Date Published: September 13, 2017
Publisher: Springer Berlin Heidelberg
Author(s): Jin Zhang, Wei Wei, Shuang Lin, Jie Lu, Qing Hu.
In this paper, the removal of As and the transport and migration of As at the process of activated sludge system was studied. The results showed that the activated sludge system has high removal efficiency for As, and the removal efficiency could be nearly 100%. The initial concentration of As has effect on the removal efficiency, and within the experimental scope, the increase of initial concentration of As improved the removal efficiency for As. The distribution of As in the surface and internal in activated sludge indicates that in the process of activated sludge, the As was first transferred from water to the surface of solid and was adsorbed by the surface and then transport to the interior of microbes and take part in some metabolisms of the microorganisms. The adsorption of As by activated sludge conforms to Freundlich adsorption isotherm, and the removal of As in activated sludge system follows to the pseudo second order reaction kinetics.
With the development of industry and agriculture, there are more and more heavy metal pollution in environment. As one kind of heavy metal, arsenic (As) has caused serious influence on water environment. By estimated, the total amount of As flow into the water environment is about 110 thousand tons per year (Bansod et al. 2017; Zheng et al. 2017; Mukherjee et al. 2017).
Because of many surface functional groups and characteristics of adsorption of activated sludge, the activated sludge system has high performance for the removal of As. There are mainly the characteristic peaks in FT IR spectrum (Fig. 5) of the stretching vibration of –OH of alcohols, acids and acid-like substances on the surface of activated sludge (Lee et al. 2013). The stretching vibration peak in the range of 2930–2925 cm−1 (Liu et al. 2012; Zhao et al. 2015) is the –CH peak. In the range of about 1640–1660 cm−1 (Song et al. 2014), the stretching vibration peaks are the peaks of –C=O and –CN on the protein. At around 1250 cm−1 (Yan et al. 2010), the peak is the –C=O deformation peak of the nucleic acid. At 1024 cm−1, the peak is the stretching vibration peak of –OH in polysaccharide. The peaks at below 1000 cm−1 are the fingerprints of phosphate functional groups, sulfur functional groups, etc. (Aravindhan et al. 2004). Large number of surface functional groups contribute to the removal of As.Fig. 5The FT IR spectrum of activated sludge