The historical performance of a 1.5 mgd Memcor membrane filtration system installed in 1994 is presented. This system has continuously operated since that time. It is one of the first large scale membrane filtration systems installed in the USA as a public water system and services a private industry as well as neighboring homes. There are several ways to track the operational history of a membrane filtration system. Similar to membrane desalting technologies, operational data is normalized to monitor the permeability (or the reciprocal resistance) along with trans-membrane pressure (TMP). A description of the methods used to calculate these parameters as well as providing evaluation of the actual water system operational data is presented. Critical issues for this system were the need for frequent chemical cleaning, low efficiencies of the chemical cleanings and irreversible fouling that led to shortened membrane life. Based on the results of operational data evaluation and independent evaluations, a modified chemical cleaning procedure was initiated and pre-treatment was added to reduce the rate of irreversible fouling. Very small clay particles have been identified in the raw water from the local fractured limestone geology that is filtered by an existing Siemens’s continuous membrane filtration (CMF) system. These fine particles are fouling the microfiltration (MF) membranes shortening the useful life of the membranes and requiring frequent chemical cleanings. Polyaluminum chloride (PACl) was been selected as the desired coagulant to combine the fine clay particles into larger particles that can be easily filtered and not foul the MF membranes. Samples of five (5) different PACl solutions were tested. The value of using the PACl can be determined by both quantitative and subjective assessments. Actual operational cost savings can be calculated based on the reduction of chemicals needed for cleaning the membranes. The 5 mg/L PACl feed into the raw water line occurs just prior to entry into the raw water reservoir and shows a tremendous advantage for operation of the membrane facility.
This presentation is available to AMTA Members only.
- Mark Thompson
- Schlumberger Water Services USA, Inc.
- AMTA Annual Meeting, San Diego, CA
- San Diego Biennial
- Microfiltration, Transmembrane pressure