S.Vishwanath is  a Civil Engineer and an Urban Planner by qualification. He has 30 years of experience in the water, waste-water and sanitation sector. He is an Adjunct Professor and teaches a course on Water at the Azeem Premji University, Bangalore. He writes a regular column called Waterwise in the national newspaper The Hindu. He is an Advisor to Arghyam a funding agency and to Biome Trust which implements sustainable water and sanitation systems in schools. He has been in the policy writing space on Rainwater harvesting, Faecal Sludge management and waste-water reuse for the Government of Karnataka, India.

Managing water and waste streams in a building - Lessons in decentralisation

Seminar

Water in the circular economy: Opportunities and challenges

Highlights

Water management,urban,technology,storage,sanitation

Keywords

Urban

Introduction and objectives

Running an ecological design practice provides an opportunity to include management of water and waste-water in individual buildings and institutions we design.

In the context of Bengaluru,where at a city level water has become a scarce resource,it is possible to easily integrate rainwater harvesting , greywater recycling, kitchen waste composting, and terrace gardening into individual homes and institutional buildings such as schools to reduce dependency on external water and sanitation systems. Not only is harvested rainwater a major supplement but the nutrients from ecosan and greywater can be used productively for food production at household level.

Methodology approach

Designing of building often avoids services such as water and wastewater infrastructure assuming a link to the city lines. More often than not buildings in the periphery of a growing city have to create independent services such as a borewell for water supply and septic tanks for sanitation systems.Analysing rainfall pattern both storage and recharge systems were designed to hold and reuse rainwater. Grey water tanks were located to catch clothes wash and bath water and filtered using biological systems for reuse in toilet flushing and for vegetable cultivation. Ecosan toilets provided urine and dessicated faeces as fertiliser for crops.

Analysis and results

In the design of a large school building it was possible to capture almost all the rainwater falling in a large sump tank. This water is filtered before being used for drinking. For toilets it is used directly. Greywater treatment system recycle water for flushing requirement. The school with 200 students is independent of the city system for water and wastewater management.

In most houses depending on the rooftop area between 100,000 to 200,000 litres of rainwater is harvested annually.Where a perched aquifer exists an open well provides all the water requirement of the house and is recharged using rooftop rainwater. Greywater systems recycle almost all shower and washing machine water. By replacing detergents with ecofriendly soaps it is possible to simplify treatment requirements. Twin leach pit toilets and ecosan toilets provide safe containment and reuse of faeces.This in turn is reused for growing rooftop vegetable gardens. Kitchen waste is composted and reused on site. A rooftop provides an ideal space for reusing greywater and nutrients from human waste as also to harvest rain. About 40 sq. mt. of roof area can provide water, food and energy security and also take care of waste from a house in Bengaluru.

Conclusions and recommendations

By designing for rainwater harvesting,water efficient fixtures,recycling systems, ecosan toilets it is possible to supplement water requirements to a great extent and complete the food cycle using nutrients from human and kitchen waste.Ecological design is the way forward in closing the water and nutrient loop.Architects and engineers can play a crucial role in addressing the water and wastewater management of cities Simple design tools and filters for rainwater and grey water recycling is needed to help take the design implementation forward. Building bye-laws and tax incentives can be thought of appropriately for each city to to encourage such designs .

Presenting author; Mr. Vishwanath Srikantaiah, Sustainable Sanitation Alliance (Biome Environmental Trust), India

www.bwssb.org

http://www.thehindu.com/life-and-style/homes-and-gardens/the-citys-future/article19474412.ece

bengaluru.urbanwaters.in