Illegal Wastewater Discharges and the Importance of Organics Monitoring in Municipal Sewer Networks

In the capital cities, pump stations are popular. For example, Dubai City has more than 200 pump stations, and Abu Dhabi has more than 250. Municipal wastewater treatment plants in the area are designed to handle COD levels of 1,000 PPM to 1,500 PPM. Anything higher than the permeable COD limit will cause stress to the plant operations, resulting in severe oxygen depletion, biological system overload and increased operational cost.

For this reason, many industries in the Middle East operate using a separate industrial sewer network, fed by separate pump stations designed to handle this high COD wastewater (up to 10,000 PPM). Yet not all industries are connected to this industrial sewer network, which has led to instances of illegal discharge to municipal plants.

Challenges for Municipal Wastewater Treatment Plants

When wastewater from food service, industrial manufacturing and other corporate industries enters the municipal wastewater network via illegal discharges, treatment processes are negatively affected. These operations happen overnight, when industrial wastewater tankers dump this high COD/BOD wastewater into sewer maintenance holes to avoid service fees associated with transmission and treatment for these industries.

There is no real-time water quality measurement system across these sewer networks, which means that these discharges are unknown until the wastewaters enter the municipal treatment plant. Currently, manual samples are collected on a daily basis at pumping stations, and then COD/BOD sampling is measured at labs. Some of the labs have the ability to measure salinity or conductivity in real-time, but even that does not provide a complete picture of the problem or help them to understand 20% of the water’s characteristics.

The unpredictable nature of these illegal discharges makes remediation and treatment hard to manage, but with faster detection, early response is possible. One way utilities are addressing this challenge is through organics monitoring, the continuous measurement of organic pollutants using parameters such as chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total organic carbon (TOC). By providing earlier visibility into changing wastewater conditions, organics monitoring helps operators identify pollution events before they affect treatment processes.

Benefits of Real-Time Organics Measurement

Badger Meter is a pioneer in real-time organics measurement, or spectrometry, with proven global references spanning 25 years. The spectro::lyser V3 probe features a very robust design and measures more than 10 parameters, including COD, BOD, TOC, TSS, nitrate, nitrite, HS-, color and contamination. Connecting to an advanced terminal, the con::cube V3 delivers real-time data instantly to the authorities wherever they are located, either to a central control room or via mobile or email alert.

By continuously monitoring wastewater quality at lift stations and other critical points throughout the sewer network, utilities gain an early warning of changing wastewater conditions. Unusual changes in pollutant concentrations can indicate illegal discharges or other process upsets before they reach the treatment plant, allowing operators to investigate, respond faster and protect downstream biological treatment processes while minimizing operational impacts.

Monitoring BOD and COD offers the following benefits for WWTPs:

Middle East Success Story

One of the largest municipalities in the Middle East operates more than 200 lift stations across a 300 km sewer network. Utility staff collect manual samples 2-3 times a day for compliance with regulations, and few sites are equipped with salinity sensors. High salinity disrupts microbial processes in treatment plants and kills freshwater organisms, while monitoring enables optimal treatment and safe discharge. With no visibility into real-time organics measurement, there were missing data points in the network.

Raw municipal wastewater showed the presence of heavy solids and fats, oils and grease from restaurant operations; while illegal dumping of used engine oils and high velocity water flow were challenges that plagued the utility for years.

To move toward proactive management of the wastewater network, the utility chose to deploy spectro::lyser probes in 30 lift stations to monitor COD and TSS values in real time. A bespoke, cylindrical steel cage with small holes was fabricated by operators to prevent larger particles from interfering with the sensors. The sensors were then mounted on the structure and fixed inside the cage before the unit was directly submerged into the water with a supporting chain.

The bespoke stainless steel cage and spectro::lyser assembly prepared for installation in a wastewater lift station.

In 75% of the monitoring locations, this customer has seen less maintenance compared to previous monitoring methods. Real-time water quality values are delivered to a central dashboard with the help of a con::cube V3 terminal. All the data is transferred to the customer’s cloud-based platform, where alerts are configured specifically to match needs for either low or high value reads.

With multiple options for displaying clear data, the customer can change the graphical displays from the start of installation to fit their needs. Furthermore, the full history of the data for each location is now viewable and actionable. Based on the success of these initial devices, the program will be expanded, and more sensors will be placed.

Implications for the Industry

Beyond the Middle East, early warning and detection of illegal wastewater operations is key to maintaining the integrity of treatment processes. On its own, monitoring is nice to have but it is more informative. Alongside a robust monitoring program, utility teams that are able to put the information into action—taking preventive measures in parallel—are most successful. Using the information from these water quality monitoring sensors as a tool to control gates and/or pumps, for example will make a treatment plant more resilient against unexpected pollution events.