EN Numerical modeling of a hydrocyclone in the system of technical water supply under the conditions of the UAE

Sand filters scaling by calcium carbonate precipitation during groundwater reverse osmosis desalination

Particle-scale modelling of fluid velocity distribution near the particles surface in sand filtration

The impact of rice husk, activated carbon, almond shell, and sand filters on some physical and chemical properties of aqueous salt solution

About a third of the world's population relies on groundwater for their water supply. However, in some cases, the quality of these sources is not suitable for human consumption. Reverse osmosis (RO) membrane technology is used in many cases to improve groundwater quality. Often, for effective performance of RO membranes pre-treatment of source water is required. This study aimed to assess the performance of the pre-treatment components of the brackish water RO desalination plants at the Grünau and Bethanie water supply areas. To assess the performance of the pre-treatment components at these two water supply areas, samples for water quality analyses like turbidity, fluoride, nitrate, and hardness were collected from the raw water and pre-treated water. The average removal efficiency of Bethanie’s sand filters was -2.14% for turbidity, hardness, nitrate, and fluoride. Sand filtration is a technology employed to reduce suspended solids (i.e. turbidity) and can improve microbiological quality. Sand filtration can also be used to remove precipitates formed after an oxidant was applied for example removal of iron and manganese. The negative value indicates that the sand filters were not effective in removing these contaminants, and in fact, they increased in concentration. The raw water was classified as group C, and the pre-treated water after sand filtration was group C as well. The average removal efficiency of Grünau’s sand filters was -43.28% for turbidity, hardness, nitrate, and fluoride. Again, this negative value indicates that the sand filters were not effective in removing these contaminants, and in fact, increased the concentrations. The raw water quality was classified as group D which remained as group D after sand filtration. The raw sources of water at both the treatment plants are groundwater abstracted from boreholes. This study demonstrated that the sand filters used in the pre-treatment at both plants provided minimal to no improvement in raw water quality and increased water losses through backwashing. Suspended solids and microbiological quality often do not require treatment with the use of groundwater, and therefore application of sand filtration technology as pre-treatment component not clearly justified. Therefore, future considerations regarding the use of these pre-treatment components in relation to raw water quality dynamics should be taken into account.

Recent advances in membrane technology have prompted the rapid growth of the Reverse Osmosis (RO) desalination in comparison to other water desalination technologies. One of the major problems of RO is fouling which leads to major reduction in the efficiency of this process. RO membranes are usually fouled with colloids, humic substances, micro‐organisms, and heavy metals. This is why it is critical to treat the feed water prior to RO filtration. Conventional pre‐treatment methods include processes such as coagulation, adsorption, sedimentation, flotation, sand filtration, disinfection, and the addition of anti‐scalants. Recently, membrane pre-treatment processes including micro‐filtration (MF), ultrafiltration (UF) and nanofiltration have been introduced prior to RO, with or as a replacement for conventional pre‐treatment. These processes are useful in providing feed water superior in quality to conventional pre‐treatment, but they are limited in the range of pollutant removal and operating conditions. Full description of water composition and the interactions and aggregations between the contaminants found in feed water for RO desalination is shown in this review. The review includes introduction to membranes, including retention and fouling mechanisms, conventional and membrane pre‐treatment, and membrane backwashing. It also highlights the role of coagulation and adsorption in the pre‐treatment process and the impact of integration of coagulation and/or adsorption with membrane pre‐treatment.

Sand and sand-GAC filtration technologies in removing PPCPs: A review

Cryptosporidium surrogate removal in pilot-scale rapid sand filters comprising anthracite, pumice or engineered ceramic granular media, and its correlation with turbidity

