Internship in Nestlé - 25th Jan 2017 (8am - 5pm)

At 9.15 a.m., we had a daily review meeting with the operators.

At 9.30 a.m., Fam asked me to help him generate several adhesive stickers of black words with yellow background to label the chemical dosing systems in the WWTP. It was my first time using the label dispenser in a technical store.

At 12.00 p.m., Fam shared some ideas with me about the working principles and theories behind the DAF process. He told me that only certain suitable size of air bubbles is generated and attached to the solids to allow the solid floatation before being scrapped off at the water surface. Besides that, there are several DAF process arrangements and operating conditions.

At 2.30 p.m., Jaclyn, Satiya, Vasu and I were in the DPRS control room to summarize the steps of operating the touch panel to display the parameters to be recorded. We had prepared a written procedure and checklist so the operators could follow up easily.

Between 10.00 a.m. and 5.15 p.m., Jaclyn, the operators and I were in WWTP to follow up on the new DAF commissioning. Istiak, a process engineer, was in charge of the new DAF commissioning project. The old, small DAF unit was switched off while the influent was fed into the new, larger DAF unit. The mechanical parts such as the scrapper system of DAF were in normal operation.

Istiak performed a simple jar test experiment to monitor the chemical dosing systems of the flocculator at the site. The chemicals used for DAF are FeCl₃, NaOH and polymer solution. The desired outcome is a distinct separation between floc sediments and a relatively clear solution. The chemical dosing systems are ready for operation except for NaOH.

At the same time, three intermediate bulk containers (IBC) of NaOH arrived for DAF commissioning. The NaOH dosing pump was tripped several times after turning on. Istiak suspected that there was an airlock in the pipeline connecting the IBC and NaOH dosing point on the flocculator. However, the contractors were taking half-day leave and we had tried several alternative methods so that NaOH could be effectively dosed to the DAF system. It took a certain time to fix this problem.

Later we adjusted and monitored the chemical dosing systems for several times by trial and error. Eventually, we obtained a satisfactory outcome before sending it into the DAF separator unit.