Proceedings of the 12th International Conference on Environmental Science and Technology Rhodes, Greece, 8 – 10 September 2011

 

DHS (DOWN FLOW HANGING SPONGE) BIO–TOWER A SUSTAINABLE METHOD FOR WASTE WATER TREATMENT FOR DEVELOPING COUNTRIES Rakesh Kumar Bhardwaj*, 1 and Hariom Sharma2 1 2

Department of Chemistry, Dyal Singh College, Karnal – 132001, INDIA PWD Water Supply, Water Testing Laboratory, Karnal – 132001, INDIA e-mail: [email protected]

EXTENDED ABSTRACT Water is an environmental, social and economic asset and as such needs to be managed with the objective of conserving a common patrimony in the interests of the community at large. In spite of unprecedented advancement in technology, globalization and urbanization across the world, a vast number o f developing countries are lagging behind in providing basic sanitation and adequate water supply to their people. The treatment of waste water generated as sewage has become both an ecological as well as an economic necessity. The investigations over the years have observed that the presence of toxic compound in water has manifested itself in various types of diseases in human-being and adversely affect the plants growth. Discharge of chemicals from various industries causes hazardous effects on humans, animals and environmental balances. Substantial efforts are being made to document, understand, and explain the science behind these issues all over the world. A sustainable and cost effective technology approach has produced powerful arguments for reconsidering strategies of economic growth and development in favor of what can be consider as sustainable development. Study i s concerned wi th the m e a s u r e m e n t a n d analysis of sewage effluents of K a r n a l an d Pani p at city being drained into Yamuna River, an important tributary of Ganga (our pious GANGA) in the region of eastern Haryana (INDIA). The sewage samples have been analyzed for TSS, BOD, COD, ORP and pH . T h e concentration of toxic metals [ leads (Pb), chromium (Cr), cadmium (Cd) , and arsenic (As)] in the collected samples from Panipat have also been determined. The UASB (Upward Flow Anaerobic Sludge Blanket) is one of the natural, economically attractive method for treatment of domestic/industrial wastewater, well suited for tropical and subtropical countries. Anammox process offers the possibility of replacing nitrification and denitrification processes for removing ammonia nitrogen from wastewater with partial nitrification . The results of investigations show tremendous decrease in BOD and COD (up to 85 - 90%) o n t r e a t m e n t w i t h DHS(Down-flow Hanging Sponge)Bio-Tower, a combination of anaerobic (UASB) with aerobic (DHS) and advocating it as self-sustainable sewage treatment for developing countries. KEYWORDS: Waste water, Toxic chemicals, Sustainable methods.

Introduction: The increasing scarcity of water in the world along with rapid population increase in urban areas gives reason for concern and the need for appropriate water management practices. In the closing decades of the 20th century environmental pollution emerged as a major concern for the survival and welfare of mankind throughout the world. Modern civilization, armed with rapidly advancing technology and fast growing economic system is under increasing threat from its own activities causing water

