Soneva Gili Resort Comments on existing STP 27. August 2008
3 Current sewage system Soneva Gili STP designed for 80m³, actual load 160m³ Septic tank 80m³ Standard Overflow Desalinated water tank 245m³ Sewage treated water tank 164m³ Rotating disc Sludge separation Chlorine dosage Buffer tank Overflow RO Waste water Fresh water Smell, no clear water, black tank, bio activity?
4 Septic tank
5 Rotating disc, sludge separation, chlorine dosage
6 Chlorine dosage with small buffer tank
7 Sewage treated water tank
8 Water consumption Soneva Gili July June 2006 July June 2007 Consumption - liters
9 Water Consumption Soneva Gili Data from July to April are from Data May and June from 2006
Improve STP at Soneva Gili Challenge: - Higher daily volumes then anticipated - Higher load (incl. laundry) then anticipated - No waste water relevant data available - Mixed responses on “smelly” waste water used during irrigation Options 1. Do nothing 2. Improve current operation 3. Add another rotating disc to cover ‘Increased volume’ 4. Add another section to improve ‘effluent quality’ on top of option 3 5. Replace with new STP 10
Option 1 : Do nothing Even if there are no guests or hosts complaints and legal effluent standards are met we would still recommend Option2: Improve current operation 11
Option 2 : Improve current operation 1. Water analysis (Quality) Existing sewage at different measurement location: After the laundry Before the entry into the septic tank (laundry and other sewage combined) After the septic tank and before the entry into the rotating discs (after first treatment) After the rotating discs and before the chlorination Important measurements are COD, BOD, Suspended solids, NH4-N, any other parameters offered by the supplier Frequency: Every two weeks for a period of 8 weeks 2. Water analysis (Quantity) Water meter to be installed at the entry into the septic tank system to measure peak flows and average flows. Daily and hourly readings These data will be used a standard effluent parameters for any Six Senses resort assuming similar loads and volume fluctuation. Important: Commenting on effluent quality from laundry and its impact on STP operation 12
1. Check and repair grease trap 2. Increase cleaning frequency of pre treatment step. Sludge level should not be higher then 30cm below the deepest water level of pretreatment. Floating sludge should not be thicker then 10cm otherwise it should be destroyed manually 3. Regular cleaning of biological growth that connect the discs 4. Regular cleaning lamella separators and extract any floating sludge 5. Control of treated water tank for sedimentation that increase fouling potential 6. Check dosing of chlorine and ensure that 0.5mg/l is still left in the treated water tank 7. Increase of pretreatment volume if possible 8. Install simple sand filter after last treatment step and before chlorination 9. Check if black tank attract heat that transmits into stored water. Protect black painted from direct sunshine, if possible paint it white to reduce heat transfer to store water as cool as possible. 10. Most important: Get real data on flow and contamination level as indicated not only for Soneva Gili but as benchmark for all other Six Senses resorts 13 Option 2 : Improve current operation
Option 3+4: Extension of existing STP plant – Not recommended 14 Increase volume € 40,000* Increase effluent quality € 130,000* *See detailed quotation from S+P
Option 5 : Replace with new STP This option is only recommended if - Option 2 does not improve situation - The proposed SBR for Soneva Fushi is successfully implemented - Sufficient STP relevant data has been collected - Budget allows (estimated costs: SBR based on Soneva Fushi Design ca. € 75,000) 15