Analysis of the influence of rapid filter cycle interruption on filtrate quality

The article presents research carried out on a sand/anthracite filter in a water treatment plant in Cracow in the south of Poland. These studies show that shutting down the filter after only three hours of operation, setting it aside for four hours and restarting without backwashing did not cause any visible deterioration in the quality of the produced filtrate. Stopping the same filter for four hours, however, after 68 h of operation, visible deterioration in the quality of the filtrate can be observed. After a significant initial deterioration, the quality of the filtrate slowly improved and after a few hours, it reached a level comparable to that before the filter was taken out of service. This was probably the result of characteristic changes in shear stress at the boundary of the deposit and flowing water in the capillaries, which accompanied changes of filtration rate. Decrease in the removal efficiency of coarser particles lasted longer and was greater than that of finer particles. Decrease in particle removal efficiency after restarting the dirty filter was difficult to identify by turbidity measurements, but clearly identifiable by measuring suspended solid concentration and the number of coarser particles. Interrupting the operation of a rapid filter shortly after it has been backwashed should not significantly reduce its efficiency, but after prolonged operation, it may adversely affect the quality of the filtrate.

Increasing the energy efficiency of water inlets by re-using washed water and reducing filter cycle time

PURPOSE. The purpose of this article is to study the search for ways to reduce energy consumption and develop methods for increasing the energy efficiency of water utilities. The studies reflected in the article are based on the results of an energy survey of a water utility in the city of Gomel (Republic of Belarus), one of the tasks of which is the search for reserves for saving fuel and energy resources by reducing technological water consumption. The article presents the results of research on the example of two water intakes «Iput» and «Sozh». METHODS. When solving the problem, the methods of mathematical statistics were used, including the method of analysis of variance to assess the significance of the effect of water flushing on reducing the iron content. RESULTS. The article discusses possible ways to reduce energy costs by reducing technological water consumption, which are used to flush filtering structures. The main activities are the following: changing the filter flushing schedule with increasing the filter cycle; the use of water-air flushing; reuse of wash water. The article formulates a hypothesis: filter flushing leads to a decrease in the iron content in the water, i.e. improving the quality of cleaning. CONCLUSION. An increase in the energy efficiency of water intakes, along with measures to modernize and optimize the operation of pumping equipment, is achieved by saving water resources and, accordingly, the cost of electricity for their extraction, which is necessary when flushing the filter materials of the deferrization station. The assumption about a possible increase in the filtration cycle was the lack of significance of the influence of washing on the decrease in the iron content, which indicated the presence of a significant reserve of the washing cycle. The use of combined water and air flushing contributes to a significant reduction in both technological water consumption (40.1%) and electricity consumption (38.8%). The energy saving potential due to the reduction of technological energy consumption for lifting water for the purpose of flushing reached 89857 kWh / year for the studied water intake.

Increasing the energy efficiency of water inlets by re-using washed water and reducing filter cycle time

PURPOSE. The purpose of this article is to study the search for ways to reduce energy consumption and develop methods for increasing the energy efficiency of water utilities. The studies reflected in the article are based on the results of an energy survey of a water utility in the city of Gomel (Republic of Belarus), one of the tasks of which is the search for reserves for saving fuel and energy resources by reducing technological water consumption. The article presents the results of research on the example of two water intakes «Iput» and «Sozh». METHODS. When solving the problem, the methods of mathematical statistics were used, including the method of analysis of variance to assess the significance of the effect of water flushing on reducing the iron content. RESULTS. The article discusses possible ways to reduce energy costs by reducing technological water consumption, which are used to flush filtering structures. The main activities are the following: changing the filter flushing schedule with increasing the filter cycle; the use of water-air flushing; reuse of wash water. The article formulates a hypothesis: filter flushing leads to a decrease in the iron content in the water, i.e. improving the quality of cleaning. CONCLUSION. An increase in the energy efficiency of water intakes, along with measures to modernize and optimize the operation of pumping equipment, is achieved by saving water resources and, accordingly, the cost of electricity for their extraction, which is necessary when flushing the filter materials of the deferrization station. The assumption about a possible increase in the filtration cycle was the lack of significance of the influence of washing on the decrease in the iron content, which indicated the presence of a significant reserve of the washing cycle. The use of combined water and air flushing contributes to a significant reduction in both technological water consumption (40.1%) and electricity consumption (38.8%). The energy saving potential due to the reduction of technological energy consumption for lifting water for the purpose of flushing reached 89857 kWh / year for the studied water intake.

