Removal of cyanobacteria by slow sand filtration for drinking water

2012 ◽  
Vol 2 (3) ◽  
pp. 133-145 ◽  
Author(s):  
Silvano Porto Pereira ◽  
Fabiana de Cerqueira Martins ◽  
Lenora Nunes Ludolf Gomes ◽  
Manoel do Vale Sales ◽  
Valter Lúcio De Pádua
Keyword(s):  
Water Treatment ◽  
Rural Communities ◽  
Human Consumption ◽  
Industrialized Countries ◽  
Sand Filtration ◽  
Intact Cells ◽  
Slow Sand Filtration ◽  
Treatment Techniques ◽  
Slow Sand Filter ◽  
The City

Potential problems arising from the presence of cyanobacteria in water intended for human consumption have been reported by several researchers. Regarding water treatment plants, intact cells of cyanobacteria should be removed to avoid the release of cyanotoxins due to cell lysis. Water treatment techniques with different degrees of complexity can be employed but, whenever possible, the method of easiest installation, operation and maintenance should be selected, especially for non-industrialized countries and rural communities. In this context, research was carried out to evaluate the efficiency of slow sand filtration to treat water from Gavião reservoir in the city of Pacatuba, Ceara, Brazil, which has exhibited phytoplankton density of approximately 105 cells/mL with a prevalence of cyanobacteria representing over 90% of total cells. The results have demonstrated that slow sand filtration can be used to achieve water purification that meets federal standards. However, it was established that filtration through beds of gravel (prefilter) before the slow sand filtration is essential. The removal of phytoplankton reached values of approximately 97% and the filter run duration was more than 70 days. Furthermore, the slow sand filter was very efficient in removing total coliforms, with removal of up to 99.98%.

scholarly journals Natural organic matter removal by ion exchange at different positions in the drinking water treatment lane

2013 ◽  
Vol 6 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. Grefte ◽  
M. Dignum ◽  
E. R. Cornelissen ◽  
L. C. Rietveld
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Organic Matter ◽  
Water Treatment ◽  
Organic Carbon ◽  
Natural Organic Matter ◽  
Drinking Water Treatment ◽  
Biological Stability ◽  
Sand Filtration ◽  
Slow Sand Filtration

Abstract. To guarantee a good water quality at the customers tap, natural organic matter (NOM) should be (partly) removed during drinking water treatment. The objective of this research was to improve the biological stability of the produced water by incorporating anion exchange (IEX) for NOM removal. Different placement positions of IEX in the treatment lane (IEX positioned before coagulation, before ozonation or after slow sand filtration) and two IEX configurations (MIEX® and fluidized IEX (FIX)) were compared on water quality as well as costs. For this purpose the pre-treatment plant at Loenderveen and production plant Weesperkarspel of Waternet were used as a case study. Both, MIEX® and FIX were able to remove NOM (mainly the HS fraction) to a high extent. NOM removal can be done efficiently before ozonation and after slow sand filtration. The biological stability, in terms of assimilable organic carbon, biofilm formation rate and dissolved organic carbon, was improved by incorporating IEX for NOM removal. The operational costs were assumed to be directly dependent of the NOM removal rate and determined the difference between the IEX positions. The total costs for IEX for the three positions were approximately equal (0.0631 € m−3), however the savings on following treatment processes caused a cost reduction for the IEX positions before coagulation and before ozonation compared to IEX positioned after slow sand filtration. IEX positioned before ozonation was most cost effective and improved the biological stability of the treated water.

Elimination of terpenoid odorous compounds by slow sand and river bank filtration of the Ruhr River, Germany

1995 ◽  
Vol 31 (11) ◽  
pp. 211-217 ◽  
Author(s):  
F. Jüttner
Keyword(s):  
Bank Filtration ◽  
Sand Filtration ◽  
Sand Filters ◽  
Slow Sand Filtration ◽  
River Bank ◽  
Lipophilic Compounds ◽  
Slow Sand Filter ◽  
Odorous Compounds ◽  
Aliphatic And Aromatic Hydrocarbons ◽  
River Bank Filtration

The elimination of odorous compounds by river bank and slow sand filtration was studied at the Ruhr River in Germany. The aquifer of the river bank filtration was anoxic and exhibited intense dissimilatory nitrate reduction; the aquifer of the slow sand filter was oxic. Polar monoterpenes, such as linalool, menthol, isobornyl acetate, lipoxygenase products (oct-1-en-3-ol) and geosmin exhibited a much higher percentage elimination than monoterpene hydrocarbons and other lipophilic compounds (dimethyldisulphide, aliphatic and aromatic hydrocarbons). The efficiency of river bank filtration was slightly better than that of slow sand filtration. The schmutzdecke and upper layers of the slow sand filters were responsible for most of the removal of VOC. The deeper layers exhibited only small effects.

