EMSC 5103 : Sustainable ConstructionWater and wastewater management

Water and wastewater/sewage management Objective Sustainable water management is to ensure efficient usage of water and minimize

pollution

Treated water

Water after going through treatment enters a building as purified water but leaves as sewage. • Treatment of raw water into purified water requires energy and money. Efficient usage ensure less energy wastage hence less energy demand thus less GHG emission. •The transmission of treated water to consumer site requires infrastructure, storage and energy (i.e pump) to deliver.

After usage, the treated water becomes wastewater which will affect our environment ecology, wastewater treatment and indirectly energy consumption.

Hence, efficient usage of water and proper purification of sewage can save energy and reduce GHG emission. Putting water and wastewater treatment consideration in design stage will provide opportunity to conserve water usage.

EMSC 5103 : Sustainable Construction

Water treatment processes :

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Water treatment process:Objective To provide potable, safe and ample treated water for consumption:

residential, commercial, institutional and industry. Must fulfill drinking water standard.

Raw water intake Source of raw water: river, lake. Provide coarse and fine screen at intake point

Pretreatment Settling tank at water treatment plant; functions as settling tank and also storage facility.

Coagulation and flocculation

Adding chemical e.g. aluminum sulfate to coagulate suspended solids; forming of flocs,

Sedimentation Provide settling tank for flocs to settle via rectangular or circular tank or inclined plate settlers

Filtration Using sand filter to remove fine flocs

Disinfection Using chlorine to disinfect – excessive will produce by products such as chloroform

pH adjustment & fluoride addition

pH adjustment to increase pH to neutral point and add fluoride .

EMSC 5103 : Sustainable Construction

Water treatment processes:

EMSC 5103 : Sustainable Construction

Sewage treatment processes:

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Wastewater/sewage treatment process:Objective To remove pollutants from domestic and commercial and institutional

sewage to a level that is safe to discharge into a river/sea. Must fulfill effluent standard.

Source of sewage Residential, hotels, commercial centers,

Preliminary treatment Screening, grit removal, grease removal

Primary treatment Allows settleable solid to settle via “primary settling tank” either circular or rctangular

Secondary treatment Allow the microorganism to digest the organic waste.•Provide aeration system for microbes to digest the waste•Provide secondary settling tank to settle out the microbes

Advance treatment Removal of nutrients: nitrate and phosphate from treated effluent and disinfection before disposal

Sludge treatment and disposal

Settled solids from primary and secondary settling tanks require further treatment. It consists of concentration, dewatering, drying. Potential to generate biogas from concentrated sludge and biomass from dried sludge.

EMSC 5103 : Sustainable Construction

EMSC 5103 : Sustainable ConstructionWater and wastewater managementMain considerations during design stage

Conservation Use water more efficient to reduce wastage

Delight Use water to create a dynamic energy and around buildings – supporting biodiversity

Pollution Minimize organic waste to landfill – by reducing the sludge from sewage treatment process.

Rainwater drainage

Minimize the impact of the built environment on the flow if of rainwater back into the natural environment

Environmental impacts

Consider benefit of water savings measure or sewage treatment options that minimize environmental impact

Education Enviornmental benefits from educating public

Closing the circle

Consider using the waste from one rpocess as inout for another

Economics Sustainable economic look into the life cycle cost of desing measure which sometime able to present cheaper cost.

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Conservation

Via efficient water system such as half/full flush toilet, Reuse of grey water or collection of rain on-site for non-potable uses such as gardening and toilet flushing can also saved metered water. Over abstraction of ground water will depletes groundwater supplies and reduces surface water flows

Water conservation associated with energy savings. Financial savings are generally modest except for industrial processes or major leakage

Examples : 4-litres WCs, vacuum and dry toilets (flights), low flow shower heads or pipes,

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Delight

Water features are increasingly seen as an intrinsic part of the approach to the built environment It facilitates play and enhance biodiversity .

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Pollution

While many pollutants such as lead, nitrates, aluminum originates from industrial discharges and agricultural practice, there is also a great deal where the building designer and user can have a positive influence including reducing pollution from rainwater runoff, leachate from buildings and landscape elements, landfill and water borne waste. Rainwater drainage

Stormwater runoff presents high peak flow problem due to more impervious surfaces at roof, walkway, parking etc. Sustainable drainage system SuDS, aims at control flooding; prevent pollution, recharge groundwater and reduce load to sewage treatment plants. Typical system are swale, permeable surfaces, filter strips.

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Environmental impacts

There should be an assessment of the relative environmental impact that are being traded (i.e available in the market) . For example: effluent quality Vs, energy input or treatment size; water saving from domestic greywater system vs. energy and chemical use. Sustainable sewage treatment requires attention to the capacity of the receiving environment. Education

Water management requires better understanding of the closed circle inherent in natural systems. Good design and management education should concentrate on developing an appreciation and understanding of where water comes from and where you discharge them after use,

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Wetland as sewage treatment option

EMSC 5103 : Sustainable ConstructionWater and wastewater management

Water saving features

Construction players can think about the feasibility of utilizing renewable energy source for new project.