Optimisation of energy utilisation in Umgeni Water Works

Energy in the 21st century has been seen to escalate in cost and will continue to be one of the key cost drivers for municipalities and water utilities that operate and maintain water treatment plants. It is part of every stage of the life-cycle of water supply, i.e. abstraction, water treatment, distribution, use and disposal. Umgeni Water (UW) conducted a baseline energy assessment of eight large water works in 2013. One of the recommendations of that study was to develop an energy optimisation model that can be used for regular energy assessments by Process Engineers to improve the operational protocol as well as for input into new plant designs. A case study was conducted at a large water works which receives its raw water from two sources. The baseline energy assessment of the water works indicated that 39.9% of the total energy consumed is by the raw water abstraction works, 46.2% by the distribution pump-stations and 13.9% by the treatment works. Engineering fundamentals for an energy balance were used for the energy optimisation, where the required head was determined for the backwash pumps. An energy optimisation model for evaluating the backwash performance of a set of rapid gravity filters was developed using Artificial Neural Network (ANN) software. MATLAB ANN Simulink programme was employed to predict the optimal backwash time and filter cycle time based on using the phenomenon called feed-forward back-propagation training through its simulation. The data used to train the network consists of raw water quality data, filter run time, turbidity profiles and the final water quality data. It was seen that the MATLAB Simulink can predict the backwash time at 7% lower than the actual backwash time which is higher than the desirable 5% allowable accuracy. However, the filter cycle time was predicted at 3% higher than the actual filter run cycle time. It is concluded from this study that more backwash profiles and a larger data collection equivalent to at least six months work is required to validate this research. It was also discovered that in the presence of data that cannot be readily linked, Artificial Neural Networks can establish and clarify relationships with the different data variables. The Table 4.2 shows that indeed energy savings are possible for the operations at UW Water Works G for Filter Plant 2. The minimal amount of energy required to get the turbidity to the required specification using ANN was calculated from simulated backwash time. This lead to the average energy savings with a monetary worth only R1161.55 using power ratings on the pump while it was as high as R416 301.10 where power input calculations were used considering the head and fluid flow happening inside the pump. The filter backwash and cycle run times can be predicted and optimised to target a turbidity of less than 10 NTU, specifically 9.9 NTU as the backwash turbidity target used for the purposes of this study. Further work is recommended on gathering six months’ worth of data to further verify the model simulation results.

The Study of Possibilities for Reuse of Washings from Swimming Pool Circulation Systems

Swimming pools are very expensive, in terms of operation, sports facilities. Therefore, investors and managers of these facilities are looking for methods of reducing the costs of their use. One of the proposed methods is the managing of washings previously discharged to the sanitary sewage system. The assessment of possibilities for reuse of washings from swimming pool filtration system is based on the limits of basic indicators of pollutants in wastewater discharged to water and soil (temperature, pH, TSS, BOD5, COD, TN, TP, free chlorine). The conducted research of washings quality from 26 tested swimming pools have shown that washings quality is dependent on the operating conditions of the pool circuit, including the filter cycle duration and types of filter bed. A direct discharge to water or soil may be impossible due to excessive amounts of total suspended solids (above 35 mg/dm3) and free chlorine concentration (above 0.2 mg Cl2/dm3). However, the quality of supernatant water of washings subjected to sedimentation in the laboratory shows that the washings are suitable for reuse. The installation of settling tanks in swimming pool facilities could relieve the sewage systems and allow for the discharge of supernatant water to surface waters or for the irrigation of green areas in an environmentally friendly way.

Reduction of Cesium Radio/nuclides from Natural Waters and Liquid Radioactive Waste

Life tests on treatment with a ferrocyanidic sorbent of natural waters radioactively contaminated with 137Сs have been conducted. The sorbent’s operational characteristics have been investigated in the prolonged filter cycle mode. Assessment of the sorbent’s applicability for the cesium radio nuclides reduction in natural waters radio/chemical analysis methods has been carried out. The determined sorbent resource was 120 thousand of columnar volumes, while potential calculated resource was 400 thousand of columnar volumes. The sorbent’s effectiveness in radiochemical analysis has been proved, cesium yield was (0.97 ± 0.02) in radiochemical analysis of aquatic media.

Using turbidity and particle counts to monitor Cryptosporidium removals by filters

Physicochemical removal of protozoan pathogens is receiving increased attention because of the difficulty of chemically inactivating these organisms, particularly Cryptosporidium parvum. Most studies that have examined the removal of these and other pathogens by filtration have been conducted under steady-state conditions with optimized pre-treatment. The research on which this paper is based evaluated the removal of Cryptosporidium and surrogates at various points in the filter cycle and under non-optimal conditions, at several pilot plants. The focus of this paper is on the relationship between removals of Cryptosporidium, and turbidity and particle counts. Under stable or optimal operating conditions all pilot plants produced similar low filter effluent turbidity and particle counts. Average Cryptosporidium removal varied among locations, however, by more than two log units. Cryptosporidium removal was impaired under all of the non-optimal conditions. Particle and turbidity performance was also worse, but the relationship of these parameters to Cryptosporidium removal varied. Particle counts show greater promise than turbidity as a tool to monitor filter performance in real time for possible deterioration in Cryptosporidium removal capability.