Particle size distribution in an efluent from an advanced primary treatment and its removal during filtration

1997 ◽  
Vol 36 (4) ◽  
pp. 159-165 ◽  
Author(s):  
H. Landa ◽  
A. Capella ◽  
B. Jiménez
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Primary Treatment ◽  
Suspended Solid ◽  
Sand Filters ◽  
Related Information ◽  
Solids Concentration ◽  
Operating Rate ◽  
Suspended Solid Concentration

The filtration efficiency of an Advanced Primary Treatment System (APT) was analyzed in terms of suspended solids concentration, particle size distribution and helminth eggs counts. A study was carried out on three one-metre deep sand filters with a specific size (ES) of 0.6, 0.8 and 1.2 mm. More than 50 runs were done with operating rate of 7, 10, 12 and 15 m/h. Basic design-related information was obtained for the APT system. A filter with a 1.2 mm ES provided the best effluent, with 0.1 Helminth egg/L. The average suspended solid concentration in the effluent was 39 mg/L. The most recommendable filtration rate was 10 m/h with a run time of 33 h. A study of the particle distribution was made for each step of the process based on size.

Tertiary filtration in small wastewater treatment plants

2007 ◽  
Vol 55 (7) ◽  
pp. 219-225 ◽  
Author(s):  
V. Naddeo ◽  
V. Belgiorno
Keyword(s):  
Particle Size ◽  
Wastewater Treatment ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Wastewater Treatment Plants ◽  
Rotating Disk ◽  
Quality Parameters ◽  
Particle Removal ◽  
Sand Filters ◽  
Filter Performance

Tertiary filtration can be proposed in small wastewater treatment plants with impact on protected water bodies. Rotating disk filters may be adopted, in respect to conventional sand filters, when low availability of space and low investment costs are the prevailing conditions. The overall objective of this research was to evaluate the filtration efficiency of rotating disk filters; to compare effectiveness with traditional sand filters; to analyse thoroughly the importance of particle size distribution in wastewater tertiary filtration. In the experimental activity, conventional wastewater quality parameters were investigated and particle size distribution (PSD) was characterized to discuss the filter effectiveness. The effect of design and operation parameters of tertiary filters were discussed related to particle removal curves derived from particles counts. Analysis of particle size distribution can be very useful to help comprehension of filtration processes, design of filtration treatments and to decide the best measures to improve filter performance.

scholarly journals CFD simulation of solids suspension in stirred tanks: Review

2010 ◽  
Vol 64 (5) ◽  
pp. 365-374 ◽  
Author(s):  
Aoyi Ochieng ◽  
Mrice Onyango
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Concentration Distribution ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Cfd Modeling ◽  
Small Scale ◽  
Stirred Tanks ◽  
Solids Concentration

Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD) techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.

Particle size distribution to design and operate an APT process for agricultural wastewater reuse

2006 ◽  
Vol 53 (7) ◽  
pp. 43-49 ◽  
Author(s):  
A. Chavez ◽  
C. Maya ◽  
B. Jimenez
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Contact Time ◽  
High Performance ◽  
Wastewater Reuse ◽  
Primary Treatment ◽  
Operating Conditions ◽  
High Rate ◽  
Treatment Objective

Total suspended solids is a parameter commonly used to operate and design coagulation–flocculation processes. Nevertheless, their application for an advanced primary treatment (a high performance but low dose demand coagulation processes coupled with a high rate sedimentator, sometimes called enhanced primary treatment) is not the best option to produce an effluent for agricultural irrigation. This paper compares the best operating conditions obtained using the TSS or the PSD (particle size distribution) as parameters to follow the efficiency. The treatment objective was to remove particles >20 μm, in such conditions that the effluent can contain organic matter and nutrients necessary for crops with a reduced number of helminth ova (with sizes between 20 to 80 μm). Using the TSS as parameter, the best coagulation (460 s−1, 60 s contact time and 300 μmolAl/L) and flocculation (20 s−1 with 15 min) conditions produced an effluent with 1.2 HO/L. To obtain a similar results but using operating conditions determined with the PSD at a three times lower coagulant dose can be employed (diminishing operating costs and reducing the quantity of sludge produced), and a reduction on energy consumption of around eight times can be reached. Best operating conditions defined using the PSD (160 s−1, 60 s contact time and 100 μmolAl/L) produced an effluent with <0.4 HO/L.

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