(Print), ISSN (Online) Volume 3, Issue 2, July- December (2012), IAEME TECHNOLOGY (IJCIET)

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1 INTERNATIONAL International Journal of Civil JOURNAL Engineering and OF Technology CIVIL (IJCIET), ENGINEERING ISSN AND TECHNOLOGY (IJCIET) ISSN (Print) ISSN (Online) Volume 3, Issue 2, July- December (2012), pp IAEME: Journal Impact Factor (2011): (Calculated by GISI) IJCIET I A E M E WASTEWATER MANAGEMENT IN A DWELLING HOUSE- A CASE STUDY Dr. P. Mariappan, M.E., Ph.D.,* *TWAD Board, 6A,Balasubramanian Nagar, Rajakkapatti, Dindigul-4, TN mars_pm@yahoo.com. ABSTRACT Domestic wastewater treatment system for a dwelling house, grey water treatment using planter bed and septic tank with root zone bed (RZB) for black water, has been experimented in a house as a zero discharge concept. Two years of operation and maintenance suggests that model is efficient for pollutant removal. System is maintenance free and economically viable for individual houses in rural areas as well in semi-urban developing areas. Installation cost is about 0.1% of cost construction of house. Providing zero discharge concepts may be made mandatory to ease the burden on the government and to keep environment safe. INTRODUCTION Population explosion coupled with urbanization leads to increase in water utilization and wastewater generation from human settlements. As per law of conservation of mass, more than 80 % water supplied for drinking purposes turns into wastewater posing a big task to the public health Engineers to handle. Further more, disposal of untreated wastewater pollutes the fresh water sources too. There are 13 major cities and 12 minor towns along the river course of Cauvery River. Some cities have insufficient capacity of wastewater treatment plants and some do not have proper drainage schemes. As result, pollution of river water takes owing to discharge of untreated wastewater into the river course. In India, it is estimated that more than 8642 X 10 6 m 3 of wastewater is generated per annum from 212 class I cities and 241 class II towns. Only 23 % of the wastewater is being treated mostly at primary level prior to disposal, and remaining 77 % untreated water is discharged into surface water bodies and on land sans proper treatment. Mostly, wastewater flowing along the streets is common in the developing semi urban areas. It takes time the drainage facilities to come. Dwindling of water sources day by day and pollution of fresh water points are the two problems generally encountered in the water and sanitation sectors. A single solution to the problem would be the Zero Discharge. Recently, Industries are forced to adopt 16

2 the above strategy. But, it is equally necessary to go for the residential houses. The present report details the zero discharge principle adopted in a dwelling house and the performance is also presented for the replication of the model for the clean world. Domestic wastewater Wastewater generated from a dwelling house shall be classified into Grey water (Sullage) and Black water. Greywater is the one generated from bath, kitchen and washing ( non-toilet plumbing fixtures such as showers, basins and taps). Toilet water is generally called 'blackwater' or 'sewage'. Grey water contains far lesser nitrogen than black water Nine-tenths of the nitrogen contained in combined wastewater derived from toilet wastes (i.e., from the black water). Nitrogen is one of the most serious and difficultto-remove pollutants affecting our potential drinking water supply. Grey water contains far fewer pathogens and plant nutrients ( N, P and K ) than black water ( Ottoson & Stenstrom,2003; Frielder, 2004; Jefferson et al, 2004). Medical and public health professionals view feces as the most significant source of human pathogens. Keeping toilet wastes out of the wastewater stream dramatically reduces the danger of spreading such organisms via water. Grey water decomposes much faster than black water. The implication of the more rapid decomposition of grey water pollutants is the quicker stabilization and therefore enhanced prevention of water pollution. Sources of wastewater from a dwelling house with type and quantity per head per day are tabulated ( Table 1). Table 1.Sources of wastewater and its type ( GOI,DDWS,2008) No. Source of wastewater Types of wastewater Quantity/ person 1 Toilets Black water 3 liters 2 Bathing Grey water liters 3 Kitchen Grey water 5-10 liters 4 Washing cloth Grey water liters 5 Animals Grey water liters day/ From the analysis of the source of wastewater and its types, it is revealed that more than 90 percent of waste water generated is grey water. Therefore, grey water management is a major challenge in rural in the country. Water management may involve reuse/ recycling of water after appropriate treatment for a variety of purposes including irrigation, domestic purposes and toilet flushing. For effective management of water in rural areas, focus should be on management at household level. Various international agencies have come up with guidelines for grey water reuse. International guidelines (NRMMC, 2006, WHO, 2006 ) set limits for specific parameters for grey water and WHO (2006) recommends as monitoring value for : 17

