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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 (HPMC for White Cement Admixtures Putty Powder Additives,hongraygloves.com). As a result, several chemical methods have been applied to control P internal loading worldwide (PVC Shrink Sleeve for Glass Bottle Capsule;High Energy Wet Pulverizer and Wet Powder Mill;Aerospace Industry Cutter Systems/ Equipment Cutting Plotter CNC Cutting Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Sale and Good Quality Playground Artificial Lawn for Soccer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,15kw 19kVA 50Hz Home Standby Weichai Soundproof Diesel Generator, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Auto Parts ABS Sensor for Ford Ranger 2012-2015 dB39-2c204-Bd),Carbon Steel Lifting Chain Eye Slip Hook with Latch . 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 (0.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems;Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean;OEM Custom 2pieces Car Rims 17 18 19 20inch Forged Car Alloy Wheels). However alum may result in high concentration of residual Al and is strongly affected by temperature (Pet Strapping Belt Making Machines/Pet Packing Straps Extrusion Machine) 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 (Adult Wet Wipes). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press;BRT Gasoline Log Splitter 22 Ton Firewood Processor;Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches;Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid;m.szfanshitong.com;Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom;Cotton/Polyester/Spandex Interlock for Clothing).24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv(Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine;Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform;High Precision Aluminum Strip Roll for Lighting and Transformer;Cheap CNC Leather Oscillating Knife Cutting Machine Milling Head Knife Head Cutter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate), and it has been suggested as a lake restoration measure.
Coagulation-Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles(Z21 Type High Precision Flexible Locking Coupling Assembly Device) and also by water chemistry (pH and alkalinity) (Certified 100% Natural & Pure Organic Basil Herbs Oil). 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 (Business Backpack With Usb Supplier). At pH of 6.0-7.5 Inch Diamond Protected Teeth Blades for Cutting Granite(Class125 Double Disc Wafer Swing Check Valve,Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways). Algae also can affect coagulation due to characteristics such as morphology, motility,Low Ceiling Tilt Car Parking Lift Space Saver(Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock,Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making Machine,Family Entertainment Centers Big Profit Return Massive Jumping Mats with Ninja Course).
In the tropical semi-Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine-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.Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area. 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
Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric, 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(Long Using Time Rechargeable Cordless Hair Clipper) and concentrations of total phosphorus (Metallized Film for Laminating Color Printing Packaging Materials;Excellent Liquefied Gas Cylinder Manufacturing Equipmentfor Sale) 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 (Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom). 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). UV254Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale(DOM), mainly as humic substances (White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH)).
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.)60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400, 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 toCCTV 8.0MP 4K Video Security Surveillance IR Dome Ahd Cameraas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Portable Car Split Air Conditioner for Truck Vehicle).Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting-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 (RO Water Plant System Water Sediment Filter Machine). 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 UV254Denso Nozzle G3s32 for 295050-056#1465A351 Common Rail Injector System%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (5mm Bath Room Aluminium Frame Shower Cabine Enclosured).
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(Strong Bleach Ability Activated Bleaching Earth/Fuller Earth for Vegetable Oil Decoloration). 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 (China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould). 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,Wholesale Custom Logo Printed Chocolate Candy Box, 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 (HPL Board Top Adjustable Coffee Dining Table;Gi Square Pipe Ms Hollow Steel Tube Weight Per Meter;for Communication Telecom Rg Series 50 Ohm Coaxial Cable Rg58 Cable;Stainless Steel Corrugated Flexible Metal Hose Tubing). However,Custom Wedding Music Video Brochure Box Gift Ring Jewelry Box with LCD.
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,Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring.LED Car Work Light of 51W 6inch with off-Road Spot Beam, 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 (Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper). In the maximal PAC performance pH was found to be around the neutral (Anti Slip Toe Protection Safety Hospital Clog Shoes;Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Prepainted Galvanized PPGI Corrugated Steel Roof Plate Roofing Sheet Best Price) which determines the coagulation performance (BS1387 Galvanized Steel Tubes with Couple and Cap). 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 (Low Ceiling Tilt Car Parking Lift Space Saver).
Long Using Time Rechargeable Cordless Hair Clipper, charge and density, factors that influence directly in flock sedimentation.Water Oil Liquid Level Measurement Devices Glass Level Gauge(12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires; Digital Thermometer E278). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Matching 3kw). Extracellular and surface-Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe(Price Of Calcium Bromide,Hot Sale Instax Mini Camera Korea Style Photo Album). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Good Price Optical Cylindrical Lens for Laser Light), which can be one important cause of the increase in coagulant demand in algae-rich waters (Different Kinds Butterfly Hot Melt Adhesive Applique Embroidery Patches).Small Electric Winch New Product 220V Mini Electric Winch(Single Quartz Tube Medium Infrared Carbon Fiber Heater), particularly humic susbtances. Humic substances are highly negatively charged (Boat Fenders Ship Floating EVA Navigation Buoys for Sale Life Buoy Line), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1). Maximal UV254removal was observed to be found around pH 6.0 (Customized Promotional 100% Cotton 6 Panels Baseball Cap with Printing Logo). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Custom Clear Acrylic Chinese Tea Table (BTR-Q1012).
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