scholarly journals Zero emission technology of excess sludge. A case of water treatment without generation of excess sludge by multistage contact filter bed method.

1999 ◽  
Vol 28 (8) ◽  
pp. 543-546 ◽  
Author(s):  
Masahiko NIHEI
Keyword(s):  
Water Treatment ◽  
Excess Sludge ◽  
Zero Emission ◽  
Filter Bed

Solid-Liquid Separation Process: Modelling for Design and Development of Gravity Deep-Bed Filters for Water Treatment

2007 ◽  
Vol 18-19 ◽  
pp. 563-568
Author(s):  
O.E. Ekenta ◽  
B.U. Anyata
Keyword(s):  
Water Treatment ◽  
Dynamic Models ◽  
Design Development ◽  
Quality Model ◽  
Depth Filtration ◽  
Using Data ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Development And Management ◽  
Filter Bed

This work focuses on the conception and formulation of appropriate filtration models for use by water treatment professionals for design, development and management of deep-bed (depth) filters. Performance and optimization studies were carried out using data (turbidity, filtration rate, head loss) acquired from pilot filter test runs. The curves developed from these studies were utilized for the formulation of steady-state and hydro-dynamic models of depth filtration. An effluent quality model was developed, relating depth of flow in filter bed with effluent turbidity. This model was verified and validated. The depths obtained are in good agreement with standard values from literature.

A novel acoustic imaging tool for monitoring the state of rapid sand filters

2013 ◽  
Vol 14 (1) ◽  
pp. 107-118
Author(s):  
Nihed Allouche ◽  
Dick G. Simons ◽  
Paul Keijzer ◽  
Luuk C. Rietveld ◽  
Joost Kappelhof
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Acoustic Waves ◽  
Vertical Direction ◽  
Drinking Water Treatment ◽  
The State ◽  
Acoustic Response ◽  
Sand Filters ◽  
Cleaning Procedure ◽  
Filter Bed

A new technology based on acoustic waves is developed to monitor the state of sand filters used in drinking water treatment. Changes in the sand filter, due to the removal of suspended particles from the water and their accumulation in the pores, result in an increase of the bulk density and acoustic speed of the granular material. Consequently, the reflected acoustic response changes as the filter is in use. To monitor these changes, an instrument composed of an omnidirectional transmitter and an array of hydrophones was built. With frequencies ranging between 10 and 110 kHz, high resolution is achieved in the vertical direction enabling the detectability of clogged layers with a minimum thickness of 1 cm. The novel instrument is tested by conducting a monitoring experiment in a filter used in practice. A 2D scan over a part of the filter was performed and repeated every 2 hours over a period of 10 days. An analysis of the data revealed a local increase of the reflected acoustic response with increasing filter run time. The changes in acoustic signal are mainly observed at the upper 5 cm of the sand bed. It is also clear that the filter bed is slowly compacting as a function of time. The total compaction after a period of 10 days reached 3.5 cm. The filter bed is expanded again during the cleaning procedure. Once the procedure is completed, the upper 30 cm of the filter becomes more transparent, showing small accumulations of material at greater depth. The observed changes in the filter bed demonstrate the potential of this acoustic-based tool to monitor the state of rapid sand filters and optimise their performance. The new tool can be used to evaluate the cleaning procedure and is valuable in detecting lateral variations in the filter bed. These variations may indicate local clogging that needs to be removed effectively to avoid deterioration of the overall performance in the long term. This type of information is difficult to obtain from the monitoring techniques currently used in drinking water treatment.

The application of new technologies in the water treatment process of a modern waterworks

2002 ◽  
Vol 2 (1) ◽  
pp. 63-69 ◽  
Author(s):  
O. Hoyer ◽  
J. Clasen
Keyword(s):  
Water Treatment ◽  
High Speed ◽  
High Performance ◽  
Treatment Process ◽  
New Technologies ◽  
Water Treatment Process ◽  
Lime Water ◽  
Aggregation Step ◽  
The Individual ◽  
Filter Bed

The new plant for the treatment of water from the Wahnbach-reservoir went into operation at Siegburg, Germany in 2001. It will have a capacity of 3,600 to 4,800 m3/h and is intended for drinking water supply of the Bonn region. The relatively simple water treatment process achieves its high performance and safety from the sophisticated process layout and control developed from 40 years of research and experience at the Wahnbach Reservoir Association. According to temporal needs permanganate and/or powdered activated carbon can be applied for pretreatment. Flocculation is either possible with Al3+- or Fe3+-salt solutions introduced by optimized flash-mixing and destabilization. Immediately afterwards at the inlet into the 12 aggregation and filtration trains it is possible to inactivate motile planktonic organisms by means of cavitation fields generated by ultrasound at 40 kHz. In the following aggregation step flocs are generated tailored to optimum retention in the double media filters which are regenerated via high speed build-up backwashing. Release of plankton and microorganisms accumulated in the filter bed by motile plankton is inhibited by the ultrasound treatment. A continuously high filtrate quality is achieved by stacked filter-runs of the 12 filters adapted to the water quality with backwashes graded at equal time intervals after identical filter-run times, a filter to waste period after backwash first filtrate separation and permanent turbidity monitoring at the individual filtrate outlets. Disinfection is achieved with 3 closed UV-systems equipped, performance tested and certified according to the DVGW technical standard W 294 and is followed by conventional. de-acidification with addition of lime water. The paper will describe and explain the process concept which has been worked out and validated by WTV within the framework of several research projects.