3 a) Restricted irrigation: < 1 helminth egg/l and <10 3 per 100 ml. E.Coli due to its potential for regrowth; relaxed to < 10 6 E.Coli when exposure is limited or regrowth is likely low. b) Unrestricted irrigation: < 1 helminth egg/l and < 10 3 E.Coli per 100 ml, relaxed to < 10 4 for high growing leaf crops or drip irrigation. ACTC (2008) recommends: a) Sub-surface irrigation ( mm below ground level and sub-soil irrigation ( > 300 mm below ground level) to treat grey water to a quality of 20 mg/l of BOD 5, 30 mg/l TSS. b) For covered surface drip irrigation, surface irrigation, toilet flushing, laundry use and car washing to treat and disinfect grey water to a quality of 20 mg/l of BOD 5, 30 mg/l TSS and 10 CPU of thermotolerant coliforms/100 ml.. Godfrey et al ( 2010) have attempted to focus on grey water reuse component that recovers water from hand washing and bathing to be treated and reused for toilet flushing and for kitchen garden irrigation at six selected schools in Madhya Pradesh. The greywater systems were designed in the following stages: Absorption : soap suds and hair are adsorbed onto a synthetic sponge in the ion; first chamber, Sedimentation: solids are settled in a baffled settling in the second chamber, Filtration; water is filtered at 0.2 m3/m2 h ( 2000 L/day) through a bed of gravel ( ) mm and fine gravel ( 6-10 ) mm in the third and fourth chamber, Aeration: filtered water is aerated by gravity through a step tank and then Chlorination: water is stored in a chamber where it is chlorinated twice per week. Gikas and Tsihrintzis ( 2010) have studied the efficiency of Constructed wetland systems (CWs). Root zone bed/ Constructed wet lands for on-site treatment of domestic wastewater in North Greece. For wastewater treatment are efficient pollutant removal, and simple and low cost in operation. They are used in many countries of Europe, not only for the service of small settlements but also of single houses. CWs are presented as an alternative solution for domestic wastewater treatment in agricultural areas, where there is no possibility of residence connection to a public sewer and a wastewater treatment system. They are an ideal solution for onsite wastewater treatment of rural houses or resorts, such as small hotels, hostels etc. many of these systems that usually serve 4 persons have been built in recent years in the Czech republic. They consist of a septic tank followed by a horizontal subsurface flow (HSF) CW, with a surface area of square metre; they are planted with various plants such as phragmites australis, phalaris arundinacea etc. In germany, about 3000 such HSF CW operate today, most of them designed for 5 person equivalent with a mean area of 30 square metre. In Denmark, small scale CWs have been used since in all cases, a pretreatment stage of two or three settling tanks is used, which receives the wastewater before it enters the wetland. The unit surface area of the CW is 3-5 square metre. Plants commonly used include typha latifolia or typha augustifolia, phragmaties australis. Zeoloite has been used in wastewater treatment for further removal of phosphorus and ammonia, aiming at improving the effluent quality. The main zeolite property explained in wastewater treatment processes I the 18

4 ammonium cation ( NH4+) exchange ability. Liu and Lo ( 2001 ) summarized the advantages of using natural zeolite in ammonia removal from wastewater, which include i. Increase in ammonia uptake and/or its transformation to gaseous nitrogen through oxidation; ii. Satisfaction of removal efficiencies even at low temperatures; iii. Low cost compared to other materials; and iv. Small size and easier maintenance of treatment facilities. Zeoloite has been used in CWs. Primary applications include the use as substrate inside the wetlands, as pretreatment systems before the wastewater input and as an appropriate filter media for further treatment of CW effluent. MATERIALS AND METHODS Facility description Zero discharge wastewater treatment with reuse system is in operation since July 2009 in a dwelling house at 6A, Balasubramanian Nagar, Rajakkapatti, Dindigul, TN. The house accommodates two families having 3 people in each family. Daily 600 litres of water is being pumped from a borewell by means of 5.0 HP motor coupled with air compressor and stored in 2 numbers of 300 litres sintex tanks placed on roof. As mixing of black water and grey water makes the treatment a little complex, greywater and black water are collected separately with separate plumbing arrangement as shown in the flow diagram given below. Kitchen Bath room Washing Grey Water Treatment Gardening/ groundwater recharge Toilet Septic tank CW Gardening / Recharge Figure 1 Flow diagram showing the wastewater collection, treatment and reuse The dimensions of various process units in the black water treatment and graywater handling systems are presented in figure 2a and 2b Gravel Packed Receiving chamber Planter bed 40 mm HBS for 30 cm, 20 mm HBS-15 cm, Soil-15 cm Planter bed 40 mm HBS for 30 cm, 20 mm HBS-15 cm, Soil-15 cm Sand filter Figure 2a. Cross section of Planter Bed ( Soil Box planter) 19

