LIVING BUILDING
SERIES
Q & A of Living Building Series
Near Zero Dialog #04.
Near Zero Water: Design Approaches for Buildings
Presenter: Rajesh Jain. Wappsys. Gurgaon
Responses to questions from the Master Speaker of the April 30, 2020 presentation.
All that you wanted to know on Near Zero water design approaches for buildings. GreeKnow brings you insights and directions to solutions from experts. You’re welcome to mail contact@premjainmemorialtrust.com for help. This is a listing of questions raised in the Living Building Series of online classes. This will make for more useful reading if you have watched the E Series of April30, 2020. The questions [and responses from experts] are listed in no order of priority and are drawn from the conversation featured in that episode.
Mail us at contact@premjainmemorialtrust.com for more, or at . Mail us at AltTech555@gmail.com.
Q from Purushothama C.T: Fixing water meter for all houses should be compulsory. During the scarcity of water, the summer season should be very strict in the consumption of water. if the usage of water exceeds beyond the required quantity should be imposed with high fine with warning.
A. There is a significant water consumption reduction in houses/ apartments after implementation of metering and billing. Upto 20-35% is reported. Bangalore and Hyderabad have taken a lead in this area. Metering is always linked to pricing and billing. One can have different slabs with different rates in different seasons depending on water availability or water cost. We agree that this should be made compulsory at the constriction stage and must be retrofitted in existing buildings and societies.
Q from V Ajay: We India are exporting many products to other countries, products that use a large amount of water to manufacture. One orange needs many liters of water to grow, but when we export these oranges we are not adding the cost of water that is used to grow these, resulting in a huge loss in the Indian economy as well farmers, only certain traders and countries get benefit out of it.
My suggestions are
• why can't we stop growing crops that need so much water to grow as many other countries already did?
• instead we can grow crops that require not much water and export it?
• we can also manage the used water in Agriculture land and industries back in usage?"
A. There is a term for this. It is called virtual water trade. We need to evolve very strongly in this area by promoting the right policies, subsidies and MSP support system. We need to find a mechanism where water and power are not subsidized to the farmers and they are paid higher prices for the crops. We also need to identify crops which are suitable for Indian climate, less water intensive and there is a export market for the same. We also agree with your suggestion that water intensive crops should only be allowed during rainy season or with wastewater recycling.
Q from Kamlesh Mahajan: Is STP treated water can be used for thermal power plant?
A. Yes, Treated Water can be used for Thermal Power Plant. As per the notification of the Ministry of Power (Government of India), under clause 6.2(5) of their Tariff Policy dated 28.01.2016 has stipulated that the Thermal Power Plants located within 50 Km radius of sewage treatment plant of Municipality / Local bodies/ similar organization to use Treated Wastewater.
Q from Karthik P: Is there any source that is collating data on improvement of water quality in lakes, rivers during this lockdown? Kindly share.
A. CPCB is doing online monitoring of Water quality of rivers at specific regions.
Q from Umesh Rao: where water supplies to apartments are tanker water, all citizens use RO system for filtering water, where 50 percent is drained out, what is the solution to this?
A. RO is already banned to be used at homes if TDS is less than 500 pm. When TDS is more, it is better to have a centralized RO to recover the reject and find its usage or implement zero discharge schemes with RWH to manage without individual ROs.
Q from Neha Vyas: What can be done with RO reject water? Can it be reused?
A. Depending on the TDS and hardness of the RO reject, we can use it for house mopping, horticulture and flushing toilets.
Q from Umesh Rao: is it possible to adopt metering to existing apartment complexes and make it mandatory?
A. It is being done in many complexes in Bangalore and Hyderabad. It should be made mandatory.
Q from Karthik P: Currently we have more treated water than can be reused with a project. One issue is because regulation currently doesn't allow for portability of treated water. How can we have this regulation changed so % of usage of treated water goes up? Will result in higher adoption...?
A. There is no such regulation.
Q from Mohamed Abubacker: What is ZLD?
A. Zero liquid discharge. When we treat and recover all the wastewater for reuse, we achieve Zld.
Q from Sunil Nandipati: Can we make the Net Zero water during pre-construction and on-site construction. Will it be able to reduce the water demand for construction?
