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Increasing flood risks in Thailand are leading to new challenges for flood management and subsequently for livelihoods, which are still significantly agricultural. Policy makers prefer building flood protection infrastructure over utilizing non-structural measures like urban planning regulations to mitigate risks. We argue that unplanned urbanization intensifies flood risks and livelihood vulnerability and may even create new poverty patterns in peri-urban areas. However, urbanization can also strengthen the adaptive capacity of people in flood risk areas by providing more secure employment opportunities. We assess the livelihood vulnerability of Pra Lab, a peri-urban area of Khon Kaen City in Northeast Thailand, using a qualitative and quantitative analysis. The study relies on a vulnerability index developed from a household survey and rainfall statistics, complemented by household in-depth interviews. We further identified factors of unplanned urbanization in Khon Kaen City and Pra Lab through interviews with relevant local government offices. Our findings show that Pra Lab's household livelihoods are moderately vulnerable to flood due to high financial (i.e., income, debts) and physical vulnerability (i.e., housing, urban systems, infrastructure). Major factors of unplanned urbanization that contribute to flood risks are lack of land use regulations, inefficient monitoring of land and house elevations, reduced pervious surfaces, ineffective water governance and insufficient wastewater treatment.

A B S T R A C TThe purpose of the present study is to investigate the effects of nutrient starvation of microalgae on its nitrogen (N) and phosphorus (P) uptake, characteristics of extracellular polymeric substances (EPS), and algal sedimentation. An experiment was carried out by starving the wastewater-tolerant microalgae Chlorella sp. ADE4. The algal cultivation was put under various conditions of nutrient starvation in order to enhance nutrient removal and algal cell separation. The experimental results showed that 40 h of nutrient starvation prior to the cultivation did affect nutrient removal of Chlorella sp. ADE4. When using synthetic wastewater, the N-starved algae was the most effective in removing 82% of N in 48 h and 92% of P in 24 h. However, the starvation conditions did not cause noticeable removal improvement when microalgae were tested with real wastewater effluent. N and P removal efficiencies of 57 and 100%, respectively, were achieved in 48 h in real wastewater effluent. The lower N removal efficiency was caused by P limitation in the real sewage effluent. EPS were analyzed to evaluate if they play a role in algal cell agglomeration and subsequent microalgal separation. Carbohydrates and protein were indicated as major components in soluble and bound EPS. It was found that starvation of microalgae for 40 h could induce higher EPS production. Interestingly, the N-starved microalgae contained a large protein fraction in their EPS and low N content in their biomass. However, a significant correlation between EPS content and sedimentation efficiency was not observed in this study.

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