Green residues from Bangkok green space for renewable energy recovery, phosphorus recycling and greenhouse gases emission reduction.

Effective ways to integrate human life quality, environmental pollution mitigation and efficient waste management strategies are becoming a crisis challenge for sustainable urban development. The aims of this study are: (1) to evaluate and recommend an optimum Urban Green Space (UGS) area for the Bangkok Metropolitan Administration (BMA); and (2) to quantify potential renewable resources including electricity generation and potential nutrient recovery from generated ash. Green House Gases (GHGs) emissions from the management of Green Residues (GR) produced in a recommended UGS expansion are estimated and compared with those from the existing BMA waste management practice. Results obtained from this study indicate that an increase in UGS from its current 2.02% to 22.4% of the BMA urban area is recommended. This optimum value is primarily due to the area needed as living space for its population. At this scale, GR produced of about 334kt·y-1 may be used to generate electricity at the rate of 206GWh·y-1 by employing incineration technology. Additionally, instead of going to landfill, phosphorus (P) contained in the ash of 1077 t P·y-1 could be recovered to produce P fertilizer to be recycled for agricultural cultivation. Income earned from selling these products is found to offset all of the operational cost of the proposed GR management methodology itself plus 7% of the cost of BMA's Municipal Solid Waste (MSW) operations. About 70% of the current GHGs emission may be reduced based on incineration simulation.

Quantification of phosphorus flows throughout the consumption system of Bangkok Metropolis, Thailand.

Due to unequal distribution of the world's Phosphorus (P) sources for fertilizer production, an evaluation of P flows throughout the consumption system of a city is needed. The prime objective of this paper is to assess and prioritize P recovery options as to bring about, as much as possible, a close-looped P-for-food system. Using the Bangkok Metropolitan Administration (BMA) as a case study, the aim of this work is to quantify the potential mass flow of P for four major types of urban wastes: domestic wastewater (DWW), septage sludge (SS), food waste (FW) and green garbage (GB) and to determine the recoverable stock of P available. The consumption of food and supplements such as cleansing products and fertilizer is estimated at a rate of 1146.4 g P·cap(-1)·year(-1). P contained in wastes being discarded from its average 7.9 million population plus 33.8 million Bangkok-visiting tourists per annum is determined to be 8.01 kt P annually. Only 4% of the above quantity is recycled and used internally for cultivating plants grown in public parks. An annual amount of 7.68 kt P was found to be disposed of in landfills (6.23 kt P) and in the river systems (1.45 kt P). From the findings of this study, therefore, it is recommended that P recovery efforts from BMA's urban wastes should be focused on wastes enrouted to landfills since these constitute 81% of P discarded. As a consequence, solid waste combustion coupled with energy recovery from P-binding organics may be an appropriate means of P recovery. This technology has the potential to reduce waste volume, generate electricity, and produce P-containing ash that can be used for further application on farm lands.