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pollution, Singh et al.[1]. India is the seventh largest country in the world with a total landmass of 3.29 million sq. km, population over 1 billion, 31% of which live in urban areas spread over 5162 towns. With enormous natural resources and growing economy India is the second largest pool of technical and scientific personnel in the world. Pollution from small size industries (SSIs) puts the Indian regulators in front of a difficult arbitrage between economic development and environmental sustainability. Urbanization is forcing policy makers to examine the availability of Food & water and Energy resources . The uncontrolled growth in urban areas has made planning and expansion of water and sewage systems very difficult and expensive, Looker [2]. The pollution load is characterized by high colour content, suspended solids, nutrients and toxic substances such as heavy metals and chlorinated organic compounds. Central Pollution Control Board (CPCB) data suggests that domestic, agricultural and industrial pollution and the lowest value of Dissolved Oxygen (DO) at 0.1mg/lt make Yamuna the most-polluted river in the country. Yamuna River, an important tributary of Ganga (our pious GANGA) in the region of eastern Haryana (INDIA has the highest BOD amongst all rivers in the country at 36mg/lt. It has the highest count in the country of total coliform numbers and faecal coliform numbers at 2.6 billion MPN/100 ml and 1.7 million MPN/100 ml, respectively. The discharge of coloured wastewater from textile, leather, printing and other industrial effluents containing toxic compounds viz. Cd(II), Pb(II) and Cr(VI) is currently a major environmental concern in the developing countries because of their poor biodegradability, carcinogenicity and toxicity, Yadav et al. [3]. Azo-dyes are the most widely used among synthetic dyes, representing almost 70% of the textile dyestuffs produced, Knackmuss [4] . Storm water runoff and discharge of sewage into the water bodies are two common ways by which various nutrients enter the aquatic eco-system, Sudhira et al. [5] ; Kansal et al.[6]. The intersection of climate change, natural resource loss, population growth, and global economic recession has accentuated the crisis. Water use is the largest factor in energy use and conservation. Furthermore, human exposure to toxic chemicals, pharmaceuticals and trace organic contaminants, antibiotic resistant microorganisms, and natural toxins such as those created through harmful algal blooms is increasing through increased reliance on both groundwater and surface freshwater.. Aquatic Toxicity and Bioaccumulation: Triclosan, (5-chloro-2 (2,4-dichlorophenoxy) phenol), is a chlorinated diphenyl ether. It has been used for more than 30 years as a general antibacterial agent and is used in commercial products as diverse, toothpaste, cosmetics, antiseptic soaps, washing-up liquid, plastic kitchenware, toys, socks and underwear Adolfsson-Erici et al. [7] . It has been shown that dioxins, a group of persistent chemicals renowned for their toxic impacts on health and the environment, may be formed on incineration of triclosan and under the influence of sunlight Kanetoshi et al.[8] . A recent study showed that triclosan is resistant to degradation during sewage treatment and is available for absorption by aquatic organisms in the environment (Adolfsson-Erici et al. [7]. Following this research, concerns on the aquatic toxicity of triclosan led soap and detergent manufacturers in Europe to agree a ban on any increase in its use after 1998. Our current understanding of triclosan’s environmental effects is limited, there is evidence that triclosan is toxic to aquatic organisms and may influence both the structure and the function of algal communities in stream Adolfsson-Erici et .al. [7] . Aging water and wastewater treatment system infrastructure needs major enhancement and adaptive technologies to maintain and improve adequate public health protection Methods and Materials: The same sampling protocol was employed for each measurement. As the physical and chemical characteristics of sewage vary from top to bottom of the sewage depth as well as with time from morning to evening so the grab samples were collected at regular interval and were mixed together from the selected

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area of Karnal and Panipat(an industrial town) in a routine manner for 30 weeks in continuation covering seasons of year 2009-2010. Simultaneously the samples were also collected from the Down-flow hanging sponge (DHS) reactor Bio-Tower, installed at sewage treatment plant Karnal. The pH was measured using the Systonic pH meter-324. The samples were analysed for the BOD and COD as per the manufactures manuals for calibrations of the apparatus and operations. For the measurements of BOD, the BOD bottles of capacity 300 ml and the incubator was provided with a temperature control of  0.50 C. The estimation of suspended solids was carried out by measuring the weight of residue retained on the glass fiber filter (Whatman Grade 934 AH) in the known volume of the samples. For toxic metals analysis, samples were collected from Panipat in 100 ml polyethylene bottles and acidified with 0.5 ml of Conc. HNO3 to pH 2 and few drops of HgCl2 were also added to stop the microbiological activity. The pre-treated samples were taken into the polarographic cell with appropriate supporting electrolyte. Currents were measured at peak potential of concentrated ion after making blank corrections. All the mass measurements were performed on an electronic balance (Citizen). The experiments were carried out at 25  10C. The samples were stored in refrigerator before analysing and the reagents used in the estimation were of AR grade. Result and Discussion: Sewage is the wastewater released by residence and industries in a community. It consists of more than 99 % water with only less than 1 % of dissolved and suspended solid material. The volume of waste water generated from the different cities and being drained to the Yamuna river has been reported in Table No 1 The experimental results of our measurements in the samples of sewage for the BOD, COD, ORP TSS, VSS, pH, nitrogen and ammonia are reported in Table 2 and are graphically represented in Figure 1-5. Quantitation in all observations was made by standard addition method, Willard et al.[9] . Table 1 represents the average data of water parameters measured over thirty weeks for the release of untreated domestic and industrial inorganic and organic toxicants. Table No 1 : The volume of water being drained to Yamuna River City along Yamuna River Waste water sewage Treatment Unit MLD

