This study investigated the impact of conventional pre-treatment on the fouling potential of
seawater. The conventional treatment train consisted of coagulation (ferric chloride as the
coagulant) followed by rapid dual media filtration (sand/anthracite). The impact of post-chlorination
(sodium hypochlorite) was also studied. Laboratory experiments were carried out on
Atlantic Ocean seawater and some pilot tests were performed on Mediterranean Sea water.
Several parameters were monitored both in raw and treated waters including total organic
carbon, total nitrogen and phytoplankton pigments (HPLC analysis). Microorganisms
(picophytoplanktonic cells and bacteria) were also analyzed by flow cytometry. Residual
oxidant and trihalomethanes were analyzed in the chlorinated water as a function of time.
Membrane fouling tests were performed on the pretreated waters using a cellulose regenerated
ultrafiltration membrane (MWCO 100 kDa) in dead-end mode. Results showed that about
of the micro-organism population were removed by coagulation and dual media
filtration. On the contrary, total organic carbon (TOC) and TN removals were almost insignificant. The influence of
coagulant dose and pH studied during pilot scale experiments showed minor effect of
coagulant dose and higher microorganism and particle removal at low pH (pH 5.9). The
membrane fouling potential was significantly reduced after direct filtration. The addition of
chlorine (sodium hypochlorite) led to the formation of bromoform as the dominant trihalomethane (THM) byproduct.
Our results showed that THM precursors were significantly reduced after direct
filtration. Also, post chlorination slightly reduced ultrafiltration (UF) membrane fouling and eliminated the
remaining picophytoplanktonic cells. Includes 7 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 480 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 03/01/2005 |
