Water Hardness Research Articles

Hydrochemical analysis of surface water quality dynamics in the Oskil river

Purpose. Hydrochemical analysis of the dynamics of changes in the quality of surface waters of the Oskil River. Methods. Comparison of hydrochemical indicators with norms of maximum permissible concentrations (MPC). To determine the water quality criterion, the MPC for fisheries reservoirs was taken. The general assessment of water quality is determined by the following methods: water pollution index (WPI), modified WPI and specific combinatorial water pollution index (WPI). Results Based on the water pollution index, it was determined that the river corresponds to the category "very clean" to "moderately polluted". The water pollution index of the Oskil River indicates that the upper course corresponds to the II class "clean", but near the city of Kupyansk the water quality deteriorates to the III class "moderately polluted", and further downstream it again becomes the II class "clean".. According to the methodology specific combinatory water pollution index, the river water is rated from "very clean" to "moderately polluted". The pH in the water varied from 6.08 to 9.27. The total water hardness varied between 10.0 and 2.8 mmol/dm3. The oxygen level indicates an acceptable water condition in most areas. Compounds, the concentration of which most often exceeds the MPC for all observation posts, are: chromium 6+, manganese, copper, petroleum products. Other compounds may also exceed the MAC in some posts and observation years, including total iron, sulfates, zinc 2+ , nitrites, cobalt, phenols, and BSC5. Conclusions. Significant variations in the concentrations of chemical elements in different areas were found in the water quality of the Oskil River. Index of water pollution of the Oskil River according to the calculations of the IZV mod. shows that in most cases for all years of observation, the river corresponds to the III class "moderately polluted". The change in the KIZ indicator along the Oskil River shows that the level of pollution of the river is low along its entire length and it mostly remains under the influence of insignificant anthropogenic influence.

Frictional properties of red pine cones harvested under different conditions

The climbing of trees to pick pinecones is a high-risk exercise. In this study, a mechanical gripper jaw was designed. Frictional characteristics between the pinecones and the mechanical gripper jaw during pinecone picking under different conditions were investigated using a workbench simulation, homemade inclined friction meter, and mass tester. Three-level orthogonal and one-factor tests were conducted. The relationship between the water content and friction properties and between the water content and hardness were investigated, and conclusions were drawn on how water content affected friction properties by influencing hardness. The results showed that the contact material greatly affected the friction properties. The pinecone water content was maintained between 24% and 28% to ensure that the coefficient of friction was maximized and that the pinecones were sufficiently hard to dislodge. Additionally, a prototype machine was used to perform pinecone-gripping experiments to validate the experimental and simulation results. Consequently, the results of this study provide a useful reference for the structural design of pinecone picking robots and the picking reason.

Influence of cooking water hardness on the chemical, colour and textural characteristics of bulgur at different processing stages

The hardness of water is important for food quality where it is used as a direct ingredient in production, thus it is a very critical parameter for the texture and colour of bulgur as it is used in the cooking operation. In line with this fact, the effects of water with 3 different hardness (soft, hard and very hard) on the proximate composition, functional properties, mineral composition, colour, texture, thermal, structural and sensory characteristics in wheat, cooked wheat and after drying, debranning and milling stages of wheat (fine bulgur) were investigated. Production of bulgur with very hard water contributes to the retention of minerals in the structure of wheat and therefore the bulgur produced. Water hardness negatively affected the antioxidant activity of wheat samples after cooking and the drying, debranning and milling stages. Colour and sensory analysis proved that cooking with very hard water has a reducing influence on the yellowness of bulgur which causes a production defect. Based on the obtained results, it is recommended to use soft water in bulgur production as cooking with very hard water influences the functional and sensory properties of the product adversely.

A Comprehensive Study of Variation in Water Quality Parameters to Design a Sustainable Treatment Plant

In this paper, greywater samples are collected from the kitchens of different types of buildings (residential and commercial) located in different districts within the city of Jeddah, Saudi Arabia. The collected samples are analyzed and compared with the potable water from the same region. The parameters investigated are pH, conductivity, total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), total hardness, temporary hardness, permanent hardness, alkalinity, chloride, and biochemical oxygen demand (BOD). It was found that the amount of total suspended solids is very high in the greywater samples. It shows the presence of both temporary and permanent hardness. Their alkalinity values are greater than hardness. It may be due to the number, lifestyle, age of the occupants, presence of children, and social and cultural behavior of residents. The concentration of BOD level is very low, which shows that the greywater samples have lower concentrations of organic compounds. Design details of the greywater treatment plant are suggested based on the results of the analysis. This includes a screening chamber, grit chamber, settling tank, and filtration unit. The treated greywater is recommended for reuse for gardening, landscaping, and toilet flushing purposes.

