Climate Change Potentials of Sanitation options: Nepal Prospective Nam Raj Khatri 1, 1.WHO Nepal ABSTRACT: In Sanitation is very essential need and part of life for human beings. Sanitation and hygiene behaviour has link to health and development. People are using various ways of disposing waste and excreta. Different options have different level of potentiality for CO 2 emissions causing climate change(metcalf). At present, government has policy to support people to construct toilet simple toilet with on site disposal system in the wide spread rural areas and water carries system in urban areas with various technology based on local decisions. This paper analyse the potential of CO 2 emissions from various options of sanitation considering decomposition process. According analysis made in this paper onsite sanitation system with pit decomposition is found to be highest and oxidation pond as lowest in terms of potential for CO 2 emission. In Nepal onsite sanitation with pit disposal system is most prevailing adding 62kg/person/year which is 3 % of average emissions. It is suggested that the government support to community to develop or improve their sanitation system based on additional criteria i.e. potentiality for carbon emissions of the sanitation system. This kind of criteria will give rise to change policy of government for the sake of better climate. People living in the village and those who would like to adopt sanitation system with minimum carbon emission should get maximum support and people who would like to have system with maximum carbon emission should get minimum support. This kind of criteria will rank sanitation system in terms of climate change potentiality.. INTRODUCTION: Nepal Nepal is situated on the southern transitional terrain of the central Himalayan in the Asian continent of the globe. It is located in South Asia between two large countries China and India. The country covers an area of 147,181 sq. km, and it is divided into three ecological regions based on altitude. These ecological regions -- mountains, Hills and Terai (flat land) -- cover 35%, 42% and 23% of the total area of the country respectively. These regions are quite diverse in terms of climate, topography and socio-economic characteristics. Present population of the country is 28 million. About 16 % of the total population resides in the urban areas. There are 75 districts and 4000 village development committees (VDC) Nepal is one of the poorest but environmentally rich countries in the world, with very few carbon emissions of its own. Carbon emissions of Nepal are only 1.9Ton/person whereas world's average is 3.9 Ton/person. Nevertheless, it is extraordinarily vulnerable to the effects of a changing climate: Temperature in the Himalayas is rising more rapidly than the global average temperature is doing. Average temperature in Nepal has risen 0.6 degrees over the last decade, compared with an increase in average temperatures globally of 0.7 degrees
over the last hundred years. Scientists worry that the impact of what is happening in Nepal will be felt all over Asia. Nepal has three things to do in the context of climate change. First to take advantage of being an environmentally rich i.e. low carbon emitter, second, to think about adaptation and third, to take more precautions so as to minimise further carbon emissions. This paper determines the extent of carbon emissions by various options of sanitation system in Nepal and explores ways to minimize it and sets broader criteria for supporting sanitation systems. Climate Change concepts overview Solar radiant energy flux from the sun, just outside the earth s atmosphere, is 1.353 KW/m 2. If the all of this energy is received and absorbed by the earth then the black body radiation from the outer surface of the earth will be the same energy received. According to Stefan s law temperature of the earth for this amount of radiation would be about 5 0 C. In fact earth reflects about 30 percent of all the incoming solar radiation back to outer space from the tops of cloud, icy surface and oceans. With this 70 percent solar energy equivalent earth s temperature for blackbody radiation would be -19 0 C. But earth s average temperature has been maintained to about 15 0 C. This means atmosphere is preventing the outward flow of radiant heat. To maintain the average temperature 15 0 C about 14 percent of radiant energy has to be retained. Basically energy radiation from sun falls in the visible range and that of the radiation from the earth falls in the infrared. Green house gases have ability to trap the infrared rays reflected by the earth. The greater the quantity of GHGs, the more the heating up of the atmosphere will take place. This phenomena is essential for life on earth to exist by keeping earth s average temperature around 15 0 C. But, more GHGs causes rise in temperature from present level is termed as global warming From a pre-industrial concentration of 280 ppm, the present level of greenhouse gases in the atmosphere has reached 430 ppm, and is increasing by approximately 2.5 ppm per year.total composition of GHGs in the atmosphere is like Carbon dioxide (55%), Methane (15%), Nitrous oxide (6%), CFC(17%) ant other(7%). In the atmosphere Methane is 20 times, Nitrous oxide 200 times, CFC 12000 times effective for green house effect than the Carbon dioxide. As the volume of the CO 2 is much higher than other GHGs, it is more of concern in the context of global warming.