RAS & WAS Pumps (FLYGT Pump)

Transcription

1 RAS/WAS Pumping Pumping of sludge from the secondary clarifiers to the aeration tanks maintains active biomass in the aeration tanks This is referred to as return activated sludge (RAS) pumping RAS pumps are proposed, each sized at approximately blaa blaaa This arrangement will allow for one duty pump and one standby pump per tank The RAS pumps will be located in the basement gallery between the new aeration and secondary clarifier tanks RAS pumping has been sized for a flow rate of 100% of the average influent flow to the plant It may be possible to consider reducing the number of standby pumps through common standbys, which should be further evaluated during preliminary design A portion of sludge from the secondary clarifiers will be wasted on a regular basis The waste cycle can be automated for a certain time period or volume on a timed basis (for example, 10 minutes of every hour), or can be performed according to operator preference This is referred to as waste activated sludge (WAS) Proposed WAS pumps, each sized at approximately blaa blaaa WAS flow rates are based on the minimum discharge line size of 4 and a velocity of 1 m/s to accommodate pumping of solids, therefore, the pumps would have a flow rate in the range of blaa blaam3/day Each tank will have a duty pump, with cross connection so that the standby pump can waste sludge from any clarifier should one duty pump be out of service The WAS pumps will be located in the basement gallery between the new aeration and secondary clarifier tanks It is sometimes suggested that WAS pumps can be eliminated by allowing sludge wasting off of the RAS lines This is not a recommended practice due to the significant difference in hydraulic head conditions between the RAS and WAS lines, and the requirement for pinch valves for control of flow This has been practiced at other plants, with limited success, and the

2 pinch valve often requires significant maintenance Dedicated WAS pumps are recommended RAS & WAS Pumps (FLYGT Pump) Secondary sludge pumping (RAS/WAS) is a part of the treatment plant process Return activated sludge (RAS) is continuously pumped back into the secondary biological treatment tank as part of the treatment process Excess from the settled sludge, which is waste activated sludge (WAS), is pumped to the sludge handling process Related applications include pumping sludge from septic tanks, industries and other wastewater treatment plants into the process Channel impeller pumps These submersible Flygt C-pumps are built to handle capacities of up to 3000l/s (48000 gpm) with motors up to 775 kw (1050 hp) The standard versions of these pumps are made in cast iron and also come in industrial configurations for more

3 demanding applications like municipal sewage and industrial effluent Explosion-proof versions are also available The classic C-pumps with shrouded single and multivane impellers have proven themselves over the years They are designed with an extensive range of hydraulic units available to handle different types of media These submersible pumps require neither special housing nor a superstructure to support them, thereby reducing construction costs considerably They are also designed to be small with motor and hydraulics integrated into one compact unit, which means that pumping stations are smaller and less complex to build The smaller C-pumps come with the Flygt Nevaclog impeller, which has excellent flow-passing properties The multivane impellers for bigger pumps are designed for optimum hydraulic efficiency Operating submerged, the pumps take up less space, and noise and cooling problems are virtually eliminated N-technology pumps Flygt N-pumps handle capacities of up to 1,000 l/s (16000 gpm) with motors from 13 to 310 kw (15 to 415 hp) and pumping heads of up to 100 m (330 ft) These self-cleaning pumps feature innovative features and functions that make them the most intelligent choice for a broad range of applications The hardened cast iron version is ideal for typical wastewater applications and the chopper ring version is perfect for cutting long fibers or solids The Hard-Iron version should

4 be used in abrasive applications and waters where the cold causes erosion corrosion due to high oxygen content Mixed flow pumps, submersible These mixed flow pumps are designed to be the most costeffective medium head pumps with capacities of up to 5,000l/s (80,000 gpm) Typical applications are water supply intakes, effluent pumping in treatment plants, and water attractions These mixed flow pumps are high-capacity, medium-head pumps for clean and screened contaminated water Flygt submersible mixed flow pumps operate directly in the pumped liquid and are easily installed and removed The breadth of the product range makes them the ideal choice for a number of applications and for meeting specific performance requirements The submersible mixed flow pump can be installed in many different ways to ensure cost-effective pump solution with high quality products and low overall costs

5 Propeller pumps, submersible Flygt propeller pumps are modern and are designed to be the most cost-effective high-flow pump range with capacities of up to 5,000l/s (80,000 gpm) Typical applications are storm water, waste water, water attractions, plant water intakes, and effluent pumping in sewage treatment plants Flygt propeller pumps are state-of-the-art high-capacity, lowhead pumps for contaminated and clean water Flygt submersible propeller pumps operate directly in the pumped liquid and are easily installed and removed The breadth of the product range makes them the ideal choice for a number of applications and for meeting specific performance requirements The pump s small footprint and the resulting compact pump station makes for very cost-efficient pump stations The submersible propeller pump can be installed in many different ways to ensure a cost-effective pump solution with high quality products and low overall costs Ultra-low head pumps, submersible