Reagentless reduction of hydrogen carbonate-calcium hardness of water: equilibrium states and kinetics

The equilibrium states and kinetics of changes in the concentrations of carbonate system components in water with different calcium hardness are analyzed and the possibility of reducing this indicator by an environmentally friendly method, aeration, is evaluated. Changes in the concentrations of dissolved carbon dioxide, calcium ions, hydrogen ions (pH), bicarbonate and carbonate ions in water depending on the partial pressure of carbon dioxide in soil and atmospheric air and the kinetics of reducing the bicarbonate-calcium hardness of water during its natural and forced aeration were traced. It is shown that water purification by a stream of atmospheric air microbubbles with an average radius of 50 m and a flow rate of 10 l/min can reduce the hydrogen carbonate-calcium hardness from 8 mg-eq/l to 1 mg-eq/l in 100 liters of water in 20 minutes. In the paradigm of "green chemistry", this method is more rational, environmentally friendly, and economical than ion exchange or reverse osmosis, which are currently practiced to reduce hardness in decentralized water supply systems.

Modelling the pesticide transfer during tea and herbal tea infusions by the identification of critical infusion parameters.

Pesticide residues in tea and herbal tea often exceed EU maximum residue limits. Consideration of the transfer of pesticides from the leaves (called transfer factors) to the brew is essential to assess the associated risk. This study identified infusion parameters influencing the transfer behaviour of 61 pesticides and elaborated a predictive model for pesticides with unknown transfer factors in black, green, herbal and flavoured teas. Tea type and the presence of flavours were the criteria that most influenced the pesticide transfer. Interestingly, infusion parameters that are individual and area dependent such as infusion time, temperature and water hardness, did not play a significant role. Beta regression models developed to characterise pesticide behaviour during infusion showed good predictions for most pesticides and revealed that log (P) was the main physico-chemical parameter to estimate the pesticide transfer. The transfer factors database and validated models are valuable tools for improving risk assessment.

Growth Performance of <i>Salmostoma bacaila</i> in Biofloc System

The present research work was study on the growth performance of Salmophasia bacaila in the biofloc culture system for the period of 28 days from the second week of September to second week of October 2022.The initial weight of fingerlings of the Salmophasia bacaila were 0.667 gm and cultured for 28 days in the experimental tanks at30 fish/tank. The experiment was designed in two tanks, one tank was used as control, while the other tank was used as biofloc treatment tank. The mean value of water temperature, pH, dissolved oxygen, water hardness, alkalinity in biofloc treatment system were 24.6℃, 7.9, 4.88mg/l, 128.14mg/l and 124.42mg/l respectively. The control set registered the mean value of water temperature 23.5℃, pH 8.6, dissolved oxygen 5.1mg/l, hardness 123.50mg/l& alkalinity 118.66mg/l. The SGR was 1.97observed in biofloc treatment while in control tank the same was1.73. 77% survival rate of fishes were registered in the under biofloc treatment and 73% in the control tank.

Challenges Ahead in Groundwater of Sri Lanka

Groundwater has been a safe water storage in Sri Lanka throughout history and the unique characteristics of different aquifers impact variation of the water quality. However, due to population growth, unplanned urbanization, intensive agriculture, improper waste management, etc., the groundwater quality is considered unsafe. Therefore, it is important to refer to the available data related to the groundwater quality of Sri Lanka. Saltwater intrusion is a considerable factor in shallow karstic aquifers and as a result, relatively higher electrical conductivity, water hardness, total alkalinity, and higher anions concentrations (chloride, sulfate) were observed in the Jaffna area. The dry zone including Padaviya and Hambanthota shows relatively higher water hardness and fluoride in groundwater. Nitrate concentration is also a considerable factor, especially in the Jaffna and Padaviya areas may be due to intensive agriculture. Identification of groundwater recharge zones, recharge estimates, continuous monitoring of groundwater quality, vulnerability mapping of aquifers, and proper planning of urbanization have been identified as challenges ahead in groundwater of Sri Lanka and it is essential to include those items in the National Water Policy in Sri Lanka.