Desalination and reuse of industrial waste water by electrodialysis

Sand infiltration requires immediate action to avoid costly downhole and surface equipment erosion. Additionally, sand particles may reduce hydrocarbon production by blocking downhole fluid flow. This study demonstrates the advantage of integrating multiple reservoir monitoring logs to identify the sand contribution zones, quantify the sand production, and plan the well remediation work required, while minimizing operation downtime. A focused logging program and analysis method was developed to identify the sand infiltration location. Integration of passive acoustic and array-based production logs acquired the critical data to find the sand infiltration zones. The passive acoustic tool captured the count of inflowing sand strikes on the tool body generating a definitive acoustic signature. The array production logging tools mapped the fluid rates, flow delays, and fluid transport in the well. Post-processing of the passive acoustic data counted the unique sand strike events resulting in a quantitative sand infiltration assessment for a high deviation well penetrating Burgan and Wara reservoirs. Sand and hydrocarbon production occurred in the Burgan reservoir, while the Wara formation was initially not producing any type of fluids due to Burgan sand infiltration. Within the Burgan formation large quantities of sand were detected inside the wellbore and approximately 100 feet below the inflow location. While some sand particles circulate up-hole with the flow others settle on the bottom. Acoustic logging analysis indicated that sand infiltration was generated from the middle Burgan perforations between 5737 ft and 5742 ft. According to the production logging analysis, less than 250 STB/D Burgan oil production was only flowing from the upper-most perforations between 5714 ft and 5718 ft due to sand fill below. Remediation action focused on a cement squeeze in the middle Burgan to close the sand infiltration perforations then a subsequent re-perforation of the Wara formation to resume production in that section. The Wara formation was relogged after perforation confirming reduced sand infiltration and an oil gain of 1530 STB/D with 170 STB/D of water production. Therefore, the sand infiltration information resulted in improved remediation outcomes. The integrated measurements clearly established the impact of sand infiltration on fluid inflow and created a road map for future well monitoring improvements. This case study illustrates the successful integration of passive acoustic and array-based production logging to detect the sand infiltration zones and the high value fluid inflow zones. Well remediation activities were further optimized, re-establishing oil flow of 1530 STB/D from a set of non-producing perforations of the Wara formation.

Although many treatment methods have been employed to remove soluble Fe(II) and Mn(II) from water, for some smaller water treatment plants or under emergent circumstances such as sharp increase of iron and manganese concentrations in source water during summer, traditional physicochemical removal methods are more flexible and effective. In this article, a coupling technique of chlorine dioxide (ClO2) preoxidation and manganese sand filtration for iron and manganese removal from potable water have been proposed. Fe(II) and Mn(II) removal efficiencies of different filter materials (natural manganese sand, quartz sand, and fiber bundle filter (FBF) material) were compared. Influences of ClO2 dosage, liquid flow rate, particle size of filter material, and thickness of filter bed on removal efficiency were also examined. In addition, performance of ClO2 preoxidation–manganese sand filter technique was investigated under the optimum operating conditions to remove Fe(II) and Mn(II). Results indicated that natural manganese sand filter showed higher capability of removing Fe(II) and Mn(II) than quartz sand filter and FBF. It was found that manganese removal efficiencies increased with higher dosage of preoxidant, lower liquid flow rate, smaller sand particle diameter, and thicker filter bed. When initial concentrations of Mn(II) and Fe(II) in feed water were 1.5 and 1.0 mg/L, respectively, ClO2 dosage was 0.99 mg/L, liquid flow rate was 282.6 mL/min, sand particle diameter was 0.6–1.2 mm, and filter bed thickness was 60 cm, the process showed good performance of Fe(II) and Mn(II) removal with both removal rates more than 95%.

Performance evaluation of BWRO desalination plant — A case study

Experience with plate-and-frame ultrafiltration and hyperfiltration systems for desalination of water and purification of waste water

Hybrid membrane system for desalination and wastewater treatment : Integrating forward osmosis and low pressure reverse osmosis

While sand filters are widely used to treat drinking water, the role of sand filter associated microorganisms in water purification has not been extensively studied. In the current investigation, we integrated molecular (based on metagenomic) and physicochemical analyses to elucidate microbial community composition and function in a common sand filter used to treat groundwater for potable consumption. The results revealed that the biofilm developed rapidly within 2 days (reaching ∼1011 prokaryotes per gram) in the sand filter along with abiotic and biotic particulates accumulated in the interstitial spaces. Bacteria (up to 90%) dominated the biofilm microbial community, with Alphaproteobacteria being the most common class. Thaumarchaeota was the sole phylum of Archaea, which might be involved in ammonia oxidation. Function annotation of metagenomic datasets revealed a number of aromatic degradation pathway genes, such as aromatic oxygenase and dehydrogenase genes, in the biofilm, suggesting a significant role for microbes in the breakdown of aromatic compounds in groundwater. Simultaneous nitrification and denitrification pathways were confirmed as the primary routes of nitrogen removal. Dissolved heavy metals in groundwater, e.g. Mn2+ and As3+, might be biologically oxidized to insoluble or easily adsorbed compounds and deposited in the sand filter. Our study demonstrated that the role of the microbial community in the sand filter treatment system are critical to effective water purification in drinking water.

Chapter 7 - Conventional methods and materials used for water treatment in rural areas