Disinfection by-products and microbial contamination in the treatment of pool water with granular activated carbon

2005 ◽  
Vol 52 (8) ◽  
pp. 71-76 ◽  
Author(s):  
W. Uhl ◽  
C. Hartmann
Keyword(s):  
Activated Carbon ◽  
Water Treatment ◽  
Organic Carbon ◽  
Disinfection Byproducts ◽  
Free Chlorine ◽  
Swimming Pool ◽  
Pool Water ◽  
Swimming Pool Water ◽  
Removal Efficiencies ◽  
Filter Bed

For swimming pools, it is generally agreed that free chlorine levels have to be maintained to guarantee adequate disinfection. Recommended free chlorine levels can vary between 0.3 and 0.6mg/L in Germany and up to 3mg/L in other countries. Bathers introduce considerable amounts of organic matter, mainly in the form of such as urine and sweat, into the pool water. As a consequence, disinfection byproducts (DBPs) are formed. Regulations in Germany recommend levels of combined chlorine of less than 0.2mg/L and levels of trihalomethanes (THMs) of less than 20μg/L. Haloacetic acids (HAAs), haloacetonitriles (HANs), chloropicrin and chloral hydrate are also detected in considerable amounts. However, these compounds are not regulated yet. Swimming pool staff and swimmers, especially athletes, are primarily exposed to these byproducts by inhalation and/or dermal uptake. In Germany, new regulations for swimming pool water treatment generally require the use of activated carbon. In this project, three different types of granular activated carbon (GAC) (one standard GAC, two catalytic GACs) are compared for their long time behaviour in pool water treatment. In a pilot plant operated with real swimming pool water, production and removal of disinfection byproducts (THMs, HAAs, AOXs), of biodegradable substances (AOC), of bacteria (Pseudomonas aeruginosa, Legionella, coliforms, HPC) as well as the removal of chlorine and chloramines are monitored as function of GAC bed depth. Combined chlorine penetrates deeper in the filter bed than free chlorine does. However, both, free and combined chlorine removal efficiencies decrease over the time of filter operation. The decreases of removal efficiencies are also observed for parameters such as dissolved organic carbon, spectral absorption coefficient, adsorbable organic carbon and most of the disinfection byproducts. However, THMs, especially chloroform are produced in the filter bed. The GAC beds were contaminated microbially, especially with P. aeruginosa. The contamination was not removable by backwashing with chlorine concentrations up to 2mg/l free chlorine.

scholarly journals Improving Filtrate Quality Using Agrobased Materials as Coagulant Aid

2002 ◽  
Vol 37 (4) ◽  
pp. 745-756 ◽  
Author(s):  
Pramod Kumar Raghuwanshi ◽  
Monika Mandloi ◽  
Arvind J. Sharma ◽  
Hanumat S. Malviya ◽  
Sanjeev Chaudhari
Keyword(s):  
Water Quality ◽  
Water Treatment ◽  
Granular Media ◽  
Moringa Oleifera ◽  
Head Loss ◽  
Turbid Water ◽  
Filter Performance ◽  
Treatment Train ◽  
Strychnos Potatorum ◽  
Filter Bed

Abstract In the present study, an evaluation of agrobased materials (ABM) as a coagulant aid in conjunction with alum has been conducted to determine their efficacy in water treatment. The agrobased materials evaluated are Surjana seed (Moringa oleifera), Nirmali seed (Strychnos potatorum) and maize (Zeemays). Experiments have been conducted simulating a conventional water treatment train consisting of coagulation-flocculation-settling and granular media filtration. Emphasis has been given to the filtration aspect of the treatment train using synthetic turbid water. The filter performance was defined by water quality and head loss development across the filter bed. When Nirmali seed or maize was used as a coagulant aid, the alum dose required was 25 and 15 mg/L, respectively, and the filtrate turbidity achieved was less than 0.2 NTU, whereas alum alone with a dose of 45 mg/L achieved filtrate turbidity levels higher than 1 NTU. Thus, the use of ABM improved the filtrate quality. Head loss in filter with Surjana seed and Maize as coagulant aids was comparable to that of alum alone, whereas it was higher when Nirmali seed was used as a coagulant aid.

Operational aspects on foaming in digesters caused by microthrix parvicella

1998 ◽  
Vol 38 (8-9) ◽  
pp. 29-34 ◽  
Author(s):  
Åsa Dillner Westlund ◽  
Eva Hagland ◽  
Maria Rothman
Keyword(s):  
Waste Water ◽  
Water Treatment ◽  
Activated Sludge ◽  
Gas Phase ◽  
Waste Water Treatment ◽  
Gas Bubbles ◽  
Excess Sludge ◽  
Water Treatment Plants ◽  
Microthrix Parvicella ◽  
Operational Aspects

Foaming in the digesters has been observed several times at three large waste water treatment plants in Stockholm, Sweden. The foam is caused by the filamentous organism Microthrix parvicella, a hydrophobic filament which traps the gas bubbles and creates a foam. The foam in the digesters causes economical loss and a security hazard. Different solutions to prevent problems with foaming has been tried and applied. By increasing the sludge load in the biological stage the growth of Microthrix parvicella can be reduced. Decreasing the sludge level in the digesters or installing mixers in the gas phase can prevent the foam from blocking the gas pipe. Heating (70°C, 5 min) the excess sludge has in lab scale been shown to change the foam potential of activated sludge with a high content of Microthrix parvicella and could be used as a solution to prevent foaming.

Sign in / Sign up

Export Citation Format

Share Document