Constructed wetlands

 

Thesis

The landscape and building function as a single integrated, net zero water system, which is designed to collect and store rainwater, clean and re-use waste water produced by the building or its occupants.

 

Hypothesis

The idea that it’s always raining in London is one of the world’s biggest myths about the city. Per head of population, London actually has less rainfall than just about anywhere in the world and even in absolute terms (total rainfall). Despite its reputation as being a rainy city, London receives less precipitation (with 601 mm in a year), than Rome (at 834 mm),  Bordeaux (at 923 mm), Toulouse (at 668 mm ), and Naples (at 1,006 mm per year).

 

London is facing a growing water shortage as the population grows towards ten million, expected to expand by 700,000 over the next 10 years (the Greater London Urban Area currently sits at 8.3 million).

Unless action is taken, the deficit will be two per cent, or 125 million litres a day by 2020, according to Thames Water’s draft long-term strategy 2015-2040, rising to 16 per cent by 2040 or 367 million litres per day which is the need of 2.2 million customers.

Thames Water is now even investigating recycling waste water including from dishwashers, washing machines, baths and toilets to turn into drinking water. Also London has become the first city in Britain to install a desalination plant which is a facility normally found in deserts that converts salty seawater into drinkable freshwater and most of the time it’s planned to keep it switched off, because desalination requires almost  twice as much as energy than a conventional water treatment plant.

After 2025 we are likely to require a major new source of water, either by building a large new reservoir or a major water transfer scheme from elsewhere in the country, or significant re-use of wastewater.

Wetlands have great capability of naturally improving water quality.

Over the past 1000 years, wetland habitats have been drained, developed on or polluted leading to a 90% loss of wetland area. Over the past 50 years, more than 100,000 wetland archaeological sites have also been damaged or lost since the Industrial Revolution. As a consequence of habitat loss, wildlife and ecosystem services have declined or been lost. The majority of fragmented and diminished wetlands currently within the UK’s are also in poor condition.

Wetlands can be constructed in strategic locations to clean up rivers while producing enough biomass to serve as a clean energy source. It has a role in providing water quality protection in the catchment by filtering pollutants such as sediments, nutrients, organic and inorganic matter and bacteria where as sewage treatment plants utilizes a combination of biological, chemical and mechanical processes.

 

Methodology

 

The landscape and building will perform as a single integrated with net zero water system by injecting an idea of to “Produce – Use – Store – Share”.

 

Rainwater Collection

- Rainwater is channeled to a constructed wetland

- Rainwater aerated by waterfalls

- Enters pond

- Overflow from pond feeds rain garden

- Rain garden recharges aquifer

- 100% of wastewater is reused in the building

 

Wastewater Reuse

- Wastewater first enters a treatment tank for anaerobic breakdown of solids

- Wastewater goes through the terraced (gravity-fed) constructed wetlands where

microorganisms break down contaminants in the water.

- Filtered wastewater reenters the building and is disinfected via UV light

- Water is reused for flushing toilets and cooling

- Supply neighboring architecture when necessary

 

Design criteria

 

Ordinary constructed wetlands only perform horizontally, upstream to downstream, but the design will challenge to act vertically and to float to take its full potential, capability and ability.

 

Expected outcome/impact

By introducing natural way ”The constructed wetlands” and wastewater reuse program could not only provide natural water balance in the landscape and help to provide protection against floods, but also air pollution, groundwater recharge, preservation of biodiversity and habitat, and improved living standards of local residents.

Also constructed wetlands could possibly lock away huge amounts of carbon(wetland regeneration could save about 400,000 tonnes of carbon a year), provide havens for wildlife and fantastic places for people to live, visit and enjoy

 

 

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