(air Polution Control Engineering) Current best estimate, based on projection of all future GHGs, is that mean temperature of earth will increase by 0.2 0 C per decade. This will lead 2 o C rise in earth average temperature by 2100, and lead to corresponding rise in the mean sea level by 6 cm/ decade. Climate change will impact some of the fundamental pillars of the life like food, water, air and shelter. The warming of the earth is gradual but the frequency and severity of extreme weather events such as intense storms, heat waves, droughts and floods could be abrupt and the consequences will be dramatically felt. Effect of Climate Change on Sanitation The global temperature rise will lead to an intensification of the hydrological cycle, resulting in drier dry seasons and wetter rainy seasons, and subsequently heightened risks of more extreme and frequent floods and drought. Changing climate will also have significant impacts on ways of sanitation. Impact of
Climate Change on water will also have impact on sanitation. New kinds of vectors will emerge which requires different ways of sanitation. Effect of Sanitation on Climate Change Sanitation is basis of life. Safe life is only possible in improved sanitation. But many people are deprived of this basic human need without which, human beings cannot live healthy life. It plays a vital role in nearly every function of the society Lack of sanitation causes serious illnesses such as diarrhoeal diseases, which kill over 2 million people every year (the vast majority children, mostly in developing countries. Sanitation system determines availability water for sanitation and same time it impacts safety of water. Poor health constrains development and poverty alleviation. (Climate Chance and Water Resources) Sanitation system and ways of disposal involves emissions of CO 2 and CH 4 Some process consumes energy which contributes to carbon emission and leads to climate change to some extent. This paper aims to calculate carbon emissions associated to various ways of sanitation and find how policy maker s planners, implementers and people can make some difference by changing habits. Sanitation situation and practices in Nepal In Nepal, 40 percent of people have access to some kind of sanitation. About 50% toilets are constructed as dry pit and half as flush toilets. 5 percent population residing in urban area have access to sewerage system of which very small portions are treated. Treatment technology include oxidation pond, anaerobic pond, oxidation ditch, vegetative wetland(reed bed) etc. Major portions are discharged to nearest river without treatment or after partial treatment. Types of sanitation and carbon emissions There are various types of toilets and excreta disposal system. Here we are concerned with decomposition of excreta and waste. In average 30g/persons BOD equivalent organics are released from sanitation (Toilets). Depending upon the system these organics gets transformed in to CO 2, CH 4, energy and other minerals. Aerobic process produces CO 2, where as anaerobic process produces CO 2 and CH 4. If the collected gases (CH 4 ) are burned it converts in to CO2. Mechanical aerobic system requires oxygen which is indirectly equivalent to CO 2. CH 4 is used as fuel for cooking will avoid CO 2 emission from existing wood fuel system. This fact has not been considered here. In this context sanitation can be categorized in to following types On site system with pit decomposition: These includes all kind of toilets in which excreta is disposed on site in the pit where decomposition take places aerobically with emission of CO 2 and CH4. On site system with connection to biogas Plant: These include toilet connected to gobar gas plant in which decomposition take place anaerobically with emission of CO 2 and CH 4 and CH4 is used for cooking. When CH 4 is burned it gets converted in to CO 2 as a result only emission of CO 2 takes place. Water carriage system with natural aerobic decomposition: This involves oxidation pond and dilution to river. Decomposition takes place aerobically using oxygen available in the surrounding air as a result emission of CO 2 takes place. Water carriage system with mechanical aeration system: This involves aerated lagoon,
activated sludge process(asp) of various kinds which involves use of oxygen through aerator and diffusers. Process involves use of energy which indirectly represents equivalent emission of CO 2 based on type of energy. Aerobic decomposition also involves emission of CO 2. Water carriage system with anaerobic decomposition with out gas collection: This involves anaerobic ponds and other digester in which no gas is collected. This is same like decomposition in the pits which produces CO 2 and CH 4. Water carriage system with anaerobic decomposition with gas collection: This involves anaerobic process like UASB, In-Hoff tank in which gas are collected and used as fuel. This is similar to biogas plant in which only emission to atmosphere is CO 2. Disposal In landfill sites: This includes disposal of sludge from septic tank and treatment system to landfill sites. Both CH 4 and CO 2 are produced. Ultimate emission depends on gas collection system. In many cases gases are burned. Analysis for gases emissions associated with sanitation system Ultimately all organics associated with human waste gets transformation through decomposition either in pit or in treatment plant or later in nature. How it decomposes matters for climate