Water treatment for rural areas by slow sand filtration

2010 ◽  
Author(s):  
Bruno Segalla Pizzolatti ◽  
Marcus Bruno Domingues Soares ◽  
Denise Conceição de Gois Santos Michelan ◽  
Luis Romero Esquivel ◽  
Maurício Luiz Sens
Keyword(s):  
Water Treatment ◽  
Rural Areas ◽  
Sand Filtration ◽  
Slow Sand Filtration

Chemically enhanced gravel pre-filtration for slow sand filters: advantages and pitfalls

2006 ◽  
Vol 6 (1) ◽  
pp. 121-128
Author(s):  
C.C. Dorea ◽  
B.A. Clarke
Keyword(s):  
Negative Impact ◽  
Pilot Scale ◽  
Sand Filtration ◽  
Sand Filters ◽  
Slow Sand Filtration ◽  
Chemical Enhancement ◽  
Dissolved Organics ◽  
Efficiency And Effectiveness ◽  
Slow Sand Filter ◽  
Pre Treatment

The chemical enhancement of gravel (or roughing) filtration with coagulants, i.e. direct (gravel) filtration, has been proposed as a pre-treatment alternative for slow sand filters. However, studies have frequently focused on the efficiencies of the pre-filters in terms of reduction percentages. The effectiveness of the pre-treatment on the subsequent slow sand filtration is not usually cited or even evaluated. By incorporating a pilot-scale slow sand filter in our trials, both aspects of the pre-treatment process were assessed: efficiency and effectiveness. In terms of turbidity reductions, our results demonstrated that chemically enhanced pre-filtration was substantially more efficient (93.2 to 99.5%) than conventional pre-filtration (50.6 to 79.3); this was also observed in terms of reductions in the level of other parameters (i.e. thermotolerant faecal coliforms and dissolved organics). Yet, the use of a coagulant can have a negative impact on the slow sand filtration run.

Removal of bisphenols by slow sand filtration

2009 ◽  
Vol 9 (3) ◽  
pp. 263-268 ◽  
Author(s):  
K. Katayama-Hirayama ◽  
S. Arai ◽  
T. Kobayashi ◽  
H. Matsuda ◽  
Z. Luo ◽  
...  
Keyword(s):  
Removal Rate ◽  
Molecular Orbital Calculation ◽  
Photocatalytic Reaction ◽  
Sand Filtration ◽  
Removal Rates ◽  
Sand Filter ◽  
Slow Sand Filtration ◽  
Initial Concentration ◽  
Slow Sand Filter ◽  
High Removal Rate

A compensating effect in the reduction of bisphenols (BPs) has been shown using biodegradation in slow sand filtration and advanced photocatalysis. We tried to remove 8 kinds of BP by slow sand filtration. Removal rates of BPA, BPB, BPE, BPF, BPS, thiobisphenol (TBP), and dihydroxybenzophenone (DHB) indicated a high removal rate up to more than 90% at an initial concentration of 100 μg/L, whereas the removal rate of BPP was only 30%. We also examined removal of BPs by Pt-loaded porous photocatalyst under visible light irradiation. Removal rates of BPA, BPB, BPE, BPF, BPP, and TBP showed high removal rates up to more than 90% at an initial concentration of 10 mg/L. Removal of BPS and DHB was relatively low at 20% and 30%, respectively. Removal of BPP was low in slow sand filtration, but Pt-loaded photocatalyst removed BPP effectively. Removal of BPS was low with Pt-loaded photocatalyst, but slow sand filtration removed BPS effectively. The combination of a slow sand filter and Pt-loaded photocatalyst may be helpful to degrade BPs. The magnitude of decomposition of BPs by photocatalytic reaction may be related to electrophilic frontier density. But the degradability of BPs in slow sand filtration is not the same as that in photocatalytic reaction with Pt-loaded titanium dioxide. The biodegradability of BPs by slow sand filtration cannot be explained by molecular orbital calculation.

scholarly journals Applying Bio-Slow Sand Filtration for Water Treatment

2019 ◽  
Vol 28 (4) ◽  
pp. 2243-2251 ◽  
Author(s):  
Laisheng Liu ◽  
Yicheng Fu ◽  
Qingyong Wei ◽  
Qiaomei Liu ◽  
Leixiang Wu ◽  
...  
Keyword(s):  
Water Treatment ◽  
Sand Filtration ◽  
Slow Sand Filtration
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