Real-time wastewater monitoring with IoT sensor network
Continuous pH, conductivity, and chemical composition monitoring at Quat Dong, Thuong Tin industrial park. Early-warning alerts now fire before discharge thresholds are breached — replacing weekly manual sampling that left days of risk undetected.
- Near-miss events caught in 90 days
- 27
- Discharge points monitored
- 3
- Sensor reading interval
- 60s
- Continuous monitoring
- 24/7
The challenge
HONG HA TRAFE CO., LTD operates an industrial facility in Quat Dong, Thuong Tin industrial park that discharges treated wastewater into the public waterway network. Vietnamese environmental regulations require that discharge must remain within strict thresholds for pH, conductivity, dissolved oxygen, and chemical oxygen demand (COD). Before this project, compliance monitoring was entirely manual: an environmental health and safety (EHS) technician collected grab samples at each discharge point on a weekly schedule and sent them to a third-party laboratory. Results arrived 3–5 days later. Between sample events, there was no visibility whatsoever on discharge conditions. This left 7-day windows of unmonitored risk. A process upset — a chemical spill, a treatment system failure, a pH control malfunction — could go undetected for days. By the time the next sample was collected and analysed, a discharge event may already have occurred, resulting in regulatory fines, reputational damage, and potential production shutdowns. The facility had been quoted enterprise IoT monitoring platforms by international vendors at six-figure price points — far beyond what the budget could support. They needed a cost-effective, purpose-built system designed for their specific discharge points and chemistry profile.
What we built
L'inno began with a one-day site walkthrough to map the discharge network, identify the three primary discharge points, and assess existing infrastructure (power availability, network connectivity, PLC access). **Sensor selection and deployment.** We specified sensors from Honeywell and Greenspan calibrated for the chemical profile of the client's wastewater: pH electrodes, conductivity probes, dissolved oxygen sensors, and turbidity sensors at each of the three discharge points. Sensors connect to industrial-grade Raspberry Pi-based edge gateways housed in weatherproof enclosures. **Edge-to-cloud data pipeline.** Each gateway publishes readings every 60 seconds via MQTT to an AWS IoT Core broker. Data flows into an InfluxDB time-series database on a managed instance, with 12-month rolling retention at full resolution and downsampled archives for long-term trend analysis. **Alert logic.** We worked with the EHS team to define a tiered threshold system: a yellow alert at 80% of the regulatory limit (email to EHS team), an orange alert at 95% (email + SMS to EHS manager and plant manager), and a red alert at 100% (all channels + automated control signal to the treatment system where PLCs allow it). Alerts include a trend graph showing the preceding 2 hours of readings. **Dashboard.** A React/Next.js web dashboard gives the EHS team a real-time view of all discharge points, historical trend charts, and a compliance log exportable for regulatory submissions. The dashboard is accessible on mobile — EHS managers can check discharge status from the factory floor.
The result
The system went live after a six-week deployment, covering all three discharge points with continuous monitoring. In the first 90 days of operation, the alert system detected 27 threshold-approaching events that the previous weekly sampling schedule would have missed entirely. In each case, the EHS team was notified via SMS within 60 seconds of the reading, allowing them to investigate and correct the process before discharge limits were breached. The manual sampling process has not been eliminated — it's still required for regulatory compliance submissions — but its role has shifted from primary monitoring to verification. The EHS technician now validates sensor readings with periodic grab samples rather than relying on them as the sole source of truth. The facility's environmental compliance record has been clean since deployment. The EHS manager now starts each morning by opening the dashboard rather than waiting for weekly lab reports.
Technologies used
Honeywell and Greenspan sensors (pH, conductivity, dissolved oxygen, turbidity). Raspberry Pi 4 edge gateways in IP67 enclosures. MQTT → AWS IoT Core → InfluxDB (time-series). React + Next.js dashboard. SMS/email alerting via AWS SNS and Resend. Modbus integration to existing plant PLC where available.
“The real-time monitoring system has been a game-changer for our environmental compliance. We used to wait days to find out if we had a problem — now we get instant alerts and can take action before any discharge limits are breached. It's given us peace of mind and has already prevented several potential incidents.”
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