Applicability of pebble matrix filtration for the pre-treatment of surface waters containing high turbidity and NOM

作者：Rajapakse Jay^*; Millar Graeme; Gunawardana Chandima; Roux Annalie

来源：Desalination and Water Treatment, 2016, 57(52): 24820-24832.

DOI：10.1080/19443994.2016.1149741

• Hardness
• NOM
• Pebble matrix filtration
• Pre-treatment
• Turbidity

Purification of drinking water is routinely achieved by use of conventional coagulants and disinfection procedures. However, there are instances such as flood events when the level of turbidity reaches extreme levels while natural organic matter (NOM) may be an issue throughout the year. Consequently, there is a need to develop technologies which can effectively treat water of high turbidity during flood events and NOM content year round. It was our hypothesis that pebble matrix filtration potentially offered a relatively cheap, simple and reliable means to clarify such challenging water samples. Therefore, a laboratory scale pebble matrix filter (PMF) column was used to evaluate the turbidity and NOM pre-treatment performance in relation to 2013 Brisbane River flood water. Since the high turbidity was only a seasonal and short-term problem, the general applicability of PMFs for NOM removal was also investigated. A 1.0-m-deep bed of pebbles (the matrix) partly infilled with either sand or crushed glass was tested, upon which was situated a layer of granular activated carbon. Turbidity was measured as a surrogate for suspended solids, whereas total organic carbon (TOC) and UV absorbance at 254nm were measured as surrogate parameters for NOM. Experiments using natural flood water showed that without the addition of any chemical coagulants, PMF columns achieved at least 50% turbidity reduction when the source water contained moderate hardness levels. For harder water samples, above 85% turbidity reduction was obtained. The ability to remove 50% turbidity without chemical coagulants may represent significant cost savings to water treatment plants and added environmental benefits accrue due to less sludge formation. A TOC reduction of 35-47% and UV-254nm reduction of 24-38% were also observed. In addition to turbidity removal during flood periods, the ability to remove NOM using the PMF throughout the year may have the benefit of reducing disinfection by-products formation potential and coagulant demand at water treatment plants. Final head losses were remarkably low, reaching only 11cm at a filtration velocity of 0.70m/h.

• 出版日期2016