Modeling a way to save water

Water – hydraulic modeling – conservation – optimization are the key words that most often come up in conversations with water and sewer industry representatives in recent years, in Poland and around the world. The uncertain and often difficult situation in the energy market and tariff issues significantly affect the budgets of water and wastewater utilities, and when you add to this the instability in national and international politics, you get a scenario for very difficult times. I will try to answer the question of whether modeling and analysis can be helpful in solving current problems in the industry.

Model tools have many faces, especially in terms of managing a water and sewer enterprise and saving water as a valuable resource, but not only in terms of quantity, but also in terms of quality. With regard to the city’s water cycle, we can limit ourselves to three main areas.

First: modeling in waterworks

The basic scope of application of hydraulic models in the area of water supply networks is to calculate the flow and pressure of water in pipes. The analysis of the above results, in relation to the height of the water-supplied buildings, makes it possible to identify problem areas and, after implementing appropriate corrective measures, can result in the reduction of water losses in the network.

In the era of digitization and the ubiquity of the term “big data,” it is relatively simple to acquire data at no cost from numerical land cover models, which present the absolute height of all objects located in a given area (buildings, trees, bridges, etc.). We can model the height of each building in the study zone and compare it with the minimum absolute value of the pressure at the node from which it is fed. Such processing of the basic results makes it possible to evaluate the adopted pressure values (settings) and creates room for optimization. A pressure reduction of 2 – 3m H2O, in the case of a favorable material structure in the analyzed zone, has a measurable effect in reducing leakage.

As a side effect of the pressure setpoint adjustment made, there may be a reduction in the electricity consumption of the pumping units supplying the area.

Second: modeling – channeling

The main function of a sewage network, regardless of its type, is to transport wastewater, which is mostly a mixture of water and other substances. From the point of view of the water and sewerage company, it is important to maintain the highest possible efficiency of flows, taking into account the limits that will enable effective operation of the treatment plant and protect water quality from emergency discharges.

Hydraulic models of sewer networks, already in terms of basic simulation results (flow and filling in the collectors), allow the identification of the so-called “hydraulic models”. “bottlenecks” in the network. Their elimination translates into increased efficiency of wastewater transport. However, only a global management approach across the system will yield tangible results to protect water quality by, for example, increasing network retention and delaying runoff. The multitude of technical solutions of the retention devices themselves, the possibilities of using the existing retention of the network or trying to make assumptions related to, for example, the intensity, distribution and probability of precipitation makes the optimal selection of solutions difficult. Hydraulic models allow analysis under various scenarios, which translates into the ability to choose the optimal solution with multiple objectives in mind, including water quality protection.

The retained rainwater, given an ecological approach to its management in the city, can be used, for example, to water greenery. This saves drinking water resources, which are usually also used for gardening purposes. In the face of the water crisis and recent dry years, tools and measures to support water companies in water retention should be widespread.

Third: modeling – treatment plant

“Safe” delivery of wastewater to the treatment plant unfortunately does not yet guarantee the implementation of treatment processes with optimal parameters. Commercially available modeling tools enable advanced process analysis, optimization, and even real-time surveillance, so-called “real-time”. real-time.

Using the basic premise of modeling, that is, the ability to verify the answer to the question: what if…, we can verify the assumptions, the efficiency of the treatment process, the use of resources (dosed chemicals), the use and recovery of electricity and heat, and the response to undesirable situations in subsequent simulation attempts. Moreover, dynamic wastewater treatment processes often require critical decisions to be made at short notice. The so-called. The digital twin (digital twin) for wastewater treatment plants ultimately serves to support operator decisions by continuously analyzing sensor data and recommending optimal settings. The technology has a direct impact on efficiency in terms of the quality of water discharged into receiving bodies, and therefore also on improving environmental quality.

Protection of water resources the task of enterprises

The challenge for any water utility is to conserve water resources. With the help of modeling, we can control the circulation of water in the city from the intake (that is, from the moment it is extracted from the natural water cycle in nature) until it is returned again (after effective treatment processes have been carried out). The identification of water conservation as the main tasks of water and sewer companies and the implementation of strategies to achieve this, positively affects the economic aspects of the operation of the plants, allowing independence from political and market factors in the future.

In conclusion, undoubtedly, model analyses can be helpful in solving current problems in water and wastewater companies in many areas of their operations and existing legal and consumer obligations. For the water supply network, this is primarily the potential to reduce water and energy losses. Modeling gives the sewer network, among other things. opportunity to optimize wastewater transport, but it also allows to increase the retention capacity of urban areas and effectively manage rainwater, reducing the risk of flooding. Also in the wastewater treatment process, modeling tools successfully support the day-to-day work of wastewater treatment plant operators, optimizing processes in terms of energy and biology. These tools are becoming more widespread, and the effects of their implementation can be seen in many water and sewer companies advanced in this area.