Banyu Urip reservoir management heavily rely on river-sourced water as water injection to meet Voidage Replacement Ratio target of 1. The treatment facility which consist of Raw Water Basin, Clarifiers, Multi Media Fine (MMF) Filters and Cartridge Filters, is sensitive to seasonal transition and river condition. This paper shares lesson learnt in operating such facility and troubleshooting guidance to overcome challenges of high turbidity during rainy season and lack of river water volume during drought season.

To maintain the design intent of Banyu Urip (BU) water treatment facility in achieving water injection quality and quantity at reasonable cost, following activities were undertaken: [1] Critical water parameters data gathering & analysis across each unit; [2] Clarifier Chemical injection dosage verification based on laboratory test; [3] MMF Media coring inspection to assess the filtering media condition; [4] MMF Filters backwash parameters optimization; [5] MMF Filter on-off valve sequencing optimization to address water hammering issue; [6] Water injection rate management to deal with river water source availability along the year.

Critical water parameters analysis revealed that chemical dosages were in-adequate to treat the five times higher turbidity coming into Clarifiers during early rain 2019. On top of this, low Raw Water Basin level at the end of long drought further contributed to jeopardize Clarifier's operation. Although in-adequate chemicals injection was resolved at early 2020, the treatment cost remained high, especially on filtration section. Media coring result on MMF Filters confirmed that the filtering media have been poisoned by carried-over mud from Clarifiers during upset. The operation of MMF Filters required extensive optimization on backwash parameters to successfully recover the MMF Filters performance without media replacement. Latest media coring on the worst MMF Filter showed that there was no more top mud layer and the amount of trapped mud had been decreased significantly. Cartridge Filter replacement interval was improved from 38 hours to 186 hours, therefore water treatment cost dropped with quite significant margin. Additionally, the availability of each MMF Filters was also improved. At the same time, the high water injection rate during 2020 rainy season, had successfully increased reservoir pressure buffer up to its maximum point as the anticipation of prolonged drought season.

This paper provides the troubleshooting guidance for MMF Filter application in season-prone water treatment facility including insights on interpretation of media coring result and linking it back to optimization strategy on the MMF Filters drain down time for effective backwash process without having excessive media loss.

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