STUDY OF THE EFFICIENCY OF USING THE EXPERIMENTAL BIOCIDE SANDEZ FOR THE SANITATION OF THE POULTRY WATER SUPPLY SYSTEM

Ensuring the maximum level of biosecurity in farms that grow poultry without the use of antibiotics is a prerequisite for epizootic well-being. The article presents data on the development of an ecologically safe method of sanitation treatment of the water supply system of poultry houses. For sanitation treatment of the water supply system, the alkaline detergent and disinfectant "Sandez" was used, which is an aqueous solution of alkali, does not contain anti-corrosion substances and compounds that create a potential threat of negative impact on the environment. The active substance of the drug "Sandez" - sodium hydroxide causes denaturation of protoplasmic proteins of microbial cells. In the experiment, the water supply system of the poultry house was filled with a 1.5% solution of "Sandez" disinfectant and left filled with this solution for after standing for 1 hour, the aqueous solution was drained and the pipelines were washed with clean tap water. In the control, sodium hypochlorite with a concentration of 75–100 mg/dm3 of active chlorine was used to disinfect the water supply network. Environmentally safe disinfectant "Sandez" ensures compliance of water quality and safety indicators with the requirements of state sanitary standards and regulations. "Sandez" product has an excellent washing effect with water hardness up to 8 mg-eq/l, has a low corrosive effect on metal structures of technological equipment. The method of sanitation treatment of the water supply network of poultry houses in the system of veterinary and sanitary measures during poultry farming is based on the use of a 1.5% solution of the ecologically safe alkaline detergent and disinfectant "Sandez" has high disinfectant properties, provides a bactericidal effect on pathogenic microorganisms E. coli, S. enteritidis, Enterococcus spp., P. aeruginosa, microbial contamination is 24% less than a similar pokahnik in the control control.The use of this method in the system of veterinary and sanitary measures during poultry farming provides a high sanitizing effect, control of microbiological indicators of the safety of drinking water, a long-lasting antiseptic effect, prevents the emergence of resistance of microorganisms to the action of disinfectants and does not create a negative impact on the environment.

Preparation of water swellable rubber from epoxidized natural rubber and sodium acrylate by in‐situ polymerization: Effect of vulcanization system, epoxide, and dicumyl peroxide, and sodium acrylate content

AbstractWater swellable rubber (WSR) was prepared from epoxidized natural rubber (ENR) and sodium acrylate (NaAA) by in‐situ polymerization using sulfur and dicumyl peroxide (DCP) as a vulcanizing agent and an initiator, respectively. The ENR, NaAA, and other additives were mixed in an internal mixer and a two‐roll mill. The effect of the vulcanization system, epoxide, and DCP, and NaAA content on the vulcanization, physical, and mechanical properties of WSR were investigated in this research. As the results, the scorch and curing time of WSR compounded with ENR 25 and vulcanized with a mixture of sulfur‐peroxided or mixed vulcanization system were less than other systems. Furthermore, the scorch and curing time decreased with the increase in DCP content. The WSR with ENR 50 vulcanized with DCP (1.5 phr) in the mixing system provided the highest tensile strength. However, the volume change of WSR with the mixing system (WSR/M) was lower than the WSR cured with peroxide (WSR/P). For WSR/P, the tensile strength, hardness, and volume change in water increased with increasing DCP, and NaAA content, while the elongation at break decreased. These results suggest that WSR has the potential for diverse applications, including waterproofing and sealing solutions in civil construction projects.Highlights Water swellable rubber (WSR) was prepared from epoxidized natural rubber (ENR) and sodium acrylate (NaAA) by in‐situ polymerization using sulfur and dicumyl peroxide (DCP) as a vulcanizing agent and an initiator. The scorch and curing time of WSR compounded with ENR 25 and vulcanized with a mixed vulcanization system were less than those of other systems. During the vulcanization process, ENR 50 can be generated by the ring‐opening of the adjacent epoxide groups more than ENR 25, and the self‐crosslink of ENR 50 was higher than ENR 25. Water swelling and volume change of WSR tended to decrease with increasing epoxide, and DCP content, whereas those properties increased with increasing NaAA content. Tensile strength, elongation at break, and hardness of WSR with the mixing system (WSR/M) were higher than those of WSR with the peroxide system (WSR/P). Swelling and volume change of WSR/P were higher than those of WSR/M.