change potentiality. Either it produces CO 2 or Both CO 2 and CH 4 depending on decomposition process. Completely aerobic system in nature: stiochoimetry of Aerobic decomposition in general is C 5 H 7 NO 2 + 5O 2 5CO 2 + 2 H 2 O + NH 3 + Energy (113) (160) (220) This indicates 160 gm of O 2 which is BOD produces 220 gm CO 2. This implies that 1 Kg BOD produces 1.4 kg CO 2 Completely Aerobic system with artificial aeration: stiochoimetry of Aerobic decomposition in general is same. Only difference is oxygen is supplied through artificial aeration. Oxygen required for the process is given by O 2 required =1.47 x BOD 5 removed - 1.4 x biomass produced In a system if 90 BoD 5 is removed and of which 30 percent is converted in to bio mass then O 2 required will be about 1kg O 2 /kg BoD 5 removed. Biomass also undergoes decomposition. Assuming that biomass also undergoes aerobic decomposition total CO 2 produced is same as that produced in natural Aerobic system. In general 0.7 kwh energy is required to produce 1 kg O 2. And 1 khw energy is equivalent to o.6 kg CO 2. Therefore 1kg O 2 through artificial aeration becomes 0.42 kg CO 2 This indicates that 1 kg BoD produces 1.4 kg CO 2 and requires 0.42 kg O 2 Completely anaerobic process with out gas use: Anaerobic process are less efficient for producing biomass. Biomass production is negligible. Typically CO 2 and CH 4 are produced as given by following stiochoimetry. C 6 H 12 O 6 3CO 2 + 3 CH 4 (180) (132) (48) BOD equivalent of organic waste is given by 3CH 4 +6O 2 3CO 2 + 6H 2 O (48) (192) (132) This indicates that one kg BOD produces o.25 kg CH 4 and 0.68 CO 2
Completely anaerobic process with gas use: If CH 4 is burned it produces CO 2 3CH 4 +6O 2 3CO 2 + 6H 2 O (48) (192) (132) This indicates that I kg CH 4 produces 4 kg CO 2 His indicates that one Kg BOD produces 1.68 Kg CO 2 Considering 30gm/person BOD equivalent of organics from sanitation, summary of carbon emission by various processes are given in the table 1. Findings One person contributes about 30 gm/day BOD equivalent organic waste. One kg BOD produces 1.4 kg CO 2 in aerobic process and 1.68 CO 2 in anaerobic process with gas used One kg of BOD produces 0.68 Kg CO 2 and )0.25 kg CH 4 One kg BOD requires 1 kg O 2 in aerobic system with artificial aeration which is equivalent to 0.42 kg CO 2 in natural aeration system this is not required Assuming that per capita excretion of organic waste is 30 gm, yearly equivalent CO 2 emission is 62kg in onsite pit disposal system and anaerobic pond system; 43 kg in septic tank followed by aerobic system; 20kg in biogas system; 18kg in mechanical aeration system and 15kg in natural aeration system. Considering widely used onsite pit system as base line, relative carbon emission of other system is same in anaerobic pond, 69% in septic tank, 29% mechanical aeration system, 32% in anaerobic process, 29% in biogas system and 24`% in natural oxidation system Widely used onsite sanitation system with pit disposal makes emission of 62kg CO 2 /person/year which is about 3% of national average. Since mechanical aeration is more potential for CO 2 emission in comparison to anaerobic system and in addition it requires energy anaerobic digestion system with gas collection should be promoted. FINDINGS: In Nepal, Supply management is challenged by geographical, economic condition and highly scattered settlements. But still there is scope for long term supply management through proper policy and coordination. Demand management seems equality important to supply management for giving value to precious water resources and making best use for meeting demand to some extent. There is scope of minimizing need of fresh water from public supplied through use of RWH and reuse of wastewater Conclusions Based on the analysis made here in the paper, we can recommend the followings, to move towards preserving ecosystem by reducing CO 2 emission to the extent they can do. 1. Onsite sanitation with pit disposal system causes maximum CO 2 emission hence should be discourage whenever there is other visible options. 2. Oxidation system causes least CO 2 emission hence should be encouraged wherever the land is available. 3. Aeration system with mechanical aeration system causes extra CO 2 for oxygenation over hence should be discouraged. 4. Any anaerobic system with out collection of CH 4 should be discouraged 5. Anaerobic system with CH 4 collection should be preferred as it causes minimum emission and saves energy.
AKNOLEDGEMENT This paper was derived based on analysis of potentials carbon emission from various options of sanitation using theoretical base from books and Nepal data and my experience of working for 20 years in this sector. My sincere Thanks to all colleagues of Department of Water Supply and Sewerage who commented on my views. REFERRENCES: Rural Water Supply and Sanitation policy 2005, Ministry References Report: Climate Change and Water Resources, Water Aid: Courtenay Cabot Venton, Environmental Resources Management, London Report: Water and Climate Change, Intergovernmental Panel for Climate change(ipcc) technical Report IV published by UNEP and WMO in June 2008 Book: Air Pollution Control Engineering, McGraw Hill International Edition Book: Wastewater Enginering, Tata McGraw-Hill Pulishing Compani, Metcalf & Eddy, INC Book: Onsite Wastewater Treatment System Manual, EPA Paper: Climate resilience water supply system in Nepal, Nam Raj Khatri, presented in online conference CLIMA 2010.