Assessing nutrient flows by Material Flow Analysis (MFA) in Hoang Tay and Nhat Tan Communes, Hanam Province, Vietnam | |
| Author | Do Thu Nga |
| Call Number | AIT Thesis no.EV-09-06 |
| Subject(s) | Nutrient pollution of water--Vietnam--Hanam Sewage--Purification--Nutrient removal--Vietnam--Hanam |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | This MSc research was conducted to test the applicability of the adapted Material Flow Analysis (MFA) methodology developed by Montangero (2006) in a rural context of Vietnam. The method was applied to characterize and quantify nutrient flows (N and P) in the environmental sanitation and agriculture system (including livestock, fish pond and crop production) in low-income villages in Hanam Province, where data on environmental sanitation and agricultural practices is scarce and uncertain. Furthermore, this research was also conducted to identify critical control points related to water pollution caused by nutrients, and to assess the impact of improvement scenarios on the nutrient balance in the system. The study resulted in the development of a MFA model for the environmental sanitation and agriculture system in a rural setting of Vietnam, which allows identifying critical points in the system related to nutrient management, and enables the assessment of the impact of different scenarios on nutrient consumption, nutrient discharge into the environment and nutrient recovery for food production. Model parameters are described as probability distributions, enabling the quantification of uncertainty propagation in the stochastic MFA model, and reflecting accuracy of input and output values. Model parameter values were calculated based on a Monte Carlo simulation. The model was validated based on a series of independent plausibility criteria. The calibrated MFA model enabled to identify the critical points of the system in terms of nutrient management. The main nutrient sources to the system were chemical fertilizer supplied to agriculture (177±15 tonN/year and 25±6 tonP/year) and commercial fodder (175±13 tonN/year and 44±11 tonP/year). Main nutrient flows within the system related to (a) animal manure (153±10 ton N/ year and 69±8 tonP/ year) and (b) on-site sanitation systems: 90% of N and 78% of P delivered to the households in form of food and detergents was finally discharged with the excreta, wastewater (grey water from households and effluent from on-site sanitation) and solid waste.. Pollution and contamination of surface water, soil and groundwater caused by excessive use of chemical fertilizers, discharge of untreated wastewater from households and manure from the livestock system were identified as the main problems in the system. The scenario analysis demonstrated that if development trends are as expected until 2020, and no measures are taken to improve nutrient management, N and P in wastewater will increase by 48% and 51%, respectively. N and P in sludge and organic solid waste are expected to triple as compared to 2008. By improving faecal sludge management (i.e. increasing emptying frequency and improving treatment), by replacing pit latrines and pour-flush latrines by septic tanks, and by pre-treating greywater from households in septic tanks prior to discharge, nutrient discharge to surface water could be reduced by 63% of N and 59% of P (with a reduction of 56% of N, 53% of P in wastewater and 67% of N, 65% of P in sludge and organic solid waste). The adapted MFA methodology is a promising mathematical model to apply in developing countries where data scarcity and uncertainty is an issue. This method optimises amount of necessary parameters by parameter assessment through expert interviews and household questionnaire. Moreover, by comparing with plausibility range of parameters collected from previous studies and expert judgements as well, uncertain data can be assessed. Besides, parameters are all represented in probability distributions, enabling the assessment of the accuracy and uncertainty of MFA values. |
| Year | 2009 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Visvanathan, C. ;Shipin, Oleg V. ;Morel, Antoine; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2009 |