A. Lot of cities are stipulating treated wastewater to be used for construction. Construction sites are also required to have onsite STPs for labor camps to treat and reuse the wastewater.
Q from Sunil Agrawal: There is stigma in using grey and black treated and recycled water. How people should be convinced to bring them on board?
A. More and more case studies will convert people, online monitoring of water quality data etc. In the worst case, segregate sewage into black and grey can be practiced and greywater (70-80%) can be converted into drinking water
Q from NR Ashok: Flushing bio waste takes up a lot of water. Can we think of using a special coating on toilets which will slide the bio waste (using almost no water) into a special very low friction smooth pipe and the waste gets into a tank which we can treat much more easily?
A. Waterless urinals and vacuum toilets can be used to save water. This is what we know of to save water. There are some dry Indian toilets concepts too to save water.
Q from Karthik p: With the corona virus now found in waste water, recycling solutions will have a harder time unless the solutions can show that it removes the virus also. Do the current waste water treatment solutions do this? Which solutions can we suggest?
A. The current water systems are using various methods like chlorination, UV treatment, etc. to remove any kind of microbial pathogens. Chlorine if used in the right quantity, it's not hazardous and useful to kill the virus and to stop the water transmission. It is also a slightly cheap method. Ultraviolet radiation also helps to remove the viruses.
Q from Yusuf Turab: Is there any restrictions from CPCB with regards to the use of bio-remediation techniques like DWWTs, REED bed etc?
A. No, there is no restriction from CPCB.
Q from Karthik p: Are there traditionally treatment methods for high salinity or high tds?
A. Various research stated that Neem leaves, Vettiver root, Thulsi leaves and Lemon peel can be used to reduce the TDS and salinity of water.
Q from Mohan Iyer: What is the estimated evaporation and blowdown loss in cooling towers? Can we have a thumb rule of water loss per TR of cooling? What is the approach of health grade water treatment as compared to standard waste water treatment for drinking water?
A. The estimated evaporation is 5.5 to 7 L /TR and blow down is 1-2 L. Yes, as a thumb rule we can consider 10 L of water loss/Tr.
Q from Tushar Parikh: Is more and more use of detergents and chemical in washing and cleaning effecting the sewage bio degradation? What does it do the he STP plants ...is the organic washing material the way forward?
A. It only increases the COD of the wastewater. Yes, organic washing material is way forward.
Q from Mohamed Abubacker: What is the difference between black and grey water?
A. Greywater is the result of water being used for household purposes, like cleaning and washing clothes, while black water contains faeces and urine and other bodily wastes.
Q from Suhail Rahman: When you reduced 230KLD to 39KLD fresh water requirement, did it also include health grade level recycling?
A. Yes
Q from Devaraj Reddy: Can you explain detail of official building LPCD. What is the Govt norm and how much one can achieve?
A. The water consumption norm in an Office Building as per CPHEEO/IS codes is 45 LPCD. If we completely recycle treated water, we can reduce 50-70 % of LPCD in an office building.
Q from Suhail Rahman: Can you elaborate on methods of health grade recycling? is it RO? Are there any other more efficient technologies available?
A. It is a combination of media filtration, UF, Ozonation, RO and UV.
Q from NR Ashok: Rain water storage sump of very large capacity should be made compulsory. Only then rain water can be stored and used for a longer periods. Flow meters should be made compulsory. Why should people who use less water be made to pay for more water used by others?
A. Fixing water meter at each household level is a good idea and it will help to reduce the wastage of water. These meters provide metrics to monitor water usage of each apartment and accordingly they are charged. Apartment Complexes report around a 20-30% reduction in water consumption after implementing water metering.
Q from Gayathri Aaditya Ghatty: Is there a way to detect water leakages in buildings?
A. Wireless water leak detectors and Cloud-based sensors are very helpful to detect leakages in buildings
Q from Haarika Reddy K: What could be safe alternatives of using RO systems for treating water?
A. There are many variants of RO technology, ion exchange and electro-chemical processes.
Q from Tushar Parikh: Is softener water good for bathing with this big amount of salt going into it?