Development of Eco-Friendly Method for Degumming of Eri Cocoons

In this study, a new eco-friendly degumming technique was developed for Eri cocoons without any chemicals. A newly developed eco-Eri degumming process was tried at 110 °C, 120 °C, 130 °C and 140 °C temperatures for 10, 20 and 30 min with soft and hard water. The novel eco-friendly degumming method was compared with the existing method of degumming viz. Soap-soda along with the enzymatic method. After degumming, weight loss per cent, changes in the fibre surface morphology concerning SEM imaging and fibre properties concerning tensile strength and elongation were studied. The eco-Eri degumming method at 130 °C for 30 min using soft water removed the maximum sericin content (degumming loss 15.7%) from Eri cocoon shells and had optimum degumming efficiency. In the eco-Eri degumming method, the degummed Eri cocoons were uniformly softened. The soap soda method of degumming resulted in 14.5% weight loss whereas enzymatic degumming resulted in a maximum of 13% weight loss (12% dosage). Enzymatic degumming significantly reduced the tensile strength but no results found in the tensile properties of Eri silk fibres were observed in new eco-friendly and soap-soda methods. SEM images indicated optimal fibre surface with the smoother surface until 130 °C, but fibre damage and fibrillation occurred at 140 °C and also with the Soap-soda method. An optimal condition for degumming Eri cocoons with the new eco-Eri degumming process is 130 °C for 30 min using soft water. The eco-Eri degumming method is better compared to other methods used presently in the industry.

Methodology of elastic full‐waveform inversion of multicomponent ocean‐bottom data for anisotropic media

AbstractFull‐waveform inversion of multicomponent data can provide an improved estimation of medium parameters using both compressional‐ and shear‐wave information. However, most earlier studies that involved a full‐waveform inversion of ocean‐bottom data are based on acoustic anisotropic or elastic isotropic approximations. Here, we consider realistic elastic anisotropic media and develop an efficient full‐waveform inversion framework for estimating model parameters. We simulate seismic wavefields using a previously developed coupled acoustic/elastic wave propagator that implements a mimetic finite‐difference method with fully staggered grids to accurately handle the fluid/solid boundary conditions. The algorithm employs a multiscale approach starting from low frequencies and incorporating higher frequency bands in the later inversion stages. We analyse the influence of different types of input data on the accuracy of the inverted anisotropy parameters for hard and soft water bottoms. The employed misfit function incorporates information from both hydrophones and ocean‐bottom geophones. Numerical examples indicate that injecting multiple data components simultaneously increases the complexity of the objective function and often degrades the quality of the estimated medium parameters. Thus, we propose a sequential strategy using a single data component at a time. Pressure (hydrophone) data alone can provide satisfactory results if long offsets (i.e., with the offset/depth ratio ≥ 3) are available. Adding the horizontal particle‐displacement or ‐velocity components increases the accuracy of the estimated shear‐wave vertical velocity () and P‐wave normal‐moveout () velocity, especially for strongly heterogeneous sub‐water‐bottom models.

Development and optimization of an extruded aquafeed formulated with moringa flour as a partial substitute for sardine meal

ABSTRACT This study aimed to optimize an extruded aquafeed for Oreochromis niloticus (Nile tilapia) using moringa as a partial protein source. Response surface methodology (RSM) with a Rotatable Central Composite Design (CCRD) was employed to evaluate the four factors influence: sardine meal (28.5–39.25%), moringa flour (34.85–45.60%), temperature (110–140°C) and moisture content (13–17%) on aquafeed’s physicochemical characteristics: expansion index (EI), bulk density, water solubility index (WSI), water absorption index (WAI), hardness and buoyancy. Numerical optimization identified 100 potential diets, of which four were selected and met the criteria for high WSI (11–14%), low hardness (22–32 N) and 100% buoyancy. The best diet consisted of 31.19% sardine meal and 42.91% moringa flour, processed at 132.5°C and 16% moisture, presenting 13.68% WSI, full buoyancy, 29.63 N hardness, 36.33% protein, 10.71% lipids, and 31.36% carbohydrates, applicable to fingerling O. niloticus.