Treated waste MLD

Yamuna nagger

> 76

One

40

Karnal

> 70

TWO

48

Panipat

> 82

Two

50

Sonepat

> 76

One

40

Delhi

> 4000

Three

2390

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Table 2 : The measured average values of pH , BOD, COD, ORP, TSS, VSS and Nitrogen. Time /Wee k

30

pH

ORP (v)

BOD (mg/kg)

Sewa ge

Sewa ge

Sewa ge

UAS B

7.19

242.5

176

55.9 3

COD (mg/kg)

TSS (ppm)

UAS B+ DHS

Sewa ge

UAS B

UAS B+ DHS

5.43

476.0

180. 7

27.7 6

VSS (ppm)

Sewag Sewag e e

230.3

156.3

Nitroge n mg/kg Sewag e

30.18

The Figure 1- 5 shows that the variation of studied parameters over the study period is not regular but at random. The studied parameter as a whole increases with alarming rate. The BOD5 measures the amount of oxygen microorganisms required in five days to break down sewage. The amount of BOD varies from 144 mg/kg to 228mg/kg averaged 176.0(mg/kg); while COD 335 mg/kg to 611 mg/kg averaged 476(mg/kg) and pH 7.05 to 7.33 averaged as 7.20. The cloudiness of sewage is caused by suspended particles. The TSS ranges from 155 to 348 ppm while the VSS is averaged as 150 ppm. The ORP (oxidation reduction potential) is a measure of energy potential. Table 1 indicates the values of ORP various from -152 V to -281 V averaged as -242.5 V An ORP in the negative range indicates reaction taking place is anaerobic, while the positive value of ORP indicates that the reaction is aerobic or there is presence of oxygen.

Figure 1 Variation of BOD, COD, TSS, VSS and ORP in waste water with Time (week)

Figure 2 Variation of BOD with Time (weeks) : Time (in weeks)

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Figure 3 -Variation of COD with

Time course of total Nitrogen Sewage

UASB eff.

DHS eff.

FPU eff.

60

mgN.L‐1

50 40 30 20 10 0

50

100

150

200

250

Time (Days)

Time course of Ammonium Sewage

UASB eff.

DHS eff.

FPU eff.

40

mgNH4‐N.L‐1

32 24 16 8 0 0

50

100

150

200

250

Time (Days)

Figure 4, 5 Variation of Total Nitrogen & Ammonia with Time (in days)

Many industrial plants discharged heavy metals and volatile organic chemicals (VOCs) directly into streams or inject them into the subsurface. The chemicals used in the dyeing factories viz sodium nitrate, aluminum sulphate, caustic soda and soda ash may be responsible for high value of the studied parameters. Similar results were also reported by Somashekar et al.[10] . The measured concentration of toxic metals Cr, Pb, As, and Hg in the sewage samples of Panipat town along with standard deviation have been summarized in Table 2. It can be seen from the tabulated values that the level of toxic metals in the waste water is much higher. The possible source of arsenic may be the coal based 1100 MW Power Plant and National Fertilizer Limited (NFL) Plant at Panipat. The wide use of CFL, Tube lights and pesticides may be responsible for the high value of Hg in the region. Table -3 Concentrations of toxic metal and standard deviation  in wastewater Metal ion

