Water is crucial for life. Not only is it crucial to human health, but it also provides vital ecosystem habitats for fish and is essential for crops and livestock. Water plays a large role in the recreation industry, with many activities relying on the cleanliness and safety of natural recreational water facilities, be they lakes, rivers or beaches. Wastewater monitoring ensures that treated water released back into the environment does not cause damage to this precious resource.
Xylem has a history as a trusted partner of both the municipal and industrial wastewater industry, providing something much more valuable than just monitoring equipment and systems to ensure reliable plant operation and compliance: expertise.
A deep and comprehensive understanding of the processes used from inlet to plant through to final discharge enables Xylem to consider a holistic approach to the plant, incorporating not only discharge compliance and isolated process basics but both energy and manpower efficiencies.
Effective and efficient control is not possible without a full understanding of process performance and changes in load. This understanding cannot be reached without accurate monitoring of key parameters throughout the process. The accuracy of the measurements cannot be assumed, but required validation. Xylem is able to provide the full suite of instrumentation and knowledge to ensure that all of the needs listed above are met.
In many wastewater treatment plants, a large percentage of the energy budget is consumed in processes requiring aeration, for example activated sludge processing plants. Such plants treat wastewater in a biological manner, i.e. both aerobically and anaerobically to break down the ammonia content into nitrate and, ultimately, nitrogen.
Typically, these plants are controlled based on a dissolved oxygen setpoint alone based on single measurements within each treatment lane. This prevents the plant from effectively reacting to changes in load, resulting in either expensive over-aeration or discharge consent failure and hydrogen sulphide production due to under-aeration.
WTW IQ SensorNet range of sensors
By monitoring the influent ammonia and mixed liquor suspended solids (MLSS), as well as the process dissolved oxygen (DO) levels and nitrate levels within the plant, the blowers can be controlled in real time to ensure the optimum oxygen level is identified and delivered for the condition of the process liquor currently being treated.
The IQ SensorNet system has been developed with the both accuracy and operator efficiency in mind. The removal of wipers in favour of integral ultrasonic cleaning within the MLSS sensor for example means there are no blades or seals to replace, no moving parts to foul and no paths of water ingress should a seal be replaced improperly. Similar thought has been applied to Xylem's optical DO sensor the FDO. By mounting the membrane at 45 degrees the potential for a flat surface to catch bubbles and sludge and hence produce false readings is greatly reduced. This again reduces the frequency with which an operator will need to inspect and clean the sensor - a fact borne out through our experiences across the world.
Alongside Ammonia, additional compounds and elements are also heavily regulated at the point of discharge. Phosphorous can lead to the eutrophication of waterways; this causes algae to form and the bacteria within the algae use up the oxygen within the water, leaving it depleted for fish and other wildlife.
Phosphorous removal is often carried out by precipitation: a coagulant is mixed with the wastewater (often calcium, aluminium or iron based) to precipitate the phosphorous. The use of chemicals in this process is costly both in terms of shipment and carbon footprint; the chemicals themselves are hazardous and require careful handling and over-use of the chemicals results in increased sludge volumes which require additional transport and treatment alongside running the risk of carry-over of the chemical into discharge. It is therefore very important to be able to accurately dose the coagulant based on the load within the process.
The self-calibrating Xylem P 700 IQ, part of the IQ SensorNet range, can be installed directly on to a handrail and can cope with all weather conditions, whilst also being compact and is designed to use a fraction of the reagent typically required for wet chemistry analysis. This enables phosphorous measurements to be made more frequently allowing a more complete understanding of plant function and better control of chemical dosing, another example of Xylem's drive for both accuracy and operator efficiency.
The WTW IQ SenorNet range is modular in construction. Sensors and control units may be installed around a large site and can be connected to each other to form a single network, either through our advanced cabling or multi-hub wireless. The full range of communication protocols are available for communication back into the site control system: the classic analogue and relay combination, Profibus, Modbus, Ethernet etc. Should the communications requirements change at a site using the SensorNet, the network can remain in place. Only the communications modules need to be exchanged to go from analogue to Profibus. This helps to simplify network upgrades thereby reducing downtime and cost to the user.
Environmental Responsibility and Accountability
Regulatory compliance is becoming increasingly tightly policed across the globe and providing samples of wastewater at both influent and effluent to a treatment plant is critical in demonstrating compliance, both during internal audits and in routine inspections.
There are requirements within the wastewater industries to not only sample and monitor effluent parameters but also to produce, on demand, discharge monitoring reports. Such reports should illustrate compliance with effluent discharge parameters and proper operation and function of the plant (through monitoring of process data), and there should also be a log of any emergency operations carried out or failures of the plant. Such reports will indicate not only effluent parameters but also discharge flow rates with date and time stamps.
The ProSample range of sampling equipment offers fully automated portable sampling units. They are lightweight and easy to use, even in inconvenient spaces around the plant. The peristaltic pump, incorporated in the units, allows highly accurate sampling based on time, flow or event. In such a regulation-driven environment, traceability and accountability are high priorities.
The Storm package from Xylem allows data from the data loggers to be transferred to the Storm Central cloud data network. From here the client, or Xylem support staff, can log in and track data from the system. The data can also be downloaded for subsequent investigations, trending and producing compliance reports. Continuous online monitoring of effluent quality allows the operator to control the treatment plant so that it meets compliance targets, or to shut down the plant should a fault occur.
Your Partner in Compliance
In the interests of protecting the precious resource of water, both as an ecosystem habitat and as a crucial element to life, monitoring of wastewater allows industries to prevent unintentional discharges that could damage ecosystems and the native species living there. After all the reuse of water is something that we all must consider, it being an increasingly sought after resource.
Unregulated non-compliant discharges could lead to contaminated water making its way into irrigation systems and water supplies used for washing and watering livestock and, eventually, into the human food chain.
It is the responsibility of plant operators and managers to ensure that they are doing all they can to protect and preserve this crucial commodity. Xylem products and services provide operators with modern, flexible, reliable and easy-to-use tools to fulfil these responsibilities and to operate their plants at optimum efficiency and efficacy.