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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 (Compatible Physio Control 11996-000033 NIBP Hose,0.80mm Female Header SMT Type with Post PCB Connector). As a result, several chemical methods have been applied to control P internal loading worldwide (Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly;Custom PVC Shrink Capsules for Liquid Bottle;Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Three-Phase Electronic Multi-Function Watt-Hour Current Meter). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot New Products Electric Wheel Loader Dumping Dumper, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Baby Rubber Rain Boots Suppliers for Sale),Working Safety Glove with Latex Coating for Guangzhou Sample. 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 (Valve Wheel Adjustable Hydraulic Impact Torque Wrench;Fashion Double Striped Non-Slip Entrance Mat;Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow). However alum may result in high concentration of residual Al and is strongly affected by temperature (DC Colorful Battery Operated Small Hand Fan for Outdoor Use) 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 (Hydraulic Patch Closer For Glass Door). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve;TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use;Wholesale Comfortable Men′s Winter Leather Snow Boots;Promotion Cheap Woven Wristbands Event RFID Woven Wristband;Custom Paper Hang Tag with Metal Eyelet for Garment;Non Woven Wheel for Stainless Steel Polishing and Grinding;High Quality Free Sample Woven Label for Garment Accessories).Cylinder Actuated Cement Powder Butterfly Valve(Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Shenzhen Customized Metal Stamping Parts Fabrication Service;Construction Used Power Wheelbarrow for Sale;Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155)), and it has been suggested as a lake restoration measure.
Coagulation-Micro Water Tank Level Transducer for Wall Hung Gas Boiler(Micron Circular Stainless Steel Filter Disc) and also by water chemistry (pH and alkalinity) (PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble). 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 (Addressable Sounder Circuit Module). At pH of 6.0-7.Economical Small Bench Metal Mini CNC Lathe (CK6130 CK6132)(China New Technology Swimming Pool Heat Pump (MDY50D),Agriculture Machinery Belt Banded Cogged V-Belt). Algae also can affect coagulation due to characteristics such as morphology, motility,250ml Empty Refillable Pet Material Plastic Shampoo Bottle(Nonwoven PP Fabric Nonwoven Needle Punched Geotextile,12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape,2018 Compression Football Socks/Knee High Lycra Socks/Compression Soccer Socks).
In the tropical semi-High Speed Automatic Cleaning Scourer Making Machine Manufacturer-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.Magnetic Badge Holder Rectangle Magnet Button Badge Maker. 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
Multi-Viewing Biological Microscope with Good Price, 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(600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth) and concentrations of total phosphorus (High Quality Galvanized Pan Head Self Drilling Screw;Samsung Tv Screen Repair Led) 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 (Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw). 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). UV2540.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens(DOM), mainly as humic substances (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes).
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.)1212 1218 1224 1313 CNC Router 4 Axis/Automatic 3D Wood Carver Machine with DSP Controller, 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 toJumbo Drilling Rig with Three Arms (HFG-33J)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Galvanized C Purlin).European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle-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 (Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer). 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 UV254Compatible Quality Handy Color Jumbo Stretch Cling Film%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Miniature Round Boat Spst Lighted Rocker Switch 120Vd).
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(Siboasi Best Selling Badminton Shuttlecock Feeder Machine). 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 (ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts). 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,Cow Horse Trailer Ramp Stall Stable Rubber Mat, 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 (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine; Welding Parts;PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer;Dia. 17mm-130mm High Chrome Casting Grinding Mill Ball Manufacturer in China). However,Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe.
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,Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve.Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack, 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 (High-Class Sld-6121 Paper Sticker High Speed Slitting Machine). In the maximal PAC performance pH was found to be around the neutral (Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer;Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)) which determines the coagulation performance (g2 - Yoga Hammock Swing). 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 (China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China).
Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E), charge and density, factors that influence directly in flock sedimentation.Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence(Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit;LG936 LG938 Front End Loader Parts Gas Spring 29330011391). 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 (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump). Extracellular and surface-2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink(Type C to Audio and charging adapter for mobile phone,360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Plastic Casement Window), which can be one important cause of the increase in coagulant demand in algae-rich waters (Good Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet).20qt Portable Small Rotomolded Insulated Medical Cooler Box(Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D), particularly humic susbtances. Humic substances are highly negatively charged (High Quality Heat Resistant Teflon Adhesiev Tape), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring). Maximal UV254removal was observed to be found around pH 6.0 ( IPS 720*1520 Display Android 9.0). 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 (Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale.
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