Water Physico-Chemical Indicators and Metal Assessment of Teceu Lake and the Adjacent Groundwater Located in a Natura 2000 Protected Area, NW of Romania

This study closely analyzes the water quality dynamics of Teceu Lake, situated in a Natura 2000 protected area in Romania. The research investigates seasonal variations and interconnections with groundwater, assessing various ecological impacts. The main physico-chemical indicators of water, such as electrical conductivity (EC), dissolved oxygen (DO), oxygen saturation (OS), temperature, pH, turbidity, ammonium concentration (NH4+), nitrates (NO3−), nitrites (NO2−), orthophosphates (PO43−), water hardness, alkalinity (A), and chlorides (Cl−), were measured over the January–December 2022 period. Metal concentrations for both major metals (Na, K, Ca, Mg, Al) and trace metals (Li, Ga, Fe, Mn, Pb, Cu, Zn, Ni, Ti, Mo, Sr, Ba) were assessed. The evolution of the physico-chemical indicators revealed an increase in nutrient compounds (ammonium and phosphates) during the spring and autumn months. The EC values ranged from 180–444 μS/cm for the lake and 1575–2480 μS/cm for groundwater. The pH values (7.12–7.96) indicated a slightly alkaline environment. DO levels (6.79–11.21 mg/L) indicated good water quality. Chlorides exceeded levels in drinking water in some instances. Water hardness varied due to pH, temperature, and atmospheric pressure. Metal composition revealed diverse levels of aluminum, barium, nickel, copper, zinc, and manganese, which carries implications for environmental and human health. The water quality index (WQI) score, which is based on major ions, indicated that 93% of the groundwater samples were classified as excellent and good for drinking. WQI, based on the main physico-chemical indicators, revealed that 79.17% of the Teceu Lake-water samples and 41.66% of the groundwater samples gathered were classified as good quality; the difference indicated poor quality, especially in autumn. Q- and R-mode cluster analyses revealed distinct clusters for seasonal months and sampling points, suggesting shared sources and geological influences. Notable connections between physico-chemical indicators and metal content were identified, emphasizing the need for a tailored conservation strategy. Correlation analyses highlighted both positive and negative relationships between metal pairs. Understanding these parameters is vital for water resource management and preserving biodiversity in the region. The results of this study are important for monitoring pollution in Lake Teceu and might prompt local communities and authorities to take measures to reduce and prevent pollution.

Improvement of heat transfer and fouling retardation performance of heat exchanger using green functionalized graphene nanoplatelets additives

BackgroundCalcium carbonate (CaCO3) is one of the main fouling elements of the crystallization fouling that causes critical problems in the operation of industrial heat exchangers. This study presents the retardation of CaCO3 Fouling, and heat transfer enhancement of a tube heat exchanger immersed in a CaCO3 rich solution containing clove treated graphene nano platelets (C-GNP) additives as suspension. MethodsThermo-physical properties of water-based C-GNP additives nanofluid were tested before running the experiment. Experimental investigation was conducted to assess the C-GNP additives performance in the enhancement of heat transfer and reduction of fouling deposition. For the retardation of fouling experiments, the hard water or super saturated fouling solution of 300 ± 20 mgL−1 was prepared. To maintain the hard water concentration until the end of the experiments, a complexometric titration was adopted to monitor the CaCO3 concentration at every 6 h. interval. The FESEM was utilized for the investigation of the morphology of CaCO3 deposition on the heat exchanger surface. Significant findingsThe results of this study demonstrate that the addition of C-GNP enhanced the heat transfer and reduced the foulant deposition without any effect of corrosion. The results also revealed the inverse relationship between the additive concentration and the fouling resistance. The outcomes of this study also support the achievement of United Nation sustainable development goal (SDG) target 7.3.

Ultrasound-modified whey protein-enriched instant noodles: Enhancement in functional, rheological, cooking, and structural attributes.

Instant noodles enriched with ultrasound-modified whey protein (WP) were characterized for physical, technological, rheological, cooking, thermal, invitro protein digestibility (IVPD), morphological, and sensory attributes to access the compatibility of ultrasound for actual food matrix. Semolina with sonicated WP (SWP) showed significantly (p < .05) higher water absorption capacity (1.586 g/g) than semolina with raw WP (1.512 g/g). Semolina with SWP also showed a significantly higher water solubility index, oil binding, and firmer gel, even at 5% concentration. The addition of SWP positively impacted pasting properties and improved dough handling, as also supported by the constantly increasing storage (G') and loss (G″) modulus. SWP significantly decreased the cooking loss (7.48%) and considerably increased cooking weight (13.80%), water uptake ratio (14.35%), noodle diameter, expansion (4.47%), hardness, springiness, gumminess, and chewiness of instant noodles. Thus, the instant noodles containing SWP imparted high resistance to tear and wear to noodle strands. The improved thermal, IVPD (90.46%), and acceptability with excellent structural (morphology) integrity authenticate SWP as a quality protein source for enrichment.

