The APEX pumps have been preferred over progressive cavity (PC) pumps in an application that sees metering of bentonite into the source water to help flocculation. Bentonite is a crystalline quartz (naturally occurring) clay product. The abrasive nature of the substance can cause costly damage to the PC pumps, a factor that is not encountered when using APEX technology.
State-owned Umgeni Water is the largest supplier of bulk potable water in the Province of KwaZulu-Natal. The organisation currently supplies 426 million cubic metres of potable water to its six municipal customers.
Conventional treatment methods for removal of suspended and colloidal material from water include chemical coagulation of small colloidal particles and flocculation of the small particles to form larger flocs or aggregates. Bentonite is added when the water to be flocculated contains too few particles for effective flocculation.
Several Umgeni Water plants have experienced difficulties with their PC pumps as a result of bentonite metering, which typically takes place around once a month on average. Upon start-up, the PC pumps will immediately run dry due to the properties of bentonite. Suction lines can sometimes become blocked and the pump stator is subject to damage.
With this in mind, the introduction of bentonite metering processes at Umgeni Water’s Amanzimtoti waterworks a short distance south of Durban, set the company thinking about alternative pump technology. After a review of the market, the pump of choice proved to be a Bredel APEX15 hose pump from Watson-Marlow.
The application at Amanzimtoti sees bags of bentonite offloaded into a 3,000 litre holding tank and then mixed. Using the Bredel APEX pump running at less than 3 bar, the abrasive liquid is then pumped so that the solids are kept in suspension. Crucially, the two APEX15 hose pumps, can be reversed if blockages are encountered, then run in the correct direction again once clear. As a result, reliability has improved significantly at the Amanzimtoti plant in the three years since the pumps have been installed
Designed to suit all metering and transfer applications from 2.8 to 6,200 litre/hr flow across a broad range of applications, APEX pumps are now a preffered choice for processing plants worldwide. Offering a robust and compact direct-coupled design, these innovative hose pumps are engineered for uptime and process continuity.
*Watson-Marlow did not do the temporary installation referred to in the article.
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