The 2015 University of Oklahoma International WaTER Conference Greywater Treatment for Reuse by Sand Filtration: A Study on the Microbial and Physico-Chemical Analysis Mukta Singh Chandel Awadhesh Pratap University, Rewa (M.P.) INDIA CSIR-National Environmental Engineering Research Institute, NEERI, Nagpur INDIA
OUTLINE Introduction Aim and Objectives Parameters Grey water filtration Unit Results and Discussion Greywater reuse guidelines and policy issues Conclusion
INTRODUCTION Greywater is that part of domestic wastewater which is not passing through toilets: i.e. originating from bath tubs Showers hand wash basins washing machines automatic dish washers kitchen sinks floor drains
Aim and Objectives Aim To understand the pathogen content and organic pollution in greywater and to develop the treatment techniques Objectives To access the current knowledge of pathogens present in greywater Characterization of greywater filtration technique followed by disinfection method Disinfection by Copper Pots/ copper strips Essential oils Sodium Hypochlorite
Parameters
GREYWATER SOURCE The experiments were conducted at National Environmental Engineering Research Institute (NEERI), Nagpur. These samples were collected from 1. The main drains of showers from bathrooms of swimming pool located in National Environmental Engineering Research Institute (NEERI) colony, 2. Kitchens of NEERI colony (Institute Campus), 3. Western coalfield limited (WCL) Laundry and 4. Ajni Railway colony, Nagpur.
Greywater Filtration Unit for household Design parameters Filtration Unit Total Greywater generation = 500 L/Day Average Flow = 500/6 = 0.083 m 3 / Hr. Filtration rate = 0.1 0.2 m 3 /m 2 /hr. Number of compartments = 2-3 Media and Size (mm) = Sand and Gravels (5-10 mm, 10-20mm & 20-40 mm) Depth of Media (m) = 0.2-0.4 Filter Loading Rate L/Day/ m 2 = 100 Total height (m) = 3-4 Filter Surface Area (m 2 ) = 2.5
Quantitatively Water Usage for Domestic Activities (Data for Ahmadabad, Delhi, Hyderabad, Kanpur, Kolkata, Madurai and Mumbai in India) House cleaning 7% Drinking 4% Cooking 3% Other 2% Bathing 29% Washing utensils 16% Washing clothes 19% Toilet 20% Fraction of total water demand % Source: Grail Research (2009), www.grailreasearch.com
Results of Physicochemical parameters Source Ajni Rly. colony Kitchen greywater WCL Laundry Bathroom greywater Parameters Raw Treated Raw Treated Raw Treated Raw Treated ph 7.9 7.6 7.8 7.5 8.1 7.7 7.5 7.4 Conductivity (µs) 547 529 534 518 560 540 326 300 TDS (mg/l) 335 290 327 300 382 360 236 210 Turbidity (NTU) Salinity (mg/l) 154 32 130 28 135 30 40 5.4 190 174 166 152 185 162 164 148 BOD (mg/l) 220 130 186 100 60 20 110 30 COD (mg/l) 490 210 446 170 440 155 320 100 n = 15
Cont... The results of the greywater analysis experiments are described in the following and behaviour of each water quality determinant is reported. Removal efficiency (in %) of greywater filtration unit (for physico-chemical parameters) :- Parameters Ajni rly colony NEERI Kitchen WCL Laundry NEERI swimming pool Parameters R.E. (%) R.E. (%) R.E. (%) R.E. (%) Turbidity (NTU) 79 78 77 86 BOD (mg/l) 40 46 66 72 COD (mg/l) 57 62 65 69 R.E.(%) Removal efficiency in percentage
Disposal Standards of CPCB for Quality of Treated Wastewater Parameters on land for irrigation ph 5.5-9.0 Into inland surface waters Into public sewers 5.5-9.0 5.5-9.0 Conductivity (µs) - - - TDS (mg/l) 2100 2100 2100 Turbidity (NTU) - - - Salinity (mg/l) - - - BOD (mg/l) 100 30 350 COD (mg/l) - 250 - Treated greywater was within the recommended range set by Central Pollution Control Board (CPCB) and would therefore be suitable for irrigation.