Influence of Water Quality and Pollution on Broiler’s Performance, Vaccine and Antibiotic Efficiencies – A Review

Abstract Good water quality for livestock is critical for preserving animal health, ensuring the quality of animal products, supplying safe food, and increasing food production economics. Higher water levels of toxic compounds than permitted can impair meat, fat, eggs, and milk production, lower fertility, and represent public health hazards. Water picks up pollutants from its surroundings and those caused by animal and human activities. Many physicochemical parameters were used to ensure water quality, including pH, salt, taste, color, alkalinity, odor, and hardness. Water quality, directly and indirectly, impacts livestock performance and, thus, the poultry industry. Employing drinking water as a carrier of drugs still faces substantial barriers. The effectiveness of vaccinations and drugs is affected by inadequate water quality. Furthermore, contaminated water and poor nutrition negatively affect broiler chicken immunity, survival, and production. Antibiotics are widely utilized in poultry production to preserve animal health and growth. They can eliminate harmful bacteria in the gut, reduce the load on the immune system, optimize the digestive system, and boost growth performance. However, the abuse of antibiotics in animal agriculture has resulted in antibiotic-resistant infections threatening people and animals. As a result of its positive impact on the metabolome and gut microbiome, the natural antimicrobial combination could be used as an alternative; improving broiler chicken growth performance without negatively affecting the environment is currently paramount.

Pemanfaatan Sumber Daya Desa Dengan Pelatihan Pembuatan Sabun Deterjen Cair Berbasis Industri Rumah Tangga

Utilization of village resources is an effort to develop the independence and welfare of rural communities by increasing knowledge, attitudes, skills, behavior, abilities, awareness, and utilizing resources through establishing policies, programs, activities and assistance that are in accordance with the essence of the problems and priority needs of the village community . The direction of community empowerment in general stems from two main objectives, namely releasing the shackles of poverty and underdevelopment and strengthening the position of the community in the power structure. Compared to the previous product, namely soap, detergent has the advantage of having better washing powder and not being affected by water hardness. In practice, many laundry services use detergents as washing agents because detergents have effective cleaning properties compared to ordinary soap.

Potential of Citronella Oil and Gum Rosin as Antimicrobial Agents in Floor Cleaner Liquid Against Salmonella thypi

Some floor cleaner products on the market contain antimicrobial agents that are harmful to humans and the environment, such as benzalkonium chloride. Therefore, searching for a new antimicrobial agent that is relatively safe is a significant challenge. In this study, we investigated the best formula for making floor cleaner using citronella oil and gum rosin as antimicrobial agents. Its antimicrobial activity against Salmonella thypi was investigated and compared with that of a commercial floor cleaner containing benzalkonium chloride. Five concentrations and ratios of citronella oil and gum rosin were investigated. The quality of floor cleaner in terms of pH range and the stability of the emulsion in hard water was assessed according to SNI 06-1842-1995. The results showed that all formulas met the pH range required by SNI, except for formulas containing citronella oil alone. The emulsion in hard water was stable for all formulas. The antimicrobial activity increased with increasing concentrations of antimicrobial agents. Citronella oil exhibited higher antimicrobial activity than gum rosin. Benzalkonium chloride showed higher microbial activity than gum rosin but lower than citronella oil. The combination of citronella oil and gum rosin showed higher microbial activity by 1.1–2.4 times than formulas containing benzalkonium chloride. The optimum floor cleaner formula (a concentration of citronella oil and gum rosin of 2% with a ratio of 1:1) has an inhibition zone diameter of 22.2 mm.

Long-term operation optimization of circulating cooling water systems under fouling conditions

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating water system (CCWS) by depositing ions on the heat exchanger's surface. Currently, the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption, without considering fouling. However, low flow velocity promotes fouling. Therefore, it’s crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation. This study proposes a mixed-integer nonlinear programming (MINLP) model to achieve this goal. The model considers fouling in the pipeline, dynamic concentration cycle, and variable frequency drive to optimize the synergy between heat transfer, pressure drop, and fouling. By optimizing the concentration cycle of the CCWS, water conservation and fouling control can be achieved. The model can obtain the optimal operating parameters for different operation intervals, including the number of pumps, frequency, and valve local resistance coefficient. Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases, the marginal benefits of energy/water conservation decrease. In periods with minimal impact on fouling rate, energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate. Overall, the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.