Water Research Foundation Report
2 total works
Optimising Filtration Processes through Online Floc Particle Characterization
by Joerg E. Drewes, T. Ingels, G. Yates, A. Beierle, R Crittenden, and V. Jones
Published 15 February 2008
This report will be available as a Pay-Per-View item only.
The quantitative analysis of floc particles either on- or offline is not widely used in the operations of surface water plants, which use granular media filtration. Floc particle analysis is defined as photographically analyzing the floc for cross sectional area, diameter, and particle count. Several technologies are commercially available for accomplishing this task, yet little has been done in the way of investigating the possibility of improving water quality and plant operations with these measurements. Considering that flocculation will continue to be a key process in water treatment, it is worthwhile to improve the consistency and quality of treated water, ensuring public health and operational consistency for years to come. The objectives of this project were to establish and demonstrate the benefit of floc particle measurements both at bench- and full-scale operations at surface water treatment plants.
The researchers planned to demonstrate the following two main hypotheses on pilot- and full-scale:
Findings of this study demonstrated that bench-scale floc particle diameter analysis predicts granular media filtration particle removal on pilot scale. This is true primarily for the charge neutral mechanism, usually employed in direct filtration and DAF. The charge neutral floc particles predicted filtration particle removal much more sensitively than sweep floc particles. This was due to the nature of sweep floc and enmeshment of hydroxide flocs. In situ floc particle analysis showed high sensitivity to process and chemical changes. The floc particles were monitored on pilot scale on a limited basis during sweep floc conditions. The floc particles indicated large differences in floc characteristics depending upon hydrolyzing metal salt (HMS) dosage. In addition, the online floc particle measurement at pilot-scale was sensitive to the addition of floc-aid polymer at very low doses of 0.3 mg/L. Floc particle analysis at full-scale was carried out at three different treatment plants that use different unit processes. Granular media filtration employed at the three facilities was a combination of anthracite and sand. The City of Golden uses conventional treatment with coagulation-flocculation-sedimentation-filtration. The City of Boulder uses dissolved air flotation (DAF) instead of sedimentation. The Utah Valley Water Plant employs direct filtration.
The quantitative analysis of floc particles either on- or offline is not widely used in the operations of surface water plants, which use granular media filtration. Floc particle analysis is defined as photographically analyzing the floc for cross sectional area, diameter, and particle count. Several technologies are commercially available for accomplishing this task, yet little has been done in the way of investigating the possibility of improving water quality and plant operations with these measurements. Considering that flocculation will continue to be a key process in water treatment, it is worthwhile to improve the consistency and quality of treated water, ensuring public health and operational consistency for years to come. The objectives of this project were to establish and demonstrate the benefit of floc particle measurements both at bench- and full-scale operations at surface water treatment plants.
The researchers planned to demonstrate the following two main hypotheses on pilot- and full-scale:
- Bench floc particle analysis predicts filtration particle removal
- In situ floc particle analysis is a sensitive measure of process performance
Findings of this study demonstrated that bench-scale floc particle diameter analysis predicts granular media filtration particle removal on pilot scale. This is true primarily for the charge neutral mechanism, usually employed in direct filtration and DAF. The charge neutral floc particles predicted filtration particle removal much more sensitively than sweep floc particles. This was due to the nature of sweep floc and enmeshment of hydroxide flocs. In situ floc particle analysis showed high sensitivity to process and chemical changes. The floc particles were monitored on pilot scale on a limited basis during sweep floc conditions. The floc particles indicated large differences in floc characteristics depending upon hydrolyzing metal salt (HMS) dosage. In addition, the online floc particle measurement at pilot-scale was sensitive to the addition of floc-aid polymer at very low doses of 0.3 mg/L. Floc particle analysis at full-scale was carried out at three different treatment plants that use different unit processes. Granular media filtration employed at the three facilities was a combination of anthracite and sand. The City of Golden uses conventional treatment with coagulation-flocculation-sedimentation-filtration. The City of Boulder uses dissolved air flotation (DAF) instead of sedimentation. The Utah Valley Water Plant employs direct filtration.
Over the past decade, EDCs and PPCPs have become a major issue for drinking water utilities. The public, scientists, and regulators all have begun actively investigating this issue, and utilities are often tasked with addressing and communicating complex and sometime conflicting scientific data. In recent times, many utilities have been faced with difficult requests from the community regarding occurrence, treatment, and health relevance data.
This report serves to provide utilities with summary data useful in addressing these requests. The objective of this project was to develop a concise review on the state of knowledge of endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) in drinking water so water utilities can communicate with customers and make internal decisions on monitoring and treatment options.
The purpose of the guide was to summarize the history, analytical methods, bioassays, occurrence, health relevance, and communication issues regarding endocrine disruptors and pharmaceuticals. Literature regarding EDCs and PPCPs in water was evaluated for applicability to drinking water utilities. Suitable data was determined by publication in peer-reviewed literature, data from within the research team and funding agency, and through suggestions from the Project Advisory Committee. It was not feasible, nor particularly useful, to review every chemical that could be considered a suspected EDC or a PPCP. Therefore, a subset of chemicals was chosen that are representative of the subclasses and types of EDCs and PPCPs that are of current scientific and public interest. The wealth of data evaluated was summarized into succinct chapters that provide the key findings of the review, while providing references for those who seek detailed information.
This report serves to provide utilities with summary data useful in addressing these requests. The objective of this project was to develop a concise review on the state of knowledge of endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) in drinking water so water utilities can communicate with customers and make internal decisions on monitoring and treatment options.
The purpose of the guide was to summarize the history, analytical methods, bioassays, occurrence, health relevance, and communication issues regarding endocrine disruptors and pharmaceuticals. Literature regarding EDCs and PPCPs in water was evaluated for applicability to drinking water utilities. Suitable data was determined by publication in peer-reviewed literature, data from within the research team and funding agency, and through suggestions from the Project Advisory Committee. It was not feasible, nor particularly useful, to review every chemical that could be considered a suspected EDC or a PPCP. Therefore, a subset of chemicals was chosen that are representative of the subclasses and types of EDCs and PPCPs that are of current scientific and public interest. The wealth of data evaluated was summarized into succinct chapters that provide the key findings of the review, while providing references for those who seek detailed information.