5 90 cm 4.25 m Figure 2b. Plan of planter box The photographic image of the planter bed shown below ( Photo 1) Photo 1. Planter bed (Soil Box planter) The black water treatment system accommodates septic tank and a sub surface Constructed wet land (CW) ( reed bed /root zone bed). The size of the septic tank is 3.0 m X 2.40 m. Constructed wet land has the size of 3.5 m X 0.45 m X 0.60 m with receiving chamber and outlet box. Wastewater generated from the toilets is passed through Septic tank and CW. The overflow of the septic tank is connected to the on-site CW. Water quality monitoring The planter bed for grey water treatment and constructed wet land for treating septic tank effluent has been in operation and operation since july In order to assess the function and pollutant removal efficiency of the facility, wastewater samples were collected periodically from the influent and the effluent of planter box and CW. TSS, BOD, COD and faecal coliform were analysed as per Standard methods. RESULTS AND DISCUSSION 20

6 Pollutant parameter variation along the facility Planter bed Periodically measured pollutant parameters at the inlet and outlet of planter bed are presented in table 2. Mean BOD, COD and TSS influent concentrations, during the monitoring period, were 87 mg/l, 112 mg/l, and 59 mg/l respectively. These concentrations decreased along the planter bed, indicating that organic matter removal is achieved. Variation in organic concentration in the grey water generated is observed, which infers that the quality of grey water demands on cooking menu, washing pattern and bathing too. It agrees with the pattern reported by Gikas and Tsihrintzis (2010). Table 2.Removal characteristics of Grey water treatment system Pollutant parameter variation along the planter bed Sl.No Parameters Mean Minimum Maximum 1 BOD (mg/l) influent Effluent Efficiency (%) COD (mg/l) influent Effluent Efficiency (%) TSS (mg/l) influent Effluent Efficiency (%) The mean BOD removal records at 69% with a maximum of 70 % and minimum of 65%. Even though, the difference in efficiency is marginal, the quantity of removal at the maximum concentration is more than the value at minimum one. The COD removal efficiency fluctuates in between 57 % and 61 % with the mean value of 59%. In the case of TSS, the mean efficiency removal falls at 64%. Soil matrix is efficient in TSS and the maximum removal efficiency of 74% supports the first part of this statement. The BOD concentration in the effluent is lesser than 30 mg/l, which is the level stipulated by Pollution Control Board for safe disposal. In order to increase the detention time, size of the may be increased to get more efficiency. Root zone bed (RZB) In the black water treatment, root zone bed follows the septic tank. Overflow from the septic tank is connected as influent to root zone bed (RZB). Periodically measured pollutant parameters at the inlet and outlet of RZB are presented in table 3. Mean BOD, COD and TSS influent concentrations, during the monitoring period, were 65 21

7 mg/l, 84 mg/l, and 44 mg/l respectively. These concentrations decreased along the planter bed, indicating that organic matter removal is achieved. Variation in organic concentration in the grey water generated is observed. Table 3.Removal characteristics of Root Zone Bed Pollutant characteristics variation along the Root Zone Bed Sl.No Parameters Mean Minimum Maximum 1 BOD (mg/l) influent Effluent Efficiency (%) COD (mg/l) influent Effluent Efficiency (%) TSS (mg/l) influent Effluent Efficiency (%) Normally, the BOD in the domestic sewage will be in the order of 200 mg/l to 300 mg/l. The influent BOD value shows removal taken place in the septic tank. The mean BOD removal records at 55% with a maximum of 56 % and minimum of 54%. Though, the difference in efficiency is marginal, the quantity of removal at the maximum concentration is more than the value at minimum one. The COD removal efficiency fluctuates in between 51 % and 58 % with the mean value of 54%.. In the case of TSS, the mean efficiency removal falls at 66%. Soil matrix is efficient in TSS and the maximum removal efficiency of 72% supports the first part of this statement. In most of the observations, the BOD concentration in the effluent is lesser than 30 mg/l, which is the level stipulated by Pollution Control Board for safe disposal. In a few cases, BOD value in the effluent is higher than 30 mg.l and very close to the threshold value. Mostly during winter, the higher value is noticed inferring reduction in efficiency in the septic tank. The locally available plant, Typha species is grown in the RZB. The size of bed provided is little lesser than the one recommended elsewhere. In order to increase the detention time, size of the may be increased to get more efficiency. Total coliform level has come down and RZB is found to efficient in FC removal. OPERATION AND MAINTENANCE Planter bed and RZB have been in continuous operation since July 2009 and is absolutely maintenance free. Do not need man power and other. Maintenance works done in the past two years are listed below. 22

