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Water Efficiency
Published in Steve Doty, Commercial Energy Auditing, 2020
The potential for fouling can be predicted by specific water testing techniques which are mentioned here for completeness, but not fully described Silt fouling potential is indicated by a high SDI value, (silt density index.) SDI is determined by flowing water through a 0.45 micron membrane and measuring pressure drop accumulation. Most if not all membrane manufacturers list maximum SDI of <5.Scaling potential is determined by detailed water analysis and concentration, (recovery rate.) This is the Langeliers saturation index, (LSI.) LSI determines how high of a recovery can be achieved without reaching the point of saturation for any of the ions. LSI takes into account temperature and pH.
Desalination
Published in Frank R. Spellman, Hydraulic Fracturing Wastewater, 2017
The silt density index (SDI) is a dimensionless value resulting from an empirical test used to measure the level of suspended and colloidal material in water. It is calculated from the time it takes to filter 500 mL of the test water through a 0.45-µm pore diameter filter at 30 psi pressure at the beginning and at the end of a specified test duration. The lower the SDI, the lower the potential for fouling a membrane with suspended solids. Visually, the deposited foulant on a filter membrane can be identified by its color. For example, foulant that is yellow could possibly indicate iron or organics, red foulant indicates iron, and black may indicate manganese (Kucera, 2010).
Membranes
Published in Tadahiro Ohmi, Ultraclean Technology Handbook, 2017
Norihisa Urai, Hiroaki Ishikawa, Koichi Sawada
The SDI (silt density index) is generally used to monitor RO feedwater quality. The SDI is given as the percentage of filter clogging per minute, which corresponds to the lowering of the filtering speed when water is passed through a 0.45 μm membrane filter at constant pressure.
Environmental risk assessment of harmful algal blooms case study: Persian Gulf and Oman Sea located at Hormozgan Province, Iran
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Zohreh Gholami, Mohammad Seddiq Mortazavi, Abdolreza Karbassi
If the Feed water has silt density index (SDI) of more than 5 (SDI >5), it will lead to disrupt in the membrane of the reverse osmosis (RO) in this facility (Berktay 2011; Richlen et al.2010). Exploitation and overuse of groundwater resources in Iran over the past three decades, especially in the southern regions of the country, including Hormozgan province, has caused many aquifers in these areas to face serious problems with fresh water supply.