6 Flygt ultra-low-head pumps are modern and designed to be costeffective high-flow pumps with capacities of up to 1,300l/s, (21,000 gpm) Typical applications include return activated sludge in WWTP s, water attractions, irrigation canals, and aquaculture Flygt ultra-low-head propeller pumps are state-of-the-art high-capacity ultra-low-head pumps for clean and lightly contaminated water These submersible pumps are horizontally installed and operate directly in the pumped liquid, they are very easy to install and remove The product offering makes them the ideal choice for a number of very-low-head applications The pump s compact size and the resulting compact station make for a very-cost efficient pump solution The typical pump is installed directly on a vertical concrete wall with the discharge line going through the wall for the lowest installed cost Pump supervision

7 We provide pump monitoring systems well adapted for the different models of pumps and mixers Monitoring systems such as Flygt MAS are designed to protect and stop a pump when necessary They emit alarms, record measurements from sensors and modules, and have a powerful troubleshooting function The embedded web functionality enables Internet access Pump and process controllers Our wide range of pump and process controllers is designed for use with a variety of pumping applications Each controller comes with a reliable alarm system and well thought out functions such as comprehensive pump control, advanced supervision of pump conditions, accurate flow calculation and an open communication platform SCADA

8 The Flygt AquaView SCADA software provides a complete overview of entire water and wastewater systems It transmits alarms in the case of failures, logs data for reports, trends and events, and continuously monitors the state of linked pumps, mixers and valves The data, ie pumped volume, inflow, water level and different kind of pump statistics, is clearly viewed and easily accessible In wastewater treatment handling, pump breakdowns could cause severe environmental impact With the foreseeing alarm distribution, such problems can be predicted and avoided Flygt AquaView can be viewed in real time with a PC from virtually anywhere, and it can communicate with different protocols Pump drives Intelligent pump drives are designed for driving wastewater pumps Features include smart flow, level control, cleaning

9 function, sensor-free pump protection, and multi-variable control Flygt PS 200 for example derates the pump, regulates the speed and helps it run efficiently Summary of Process Tankage and Equipment Treatment Unit Number of Units SCREENING No of Screens No of Screening Washer/Compactors 2 (duty/standby mechanical) 1 GRIT REMOVAL No of Grit Tanks 2 (1 duty, 1 standby) Volume of tanks (m3) total Volume per tank (m3) Dimensions per tank Length (m) Width (m) Depth (m) liquid PRIMARY CLARIFICATION No of tanks Primary clarification area (m2) total

10 Treatment Unit Number of Units Primary clarification area (m2) per tank Dimensions (each tank) Length (m) Width (m) Depth (m) AERATION No of Aeration Tanks Total Aeration Tank volume (m3) Volume per Aeration Tank (m3) Dimensions (each tank) Length (m) Width (m) Depth (m) Aeration Blowers Process Air (per tank) (3 duty, 1 standby), Variable Frequency Drives average daily flow peak flow FINAL CLARIFICATION No of final tanks Final clarification area (m2) total Final clarification area (m2) per tank Dimensions (each tank) Length (m)

11 Treatment Unit Number of Units Width (m) Depth (m) Scum Pumps (one duty per tank) RETURN AND WASTE SLUDGE PUMPING RAS Pumps RAS Pumping Rate WAS Pumps WAS Pumping Rate (1 duty, 1 standby per aeration/secondary tank) 100% of Average Day Flow returned to aeration tanks Approximately 11 kw (14 HP) (1 duty per tank, 1 common standby) Governed by minimum pipe size of 4 and velocity of 1 m/s therefore pumping in the range of 650 m3/d typically operated from 3-15 minute per hours BIOSOLIDS TREATMENT Type of Digester No of Digesters Anaerobic Both operated as primary Digester volume (m3) total

12 Treatment Unit Number of Units Digester volume (m3) per tank WAS Holding Tank Digested Sludge Holding Tank SLUDGE DEWATERING Type of Equipment No of Units (Duty/standby) Capacity (m3/d) per centrifuge Centrate Holding Tank 103 kg/d at feed solids concentration of 27% (operated 5 days/week, 7 hours/day) Conventional Activated Sludge Conventional activated sludge for secondary treatment generally consists of an aeration and secondary settling tank system (final clarifiers) The aeration tanks provide an environment for biomass to grow which in turn remove pollutants in the wastewater through their biological processes The biomass is easier to settle out of the wastewater as it increases in size through digestion of the pollutants, and is removed in the final clarifiers A portion of the solids removed is recycled to the aeration tanks to maintain a healthy biomass population, and a further portion is wasted daily and further processed through digestion and

13 solids handling facilities for disposal Screening Grit Removal Primary Clarification Aeration Final Clarification Disinfection Digestion Dewatering