Nutrient conditions and reactor configuration influence floc size distribution and settling properties

2012 ◽  
Vol 65 (1) ◽  
pp. 156-163 ◽  
Author(s):  
G. A. C. Ehlers ◽  
D. Wagachchi ◽  
S. J. Turner
Keyword(s):  
Size Distribution ◽  
Nutrient Concentrations ◽  
Size Analysis ◽  
Liquid Separation ◽  
Floc Size ◽  
Treatment Processes ◽  
Floc Size Distributions ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Nutrient Conditions

Floc formation and settleability is critical for effective solid–liquid separation in many wastewater treatment processes. This study aimed to investigate the relationship between particle size distribution and nutrient conditions in different bioreactor configurations. Size distribution profiles of flocs that formed in continuous (B1), continuous with clarifier and return sludge (B2) and SBR (B3) reactors were investigated in parallel under identical nutrient conditions. An eight-fold dilution of the influent COD of a synthetic dairy processing wastewater resulted in a ‘feast and famine’ regime that triggered significant effects on the biomass and flocculation characteristics. Floc size analysis of reactor MLSS revealed a shift in floc sizes when reactors were fed with the minimum (famine) COD wastewater feed (0.61 g L−1). Increasing floc size distributions were detected for all reactors during the minimum COD feed although different size patterns were observed for different reactor configurations. These increases corresponded with variations in aggregation and EPS quantities. The SBR yielded comparatively larger flocs when operated under both COD feeds as indicated by d(0.9) values (90% of particles ≤ d in size). Overall the results indicated that floc formation and floc size are mediated by nutrient concentrations and represents an important step towards improved solid–liquid separation.

The Effect of Operational Factors on Solid/Liquid Separation by Ultra-Membrane Filtration in a Biological Denitrification System for Collected Human Excreta Treatment Plants

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1583-1590 ◽  
Author(s):  
Y. Magara ◽  
M. Itoh
Keyword(s):  
Membrane Filtration ◽  
Suspended Solids ◽  
Permeation Flux ◽  
Filtration Process ◽  
Liquid Separation ◽  
Human Excreta ◽  
Treatment Processes ◽  
Solids Concentration ◽  
Solid Liquid ◽  
Solid Liquid Separation

One third of the total population of Japan is served by collected human excreta treatment systems for the sanitary treatment of human wastes. In order to cope with the stringent effluent quality regulations set for human excreta treatment plants, the high-load biological denitrification process with ultra-membrane filtration for solid/liquid separation has been recently developed. This system has big advantages not only with respect to the solid/liquid separation stage of biological treatment processes, but also as regards the cost and operational effectiveness of advanced treatment processes such as ozonation and activated carbon adsorption. However, problems can be experienced with the ultra-membrane filtration process because the attainable hydraulic load is completely governed by the permeation flux. Therefore, in order to utilized the ultra-membrane filtration process in a biological wastewater treatment system, the effects of the operational factors on the permeation flux have to be clarified. In this paper, the effects of factors such as water temperature, suspended solids concentration, driving pressure, and water velocity in the unit are described. It has become clear that in order to attain a stable permeation flux, the water temperature and suspended solids concentration should be kept as stable as possible. The results of the investigation of the development of cake or gel layer resistance showed that high pressure and high velocity give a high and stable permeation flux. However, it has also been shown that the optimum operational conditions are high pressure and low velocity, due to the energy costs for operation of the system.

scholarly journals Determination of Size Distribution of Precipitation Aggregates Using Non-Invasive Microscopy and Semiautomated Image Processing and Analysis

2019 ◽  
Author(s):  
Michelle Quilaqueo ◽  
Minghai Gim-Krumm ◽  
René Ruby-Figueroa ◽  
Elizabeth Troncoso ◽  
Humberto Estay
Keyword(s):  
Image Processing ◽  
Particle Size ◽  
Size Distribution ◽  
Laser Diffraction ◽  
Aggregation Behavior ◽  
Liquid Separation ◽  
Image Processing And Analysis ◽  
Non Invasive ◽  
Solid Liquid ◽  
Solid Liquid Separation

Precipitation processes are technologies commonly used in hydrometallurgical plants to recover metals or to treat wastewaters. Moreover, solid-liquid separation technologies, such as thickening or filtering, are relevant unit operations, included in the precipitation technologies. These methods are strongly dependent on the characteristics of the solid precipitates formed during the specific precipitation reaction. One of these characteristics is the particle size distribution (PSD) of the solid precipitates which are fed into a solid-liquid separation process. Therefore, PSD determination is a typical practice for the characterization of the slurries generated in a precipitation plant. Furthermore, the precipitates generated in these processes have a colloidal or aggregation behavior, depending on the operational conditions. Nevertheless, the conventional methods used to estimate PSD (e.g., laser diffraction and/or ciclosizer) have not been designed to measure particles that tend to aggregate or disaggregate, since they include external forces (e.g., centrifugal, agitation, pumping and sonication). These forces affect the true size of the aggregates formed in a unit operation, thereby losing representativity in terms of aggregates particle size. This study presents an alternative method of measuring the size distribution of particles with aggregation behavior, particularly, by using non-invasive microscopy and image processing and analysis. The samples used have been obtained from an experimental precipitation process by applying sulfidization to treat the cyanide-copper complexes contained in a cyanidation solution. This method has been validated with statistical tools and compared with a conventional analysis based on laser diffraction. Our results show significant differences between the methods analyzed, demonstrating that image processing and analysis by microscopy is an excellent and non-invasive alternative to obtaining size distribution of aggregates in precipitation processes.

Intensification of solid–liquid separation by thermal sedimentation in pressure oxidative leaching process of chromite

2021 ◽  
Vol 164 ◽  
pp. 106825
Author(s):  
Xiaoyu Tang ◽  
Shihao He ◽  
Facheng Qiu ◽  
Xianfeng Qin ◽  
Xuejun Quan ◽  
...  
Keyword(s):  
Liquid Separation ◽  
Leaching Process ◽  
Oxidative Leaching ◽  
Solid Liquid ◽  
Solid Liquid Separation

<i>Evaluation of Mechanical Scraper System Finishing Barn for Solid-Liquid Separation</i>

2017 ◽  
Author(s):  
Joshua Tyler Brown ◽  
Teng Teeh Lim ◽  
Joseph Zulovich ◽  
Christine Costello
Keyword(s):  
Liquid Separation ◽  
Solid Liquid ◽  
Solid Liquid Separation
Sign in / Sign up

Export Citation Format

Share Document