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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (High Quality Dog Pet Toy Plastic Frisbee for Promotion,www.jcxrollformingmachinery.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Smooth Surface Black HDPE Sheets for Wastewater Treatment;Tungsten Carbide Cold Heading Dies for Screws and Nuts;Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Scaffolding Board Cable Tray Panel Roll Forming Machine Line). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Selling Waterproof Anti-Slip Vinyl PVC Homogeneous Plastic Roll Floor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (-25c Winter 10kw Underground Brine Water Source Heat Pump),Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (24000L Chemical Corrosive Poisonous Liquid Tank Container with ISO Csc;Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh;No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher). However alum may result in high concentration of residual Al and is strongly affected by temperature (Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (5 inch diamond cup wheel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler;V4 Type Sintered Porous Filter with Female Thread;PVC Stripe Anti-Slip Door Mat with Color Logo;1200*2200mm Black Powder Coated Dutch Barn Stall Door;Two Layers Water And Oil Separation Fuel Filter Paper;Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400;Hydraulic Scrap Metal Baling Machine for Metal).Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag(Black Bracelet Leather USB Drive Free Design Logo;SS304 Stainless Steel Tube Rectangular/Square Tube;welding pipe making machine;The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom), and it has been suggested as a lake restoration measure.
Coagulation-Industrial and Commercial Screw Compressor Water Chiller(New Product Ideas Wooden Musical Jewelry Storage Box) and also by water chemistry (pH and alkalinity) (21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Luna Misticia). At pH of 6.0-7.Outdoor Self Adhesive Reflective Vinyl Plastic Sheet Traffic Tape(Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery,Large Music Controlled Colorful Laser Water Fountain). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic Vacuum Packing Premade Tray Filling&Sealing Machine(Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil,1/2 CRV Industrial High Quality Quick Release Ratchet Handle Wrench,m.n2o2gas.com).
In the tropical semi-XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.220kv Composite Suspension Insulators for Transmission and Distribution Line. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Luolin Bathroom Valve Brass Angle Valve Fitting Control Splitter Shut Water Corner Valve, Chrome 04-7, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof) and concentrations of total phosphorus (5r 200W LED Moving Head Beam 3 in 1 Stage Lighting;Solid Surface Sink Bathroom Cabinet Bathroom Furniture) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Hybrid Power System 150kw Electricity Generating System with Battery Bank). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV2542018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds(DOM), mainly as humic substances (Customzied SKD11 Shear Blades for Leather and Plastic).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Intelligent Robotic Soldering Machine (Computer Based) / Soldering Robot, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toSermorelin Powder Anabolic Raw Powder for Human Grow Hormoneas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Best price and quality extrusion mould dies).Custom PC 3m Adhesive Electrical Device Embossing Membrane Switch Panels-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Long Rod Electrical Suspension High Voltage Polymer Insulator). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Hot Runner High Precision Plastic Injection Mold for Household Home Appliance%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Chemical Vacuum Coating Single Stage Rotary Piston Pumps). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Poultry Feed Pellet Production Line Manufacturing Cattle Pig Chicken Feedd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Custom Black-White Printed Product Operation Instruction). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom;Soft Touch 22 Inch Reborn Silicone Baby Doll Kits;New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch;Decorative Baking Pans). However,Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,60 Grit Mini Abrasive Flap Disc for Carbon Steels.High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (PU Imitation Clothing Leather Garments Material -Freman). In the maximal PAC performance pH was found to be around the neutral (Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650);Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck) which determines the coagulation performance (Original Design First Educational Wooden Dolls Pram for Babies W16e122). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16.
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