Water and Energy - Draft Report of the GWRC Research ... - IWA

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In comparison with the control, the five-month field study showed that the ultrasound pretreatment of the sludge resulted in an increase in the daily biogas production up to 35%. There were no significant differences in compositions of the biogas from the two digesters. When translating the increases in the biogas production into its source – volatile suspended solids, a 25-30% increase in sludge solids removal is expected under optimal hydraulic retention time. Application of Anaerobic Selector at Jurong WRP and Kim Chuan WRP – completed Jurong and Kim Chuan WRP currently uses conventional aerobic process for treatment of wastewater. The anaerobic selector process can be incorporated into the aeration tanks by creating an anaerobic zone in the first pocket of the aeration tank. An anaerobic selector process has been documented to favour the growth of floc forming bacteria and improve sludge settleability. It is also known to be effective in removing phosphates and COD from the wastewater. A significant portion of (Soluble Chemical Oxygen Demand) SCOD in the settled sewage (including Acetic Acid) was removed concomitantly with PO4 3— P release in the anaerobic selector. SCOD removal under anaerobic conditioned is verified so savings in aeration energy is possible. The projected reduced in aeration energy of 8% (21 kW) is translated into annual savings of S$20,000 Memstill – completed TNO developed within a Dutch consortium that includes Keppel Seghers Netherland, a membrane-based distillation concept in which multi-stage flash and multi-effect distillation modes are combined into one membrane module. This so-called “Memstill ® technology” is expected to improve the economy and ecology of the existing desalination technology for seawater and brackish water favourably. This is especially ascribed to the fact that a Memstill ® module houses a continuum of evaporation stages in an almost ideal counter-current flow process which makes a high recovery of evaporation heat possible. The energy requirement for Memstill ® technology can be fulfilled with low-grade thermal energy such as waste heat or renewable energy (e.g. solar energy), which makes Memstill an environmentally friendly process. In collaboration with both National Environment Agency (NEA) and Public Utilities Board (PUB), Keppel Seghers Engineering Singapore carried out testing for more than a year in Singapore on a pilot plant with an initially estimated capacity of 1 – 2 m 3 /hr. The testing results is shown in the table below: Parameters Memsing E-On Next Pilot Plant Targeted Flux (L/hr/m2) 0.25 2.5 5 Energy efficiency Reasonable to assume even (%) 30 50 better performance judging from 80 Heat input (MJ/m3) 1000 - 2000 400 improvement made from previous 2 pilot plants 240 Future Memstill modules with improved designs are expected to achieve even higher energy efficiency and less heat input. Thicker spacers are used to allow higher feed flow rate. A different type of membrane condensers are adopted to provide more efficient heat transfer. A third Memstill pilot has been manufactured to include these improvements and will be tested in GWRC Water & Energy - Draft report 54
AVR, Netherlands. The AVR pilot is expected to further link up the gap towards targeted performance parameters. Keppel Seghers intends to build a second Memstill pilot plant in Singapore to further its understanding and experience with Memstill technology and hopefully to demonstrated an improved performance. Ongoing projects Membrane Bioreactor (Demo Plant) – in progress Baseline performance is being established. The plant has been in operation since Dec 06 and have stable operations at membrane flux of 25L/m2-h and energy consumption between 0.5 - 0.6 kWh/m3. This is lower by 0.3 kWh/m3 compare to the normal operation of MBR. The 0.55 kWh/m3 includes the energy required by: • Drum screen • Blower for membrane • Blower for aerobic tank • Pump for sludge supply from aerobic tank to membrane tank • Pump for sludge circulation from aerobic tank to anoxic tank • Pump for membrane filtration • Permeate pump which pumps the MBR permeate to the product tank which is approx. 400 meter from the MBR plant. • Valves • Measurement equipment • Energy consumption for the MBR control building (air-con, lightings etc). It does not include: • Raw water pump • Pumping energy usage to the industrial users after the product tank. Desalination Facility Design and Operation for Maximum Energy Efficiency (AwwaRF Project 4038) – in progress On July 2006, PUB has agreed to participate in this project together with Black & Veatch (lead agent). PUB will contribute as a participating utility. The energy usage at PUB desalination plant (SingSpring Desalination Plant) will be assessed and if required, will be visited for an evaluation of energy balance within various treatment processes. Any potential means of improving efficiency specific to the utility will be identified. The results will be used to develop general guidelines for similar facilities in future. The project is currently on going. Sludge Drying using Pulver Dryer – in progress PUB is currently testbedding a Three-Stage PulverDryer system to dry and resize municipal sewage sludge. This material is approximately 20% solids and 80% moisture. It is very sticky and hard to handle. The PulverDryer test unit is designed to mix the raw materials with dried materials at about 50% to 50%. That material is then processed through a three stage PulverDryer System that will reduce to total moisture of the final product between 65 to 75% solids. The drying and resizing of the material within the PulverDryer allows the PUB to rethink traditional methods of disposing the material in a landfill. Proper processing of this material in the PulverDryer also kills pathogens to EPA levels so the final product can be classified as fertilizer or disposed of in a much more inert state in a landfill. This material can also be GWRC Water & Energy - Draft report 55
Page 1 and 2:
Global Water Research Coalition All
Page 3 and 4: Disclaimer This study was jointly f
Page 5 and 6: GWRC Water & Energy - Draft report
Page 7 and 8: 1. Introduction 1.1 Background Over
Page 9 and 10: 2. Knowledge gaps and research need
Page 11 and 12: Climate change - Water patterns - G
Page 13 and 14: 2.3 Project proposals The participa
Page 15 and 16: achieve the above worded objectives
Page 17 and 18: 4 Conclusion and follow up The main
Page 19 and 20: PROJECT DESCRIPTION 1. Project Titl
Page 27 and 28: Project description for the Tools f
Page 33 and 34: PROJECT DESCRIPTION 12. (Toolbox #4
Page 35 and 36: PROJECT DESCRIPTION 14 Project titl
Page 37 and 38: Appendix B Tuesday, 19 February Pro
Page 39 and 40: Annex C. List of participants Name
Page 41 and 42: Annex E. List of identified knowled
Page 43 and 44: 9. Energy recovery, content and man
Page 45 and 46: Annex G. Information on Member and
Page 47 and 48: Identifies and prioritizes research
Page 49 and 50: drafting the protocol as part of th
Page 51 and 52: polluted areas. If it takes place i
Page 53: Organisation: PUB Singapore Contact
Page 57 and 58: (i) The MD membranes only transfer
Page 59 and 60: Organisation: STOWA - Foundation fo
Page 61 and 62: Organisation: UKWIR Contact person:
Page 63 and 64: Organisation: WERF Contact person:
Page 65 and 66: A new project to develop parameters
Page 67 and 68: Organisation: WSAA & CRC WQT Contac
Page 69 and 70: The most significant future energy
Page 71: ^^ includes 78,191 ML of water supp
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