A. I doubt that anyone can absorb a significant amount of sodium through skin and bathing. In my point of view, we can use soft water for bathing but not for drinking.
Q from Komal Gilda: What is SBT in green technology, shown in overview of technology?
A. The technology is based on a bio-conversion process where fundamental reactions of nature, namely respiration, photosynthesis & mineral weathering take place in a media housing micro & macro-organism which bring about the desired purification.
Q from Krishna Patel: Can the rain water collected from roof tops, be directed to the nearby reservoir, instead of making storages?
A. Yes
Q from Madhav Kamat: How effective is Phytorid system?
A. Phytorid Technology System are effective in treating BOD,TSS, N and P as well as for reducing metals, organic pollutants, and pathogens, pretreatment. It takes a large area and requires pretreatment
Q from Mohamed Abubacker: How can we avoid/ reduce the excess drain from STP?
A. By treating wastewater to health grade standards and reusing it for meeting the demand of cooling tower, firefighting, flushing, horticulture, car washing and even for potable use.
Q from Gayathri Aaditya Ghatty: Like the energy payback….. do we have way to measure the water treatment payback?
A. Yes. Fresh water costing Rs. 150 per cum and treated wastewater costing Rs. 50 per cum, will definitely give an ROI against a certain investment.
Q from Dr. Prakash Kulkarni: NGT order is unrealsitic For ex. Phosphorous 2 mg/ lit.?
A. No, NGT orders are not unrealistic; .Global standards for phosphorus are even more stringent. Over the time norms will become stricter. Phosphorus are responsible for eutrophication in water bodies which can lead to the mortality of fish and plants due to lack of oxygen and light. This limit is achievable; various technologies in the world are able to reduce the Phosphorus to less than 2 mg/l.
Q from Niranjan Khatri: Water conservation starts with me tell them about small/large peg of water leading to scarcity value of water?
A. Agreed
Q from Purushothama C.T: How to maintain quality of harvested water for long time? some mosquitos breed in fresh water also.?
A. Wind-blown dirt, leaves, faecal droppings from birds and animals, insects and contaminated litter on the catchment areas can be sources of contamination of rainwater, leading to health risks from the consumption of contaminated water from storage tanks.
Gutter guards, porous/ nonporous flexible covers etc. can prevent the mosquito breeding in a storage tank.
Cleaning of roof, gutter, downpipes etc. is also important to reduce the chances of breeding and filtration and disinfection before use will be important.
Q from Mohan Iyer: Would it be easy to capture the condensate from the evaporator cooling coil for portable purposes with minor treatment and caution?
A. Yes, condensate can be easily captured from the evaporator. Condensate is considered good water — as pure as distilled water, low in mineral content, and can be used for several applications in addition to cooling towers. It can be mineralized for drinking purpose too.
Q from Anuprasad sg: Is it possible to bottle rain water? How to treat it clean?
A. Filter like carbon, ceramic, and membrane filters with pore sizes of less than 1 micron can remove most pathogens in pretreatment. After that, it will go for ozonation and UV treatment in the final stage before Bottling.
Q from Sravani Kandula: What will be the cost for treating of one liter waste water and what will the price to utilize that treated water?
A. It will totally depend on the plant capacity. For large plants, it can be as low as 5 paise or less per LTR.
Q from Rakesh Bansal: A question more relevant for policymakers - Most of the existing buildings (esp plotted ones) do not have any space for building tanks for RWH. Same is applicable for building a groundwater sump for waste water storage so that it can then be pumped to a treatment plant somewhere on the terrace. Is it possible to convince the Municipal corporations to allow building the tanks outside the building, purely for these purposes. This will make it viable to retrofit the buildings with recycling plant and RWH system.
A. Sure
Q from Anuprasad SG- from Kozhikode: I am from Kerala. We are planning for a startup to bottle rain water before reaching ground. Please provide your advice and methods for treatment and capture before bottling.
A. Filter like carbon, ceramic, and membrane filters with pore sizes of less than 1 micron can remove most pathogens in pretreatment. After that, it will go for ozonation and UV treatment in the final stage before bottling.