Supporting Electrolyte

Lead Chromium Mercury Arsenic

0.1M KCl 1 M NaOH 0.5M HCl + 0.5M H2SO4 Oxalate Buffer (pH 4.0)

Peak Potential(v) -0.44 -0.80 +0.19 -1.15

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Max. 139 112 28 17

Concentration (mg/kg)

 ±

Min. 52 69 11 6

1.6 2.6 2.4 1.2

Avg. 96 75 16 13

The main components of domestic wastewater are proteins, carbohydrates, detergents, tannins, lignin, fulvic acid, and many other dissolved organic compounds, Rebhun et al. [11]. Coliform bacteria are used as an indicator of disease-causing organisms, Kansal et al. [6]. Recently interest has turned to using non-living biomasses which have the advantage of increased tolerance of environmental conditions and no nutrient requirements. Aderhold et al. [12] and Williams et.al [13] have investigated the ability of milled fragments of three brown seaweeds, a commercially extruded alginate fiber and its waste product to remove heavy metals. A number of conventional treatment technologies have been considered for treatment of wastewater contaminated with organic substances. Commercial activated carbon is regarded as the most effective material for controlling the organic load. However due to its high cost and about 10-15% loss during regeneration, unconventional adsorbents like fly ash, peat, lignite, wood, saw dust etc. have been used for the removal of refractory materials, Pandey et al. [14] for varying degree of success. Ionic liquids holds promise to provide better alternative to the toxic solvents, Sheldon et al. [15] . Adsorption is one of the easiest, safest and most cost-effective methods for removal of organic material because it is widely used in effluent treatment processes (Balkose et.al [16], Nelson et al. [17]; Eye et al. [18] ; Johnson et al.[19] ; Deb et al.[20] ; Gupta et al.[21] ; Mott et al. [22] ; Viraraghavan et al.[23] . They have explored the use of fly ash as an adsorbent for treatment of wastewater to remove toxic compounds and colour. Pandey et al.[14] , has proposed a method for removal of copper from wastewater by taking fly ash as an adsorbent. The use of active filtration through alkaline media for the removal of phosphorus from domestic wastewater has been proposed by Johansson et al.[24]; and Drizo et al. [25] . Ozone is a very good oxidizing agent due to its high instability (reduction potential 2.07 V) when compared to chlorine (1.36 V) and H O (1.78V). It has potential to 2

2

degrade large number of pollutants like phenols, pesticides and aromatic hydrocarbons and is used since the early 1970s in wastewater treatment Robinson et al.[26] , Özbelge et al. [27] , Pera-Titus et al.[28] ). The major drawback of the use of this method is, ozone has short half-life, it decomposes in 20 minutes so require continuous ozonation and making this method expensive to apply, Slokar et al. [29] . Appropriate Treatment Technology: Based on experience from past mistakes in sewage treatment technology the developers should base the selection of technology upon specific site conditions and financial resources of individual communities. Anaerobic wastewater treatment is a biological wastewater treatment without the use of air or elemental oxygen. Applications are directed towards the removal of organic pollutants in wastewater, slurries and sludge. Complete replacement of aerobic with anaerobic technology is not yet possible as the effluent quality of anaerobic treatment systems is not up to par. The anaerobic treatment is considered as a pre-treatment technique and has been applied in Colombia, Brazil, and India, replacing the more costlyactivated sludge processes. There are different types of digesters available, some have been proven effective over time, and others are still being tested. One of the most suitable digesters for tropical conditions is the UASB. UASB plant at Karnal Harada et al. [30 – 33] has proposed a self-sustainable sewage treatment system with the combination of UASB as pretreatment unit and an aerobic reactor Down-flow Hanging Sponge (DHS) reactor as a post treatment unit shown in Figure 6. The proposed anaerobic-aerobic biocoenoses of UASB and DHS fulfills the need for a simplified treatment system for developing countries because of its low cost, and operational simplicity, along with sustainability of the system as a whole. The results in Table 1 and Figure 2 & 3 show a tremendous decrease of 97 % in BOD5 (176mg/kg to 5 mg/kg ) and

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94% in COD (476 mg/kg to 27mg/kg in the samples collected from DHS Bio Tower reactor at Karnal. BioGas

Anaerobic HRT : 6 Hr

Domestic waste

UASB - Effluent

Aerobic HRT : 2 Hr

Gas -Solid Separator

Anaerobic

Aerobic

HRT = 6 Hr

HRT 2 Hr.

