Spatial and Temporal Variations of Dissolved Oxygen in Cha-Am Municipality Wastewater Treatment Ponds Using GIS Kriging Interpolation

Abstract

This study investigated the spatial and temporal variations in dissolved oxygen (DO) in the Cha-Am wastewater treatment ponds to assess treatment dynamics and to identify possible areas where the treatment train could be improved. Cha-Am is a small resort town with extensive beaches, located on the west coast of the Gulf of Thailand. The wastewater treatment system for Cha-Am consists of four ponds in sequence: aeration pond, sedimentation pond, extended aeration pond, and evaporation pond. Two YSI 6920 datasondes were installed near the inlet of the aeration pond and in the sedimentation pond, to measure dissolved oxygen (DO), pH, conductivity, temperature, and turbidity at 30 min time intervals over a 3 month period. DO averaged 3.09 mg/L and 3.33 mg/L, respectively in the aeration pond and in the sedimentation pond. DO generally varied over a diel cycle with higher values observed in midafternoon and lower values observed after midnight. DO often increased after a rainfall event. Ordinary Kriging (OK) interpolation in ArcGIS10.1 was used to map the spatial distribution of DO at different depths based on YSI spot measurements. OK indicated the highest DO concentrations were near the surface (0.5 m to 1.0 m); averaging 18.53 mg/L, 20.5 mg/L, 17.31 mg/L and 9.7 mg/L in the four ponds, but sometimes the concentrations were <2 mg/L near the bottom of the ponds. Two of the ponds are used as a wild catch fishery and low DO seems to negatively impact the fish. The spatial trend of DO shows that normally DO is lower at the inlet of the aeration pond than at its outlet even though mechanical aerators are operated through part of the day. Improved aeration and sunlight penetration through enhanced particle settling may be of benefit.

Spatial Patterns of Heavy Metals in the Sediments of a Municipal Wastewater Treatment Pond System and Receiving Waterbody, Cha am, Thailand

“…Ordinary kriging (OK) was used to assess spatial patterns of metals in each pond. Unlike the kriging results reported by Koko et al (2017) for the ponds where there were regular spatial patterns for dissolved oxygen, it is more difficult to generalize about the spatial patterns for metals in the sediment. The spatial patterns of Cu and Pb concentrations in the sediments from the aeration pond are shown in Figures 13 and 14.…”

“…Studies have indicated that kriging generally provides better results than spline and natural neighbour analysis (Voltz and Webster 1990;Laslett 1994;Pavão et al 2012;Duong and Gourbesville 2014). Different kriging approaches have been developed (Li and Heap 2014;Forsythe et al 2013; but ordinary kriging (OK) has been widely applied (Isaaks et al 1989;Robertson 2008;Soffianian et al 2015;Koko et al 2017) and was used here for the ponds and river. The general equation for estimating a value at a point z (Chang 2012) is:…”

“…Past studies (e.g. But et al 2016;Bhowmick et al 2017;Koko et al 2017) have examined the water quality and the efficiency of the pond system in managing conventional wastewater parameters such as chemical oxygen demand (COD), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), E. coli and dissolved oxygen, but to date no evaluations have assessed levels of metals in the ponds. The objectives of this study were therefore: to examine the spatial variation of metals levels, longitudinally, from the ponds on through the receiving river channel system, to the ocean; to compare metal levels in the ponds to those in the upper reach of the receiving river to assess the pond system as a source area; and to compare metal levels in the ponds and river with sediment quality guidelines to provide a first indication of environmental risk.…”

Relationships between key functional traits of the waterlily Nuphar lutea and wetland nutrient content

“…In such a situation, the oxygen concentration frequently decreases with depth and may even become null close to the substrate, even in low-depth ecosystems (Hutchinson, 1975). Therefore, dissolved oxygen is usually negatively correlated with ammonium and temperature at the bottom of such warm and ammonium-rich wetlands (Koko et al, 2017).…”

Augmented Terrain-Based Navigation to Enable Persistent Autonomy for Underwater Vehicles in GPS-Denied Environments

“…To read more about this technique, see [Tun83] and [Wat85]. [KIJT17]. Moreover, technique has been successfully used to create regional distribution maps for the interpolation of nonpoint sources of physical parameters, e.g., a high-precision underwater digital elevation model was developed in [ZXX15], concluding that kriging for terrain-aided navigation is better than other traditional interpolation methods in terms of accuracy.…”