater treatment, and can be incorporated into an ecological sanitation approach. They can be used after a septic tank for primary treatment, in order to separate the solids from the liquid effluent. Some CW designs however do not use upfront primary treatment.

Vegetation in a wetland provides a substrate (roots, stems, and leaves) upon which microorganisms can grow as they break down organic materials. This community of microorganisms is known as the periphyton. The periphyton and natural chemical processes are responsible for approximately 90 percent of pollutant removal and waste breakdown. The plants remove about seven to ten percent of pollutants, and act as a carbon source for the microbes when they decay. Different species of aquatic plants have different rates of heavy metal uptake, a consideration for plant selection in a constructed wetland used for water treatment. Constructed wetlands are of two basic types: subsurface flow and surface flow wetlands.

tilley_et_al_2014_schematic_of_the_vertical_flow_constructed_wetland

Above is an example Horizontal Subsurface Flow Constructed Wetland. Source: https://en.wikipedia.org/wiki/File:Tilley_et_al_2014_Schematic_of_the_Horizontal_Subsurface_Flow_Constructed_Wetland.jpg

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Above is an example of a Verticale Subsurface Flow Constructed Wetland. Source: https://en.wikipedia.org/wiki/Constructed_wetland#/media/File:Tilley_et_al_2014_Schematic_of_the_Vertical_Flow_Constructed_Wetland.jpg

How well does this connect to this weeks reading?

The concept of Constructed Wetlands connects very well to our reading. The following are some key connections:

An excellent use of innovative technologies.
Provides a long term water management plan.
Address both wastewater and stormwater concerns.
A great example of the ecosystem approach – not only are constructed wetlands providing an ecosystem service to the human population (waste control), but they also create additional oxygen producing plants and provide a habitat for local birds and wildlife.

References:

Canada Mortgage and Hoursing Corporation – “Constructed Wetlands” https://www.cmhc-schl.gc.ca/en/inpr/su/waho/waho_008.cfm

USA Environmental Protection Agency – “Constructed Wetlands” https://www.epa.gov/wetlands/constructed-wetland

Water Canada – “Constructed Wetlands: How Cold Can You Go?” http://watercanada.net/2009/constructed-wetlands/

School of Environment Sciences, University of Guelph – “Constructed Wetlands” http://www.ces.uoguelph.ca/water/NCR/ConstructedWetlands.pdf

October 17, 2016

IDP: The Integrated Design Process

The IDP was first used in the early 1990s, by Canada’s C-2000 program (program supporting advanced, energy-efficient commercial building design) and IDEAS Challenge competition (multi-unit residential buildings challenge) to describe a more holistic approach to building design. In profesional practice, IDP has a significant impact on the makeup and role-playing of the initial design team. The client takes a more active role than usual, the architect becomes a team leader rather than the sole form-giver, and the structural, mechanical and electrical engineers take on active roles at early design stages. The team includes an energy specialist (simulator) and possibly a bio-climatic engineer. Depending on the nature of the project, a series of additional consultants may also join the project team from the outset.

Some of the key advantages of the IDP are cited below:

Goal-driven with the primary goal being sustainability, but with explicit subsidiary goals, objectives and targets set as a means to get there.
Facilitated by someone whose primary role is not to produce the building design or parts of it, but to be accountable for the process of design.
Structured to deal with issues and decisions in the right order, to avoid locking in bad performance by making non-reversible decisions with incomplete input or information.
Clear decision-making for a clearly understood methodology for making decisions and resolving critical conflicts.
Inclusive—everyone, from the owner to the operator, has something critical to contribute to the design and everyone must be heard.
Collaborative so that the architect is not simply the form-giver, but more the leader of a broader team collaboration with additional active roles earlier in the process.
Holistic or systemic thinking with the intent of producing something where the whole is greater than the sum of the parts, and which may even be more economic.
Whole-building budget setting—allows financial trade-offs, so money is spent where it is most beneficial when a holistic solution is found.

Below is a graphic representation of the IDP Process:

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References:

http://www.nrcan.gc.ca/energy/efficiency/buildings/eenb/integrated-design-process/4047

http://iisbe.org/down/gbc2005/Other_presentations/IDP_overview.pdf

http://www.infrastructure.alberta.ca/content/doctype486/production/leed_pd_appendix_7a.pdf

October 12, 2016

MEASURES OF SUSTAINIBILITY APPLIED TO THE CIRS BUILDING AT UBC

MEASURE 1: Design & Innovation

CIRS is aimed at being a regenerative building whose existence will improve the quality of the environment. This building contributes to reducing the energy use and carbon emissions. The building sequesters more carbon than the construction and decommissioning of the building will produce overtime.

MEASURE 2: Regional/ Community Design

Roof of the building is designed to be a self sustaining ecosystem where the vegetation includes indigenous plants for local birds and insects.

MEASURE 3: Land use and site ecology

The area of land that CIRS is built on improves the quality of the surrounding environment. It cleans the water it receives, captures heat that would otherwise be emitted to the environment and harbours vegetation that enriches the surrounding ecosystem.

MEASURE 4: Bio-climatic Design

Much of the heating in CIRS comes from the ground and from the heat exhausts from the building next door. Significant amount of the ventilation is from wind and a large part of the electricity is from the sun. This is really a building that survives within the natural flows of the environment.

MEASURE 5: Light and Air

Building is oriented to make optimal use of the daylight received by the site. The higher location of the windows allows for deeper penetration of the daylight into the interior spaces of the building. Solar shades and spandrel panels help control the glare and heat gain from the sun.

MEASURE 6: Water Cycle

All the water used in the building comes from the rain and the water leaving the building is of a better quality than the rain that is received on the roof. CIRS cleans the quality of the water and achieves a net positive in terms of water quality.

MEASURE 7: Energy flows and future energy

Uses geo exchange and solar energy. Uses waste heat from the Earth and Ocean Sciences building next door and captures the energy that would other wise be emitted to the environment.

MEASURE 8: Materials and construction

Wood used for the main structure of the building sequesters 600 tonnes of carbon. This is more carbon than the emissions from all the other construction materials, construction processes and decommissioning and the end of the lifetime of the building.

MEASURE 9: Long life, loose fit

CIRS is designed with ecological, social and economic rationale. Not only does it aim to improve the quality of the environment overtime it also aims to improve the health of its occupant. Flexibility, modularity, adaptability and expandability principles were included in the design of CIRS to ensure that it can adapt to new uses and respond to future space configuration requirements without the need of expensive and wasteful renovations.

MEASURE 10: Collective wisdom and feedback loops

In many ways CIRS is a research project that is intended to identify which processes and techniques work well and which ones have more scope for improvement. Research and observations of the way the building functions and interacts with the environment are ongoing and this knowledge will be used to improve sustainable designs of buildings in the future.