Polyurethane Perforated Plate

BOD = 85 - 95 % COD = 85 - 92%

Aeration

Sponge Carrier Water Jacket

Sewage Tank

UASB- Pre Treatment Unit

BOD and COD effectively get oxidized in the downstream by the function of Polyurethane foam that can retain water and microorganism.

Final Effluent

Sludge Bed

DHS – Post treatment Unit

Figure 6 Schematic diagram of anaerobic (UASB) with aerobic (DHS) sewage treatment. Conclusions: India’s economic growth has resulted in increased urbanization and quality of life for millions in their urban centers. This rapid economic expansion has led to increased demands on water resources for power generation, industrial uses, and agriculture. In a country with existing water shortages, this creates a tremendous water resource management challenge. The industrial and agricultural sectors are the greatest consumers of water, and typically result in contaminated wastewaters.This paper discussed option to achieve sustainability in wastewater treatment. USAB (anaerobic digester) in combination of DHS ( aerobic ) hybrid reactor encourage “zero-discharge” technology. The urban areas of many developing countries are growing rapidly, ecological sanitation systems must be implemented that are sustainable and have the ability to adapt and grow with the community’s sanitation needs. To achieve ecological wastewater treatment, a closed-loop treatment system is the need of hour. The traditional linear treatment systems need be transformed into the cyclical treatment to promote the conservation of water and nutrient resources. It can be concluded from this study that combination of anaerobic (UASB) with aerobic (DHS) a self-sustainable sewage treatment is a good alternative to other conventional treatment system. Acknowledgement: Author thank Dr. H Harada, Professor Tohoku University Japan for providing permission to collect the samples from 1 MLD Bio-Tower (DHS reactor) Karnal. References 1. Singh B., Brar S.P.S. and Bishnoi S. R. (1998) Quality of drain water of Punjab, Indian J Environ. Health. 31, (3), 262-266. 2. Looker, N. (1998) Municipal Wastewater Management in Latin America and the Caribbean, R.J. Burnside International Limited, Published for Roundtable on Municipal Water for the Canadian Environment Industry Association. 3. Yadav A. K., Singh B. K. and Pathak S. K. (1998). Effect of mixed effluent on properties of ground water and irrigated soils. J. Ind. Soc.Soil Sci. 46, 427– 429 4. Knackmuss H J. (1996). Basic knowledge and perspectives of bio-elimination of xenobiotic compounds. Journal of Biotechnology 51, 287-295. 5. Sudhira H. S. and Kumar V. S. (2000). Monitoring of lake water quality in Mysore City : Proceeding of lake 2000, Bangalore, India, Indian Institute of Sciences. 1-10. 6. Kansal, A; Rajeshwari, K. V.; Balakrishnan, M., Lata, K. and Kishore, V.V.N. (2003). Anaerobic digestion technologies for emery recovery from industrial wastewater–a study in Indian context. TERI Information Monitor on Environmental Science.3,67-75. 7. Adolfsson-Erici, M.; Pettersson, M.; Parkkonen, J.; Sturve, J. Triclosan,( 2000) a commonly used bactericide found in human milk and the aquatic environment . Organohalogen Compd., 45, 83-86. 8. Kanetoshi, A., Ogawa, H., Katsura, E., Kaneshima, H., Miura, T., (1988) Formation of polychlorinated dibenzo-p-dioxinupon combustion of commercial textile products

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