8 Planter bed Cleaning of inlet chamber once in a month to remove solids settled in between porous media to maintain the flow sans blockage, Gravel media is removed, washed and dried. Repacking is then done, Harvesting matured plants and replanting. RZB Gravel media in the Inlet chamber is cleaned once in three months, Cutting down the matured typha plants once in six months. Cost and benefit The construction cost as on 2009 rates came as Rs.15000/=. Benefits derived from the system are many and listed below Open drain is not necessary in front of house, and hence odour and mosquito free, Health benefit, Saving in electrical energy cost, Rs.450/month. Daily half-an- hour pumping is to be done for raising plants and vegetables. When recycled, pump operation becomes unnecessary and hence saving. Water used is well within the house premises- pumping and recharging, Cost for purchasing vegetables becomes less. Tomoto, brinjal and pumpkin are grown and produce are used. CONCLUSION Ever increasing population poses stress on water supply and sanitation sector to maintain public health. Whatever quantity supplied as water supply, returns as wastewater. Cities are growing like anything and which demands more and more wastewater handling facilities. Huge cost is needed for community based wastewater treatment and disposal system rendering burden to the government. Individual household level wastewater treatment and disposal may release stress to governments. Two years of operation of pilot model for grey water treatment and black water suggests that the on-site Planter bed for grey water and RZB with septic tank operate successfully and remove pollutant satisfactorily It is totally maintenance free and economically viable for individual houses in rural as well semi-urban developing areas. Further research on this line is also solicited.. ACKNOWLEDGEMENT Authors are thankful to Managing Director, TWAD Board, Chennai for permitting to present the paper. REFERENCES 1. Ottoson,J, and Stenstrom,T.A, 2003, Faecal contamination of grey water and associated microbial risks, Water Research, 37(3), Friedler,E. 2004, Quality of individual domestic greywater streams and its implication on on-site treatment and reuse possibilities. Environmental Technology, 25(9), Jefferson, et al, 2004, Greywater characterization and its impact on the selection and operation of technologies for urban reuse. Water Science & Technology, 50(2), NRMMC Natural Resource Management Ministerial Council, Environment Protection and Heritage Council and Australian Health Minister s Conference, 2006, National guidelines for water recycling: Managing Health and Environmental risks, 23

9 Natural Resource Management Ministerial Council, Environment Protection and Heritage Ministerial Council, Australian Health Minister s Biotext Pty Ltd, Canberra. 5. ACTC (Australian Capital Territory, Canberra), 2008, Greywater use guidelines for residential properties in Canberra Second Edition, ActewAGL ACT Health; ACT Planning and Land Authority, Territory and Municipal Services. 6. WHO, 2006, Guidelines for the safe use of wastewater Excreta and Greywater, Vol. I-IV, Wastewater use in agriculture, Geneva, Switzerland. 7. GOI, Ministry of Rural Development, DDWS, 2008, Solid and Liquid Waste Management in Rural Areas- A Technical Note. 8. Rengasamy,V.R., and Subramanian, V, 2002, Treatment of wastewater from small and medium sized communities using root zone bed-a case study, Journal of IWWA, Vol.XXIV, No;2, PP Godfrey,S. et al, 2010, Safe greywater reuse to augment water supply and provide sanitation in Semi-Arid areas of rural India, Water Science & Technology, 62(6), Gikas,G.D and Tsihrintzis,V.A. 2010, On-site treatment of domestic wastewater using a Small-scale horizontal subsurface flow constructed wetland, Water Science & Technology, 62(3), Liu,C.H and Lo,V.K. 2001, Ammonia removal from composting leachate using Zeolite.I.Characterization of Zeoloite, Journal of Environ.Sci.Health Part A, 36,