Overview
An effluent outfall in South China discharges to a receiving water body under a discharge permit. Compliance samples were taken by hand at set hours, and the result arrived at the office days later. Between samples the plant had no picture of the stream it was sending out.
The operator wanted a continuous record instead of isolated grab results. The stream had to be watched for sharp changes in dissolved salts and temperature, and the outfall level had to be seen when flow backed up. All of it needed to reach one place without a new control room.
Challenges
Compliance by grab sample
Samples were taken by hand at set hours and the result reached the office days later, so the plant had no picture of the stream between samples.
A single point is not a trend
An isolated result cannot show a sharp change in dissolved salts or temperature while it is developing.
Backed-up flow seen late
Outfall and wet-well levels were checked on site, so a restriction was found after the flow had already backed up.
Solution
Each instrument reports over the WES-WIO wireless terminal protocol to the edge gateway. The gateway merges the wireless nodes with the wired ones already in the plant and holds the values if the uplink drops. From there the data reaches the WES device management platform.
On the platform, conductivity and temperature are plotted against the permit band and the outfall level is shown beside them. Any value that crosses its threshold, or moves abnormally, sends an SMS and an email to the operator on shift, so a problem is seen while it is still happening.