Microbial reduction by filtration unit 70000 60000 FC E. coli Salmonella spp Shigella spp Vibrio spp 40000 35000 30000 FC E. coli Salmonella spp Shigella spp Vibrio spp CFU/100 ml 50000 40000 30000 CFU/100 ml 25000 20000 15000 20000 10000 10000 5000 0 Raw gw Treated gw Mixed Greywater (Ajni Railway colony) 0 Raw gw Kitchen Greywater Treated gw 70-76% reduction of pathogens were observed in treated greywater. 65-82% reduction of pathogens were observed in treated greywater 5000 4000 FC E. coli Salmonella spp Shigella spp Vibrio spp 4000 3500 3000 FC E. coli Salmonella spp Shigella spp Vibrio spp CFU/100 ml 3000 2000 CFU/100 ml 2500 2000 1500 1000 1000 500 0 Raw gw WCL Laundry Treated gw 0 Raw gw Treated gw Swimming pool - Bathroom 70-84% reduction of pathogens were observed in treated greywater 69-78% reduction of pathogens were observed in treated greywater
Disinfection Options Disinfection is the process of eliminating pathogenic organisms from water which is achieved by their inactivation in the water. Even though pathogenic microorganisms are the targets of disinfection, it is indicator bacteria that are most commonly used to assess the microbial quality of the disinfected effluent. A variety of possible disinfection options exist for urban waters with varying efficacies for pathogen elimination. Disinfection methods which have been used in this process are: 1. Copper pots and strips 2. Essential oils 3. Chlorine
DISCUSSION Copper pot is showing better results in comparison with copper strip. Two essential oil (E.O.) i.e. citronella and lemongrass have been used to reduce the microbial load in the treated greywater. Both E.O. Having antibacterial activity but based on the disinfection data 100% elimination of pathogen observed in bathroom greywater after 12 h of contact time by using lemongrass oil whereas in case of citronella oil the effective contact time is 24 h. Chlorination was performed by adding hypochlorite solution (4%) to the sample in various concentrations at room temperature. In the experiment hypochlorite doses were set to satisfy a chlorine dose of 20 to 60 mg L -1 at the interval of 20mg L -1. Free chlorine was neutralized by adding sodium thiosulphate. In each of the above samples residual chlorine and microbial count were determined at the interval of 1h, 3h, 6h, 12h and 24h contact time.
Greywater reuse guidelines and policy issues There is very few information available about guidelines for greywater reuse, mostly because so far hardly any guidelines for greywater reuse exist. The World Health Organization (WHO, 1989) recommends that the wastewater for unrestricted irrigation should contain less than 1000/100 ml faecal coliform and less than one helminth egg/litre. It is noteworthy that the Indian Regulatory authorities do not have standards for these parameters, and hence the generators of greywater are free to discharge into public sewers, or on land or in rivers which will ultimately cause risks for pubic health. The discharge standards currently practiced have limits only on ph, TDS, and BOD, with standard for COD. It is necessary to make changes in policy regarding drafting new standards, and including the parameters like Faecal coliforms, E. coli, Salmonella, Shigella and Vibrio spp. in a new regulatory regime that would safeguard public health as a matter of priority.
Cost Analysis of Disinfection Methods Disinfections methods Price Total cost Amount Cu Pot/Strips 500/- ($ 7.61) 1pot Essential oils 300/- ($ 4.57) 100ml Sodium hypochlorite 5000/- ($ 76.11) 500ml There is no operational and maintenance cost for the essential oils and Cu strips. For sodium hypochlorite, it should be stored at temperature below 29ºC in a corrosion-resistant tank.
Conclusion It was observed that simple filtration system reduced the BOD and COD significantly with the removal efficiency of 40% and 57% in Ajni greywater, 46 & 62% in kitchen GW, 66 & 65 % in laundry GW and 72 & 69 % in swimming pool GW and meeting with the CPCB standards set for treated wastewater but not able to remove 100% pathogen. Further there is significant reduction has been observed by using Lemongrass oil and copper strips. For ex. In mixed greywater the removal efficiency of all 5 pathogens have been observed from 80 to 98% by using Cit. oil whereas by using LG it was 98 to 100%. sodium hypochlorite were also shown to be effective disinfectant (96-100% R.E.) These results highlight the need for extensive microbiological monitoring of greywater systems as well as the need for the development of greywater standards, which are currently non-existent in developing countries such as India.
Acknowledgment Dr. Pawan Labhasetwar, NEERI, India Dr. Mukul Kulshrestha, Maulana Azad National Institute of Technology, Bhopal, India. Dr. Arpita Awasthi, TRS College, Rewa, India Sandeep Narnaware, NEERI, India University of Oklahoma My Family and friends
Mukta Singh - mktsingh90@gmail.com Arpita Awasthi - arpitaawasthi@ymail.com Mukul Kulshrestha - mukul_kuls@yahoo.com Pawan Labhasetwar - pk_labhasetwar@neeri.res.in