Abstract
A multilateral effort into managing nonpoint source pollution from agriculture has gotten much attention for many years. Particularly during the heavy rain season, run-off of turbid water from sloped farmlands, fallow ground and/or unmanaged uplands is deteriorated. Flocculant polymer, commonly used in wastewater treatment facilities, but now exploited to improve control of sediment turbidity by promoting flocculation of particles in construction site. This study used the flocculant polymer to control the discharge of agricultural nonpoint source pollution and focused on the understanding of how soil-water and polymer properties affect flocculation performance. Therefore, a series of flocculation experiments under different conditions was evaluated for better polymer clarification efficiency. Various factors such as flocculant dose, end-over-end inversion of a cylinder, and soil-water properties (pH, NaCl, organic matter) were studied. The effective flocculant dose that fulfilled fast settling rate was 10mg·L-1. Additional findings included that 1) increasing pH decreased the settling rate of soil particle; 2) a positive relationship between the percentage of turbidity reduction and a level of salinity in Kaolin suspension was observed, and 3) organic matter in soil solution inhibited PAM adsorption onto soil particles, which caused the reduction of flocculation performance. The findings of this study revealed that flocculant polymer possess good results as a turbidity reducetion measure and couldfurther provide valuable information to make better decision on establishment of Best Management Practice for handling agricultural nonpoint source pollution.
Highlights
The extent of the impact of climate change on humanity and the environment is not completely studied, but, massive efforts have been made
Flocculation behavior of soil aggregates followed by PAM adsorption onto soil particles requires a certain time to react and the best settling rate of soil particles was achieved at the pre-soaking time of 6 hr (Figure 2)
The flocculation kinetics of anionic polyacrylamide in Kaolin suspensions has been investigated as a function of pH (4 ~ 9), soil-water NaCl (0.5~10 mg·L−1) and soil organic matter (0.05 ~ 0.25 g·L−1)
Summary
The extent of the impact of climate change on humanity and the environment is not completely studied, but, massive efforts have been made. There are many potential areas affected by global climate change, for examples, human health, biodiversity, food production, economic growth, and water resources. The changing magnitudes of nonpoint source (NPS) pollution and the effectiveness of best management practices (BMPs) become magnified and uncertain. According to the report by Ministry of Environment (2006), the contributing rate of nonpoint source pollution to total loading for the four major rivers ranges from 42 to 69% depending upon the river basin characteristics [2]. It is well known that agricultural areas are the most problematic and even a small number of storms are usually responsible for the annual load and besides the meteorological factors are highly variable [3]
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