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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 (Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance,Sigle Line Siomay Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot High Quality Self Service Car Wash Equipment;Pedstal Electric Stand Fan 5 Speed Control Air Cooler;Manufacturers Sell Direct Bullet Design Red Hollow Crown Lipstick Tube). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Packing Machine of Cutting Machine on-Line Jc-EPE-Qd1750 Automatic for EPE Foam Sheet/Film),Thermal Transfer Waterproof Tearproof Matt Silver Pet Label. 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 (Fashion Watch Factory Swiss Quartz Women Wrist Branded Watch (WY-001H);Commercial Industrial Fast Food Chicken Electric Gas Pressure Deep Fryer for Mijiagao;20HP Copeland Scroll Compressor Zr250kce-Tw7-522). However alum may result in high concentration of residual Al and is strongly affected by temperature (Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop) 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 (UL cable gland). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Professional Industrial Cr-V Combination Plier for Cutting;Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type);Women Footwear Ballerina Casual Shoes With High Quality;250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps;5% Humidity Range Temperature Humdity Cycling Environmental Control Chambers;3*42mm Armoured NBR Sheathed Round Electric Submersible Oil Pump Power Cable;Fast Dry Sublimation Transfer Paper 100GSM 74inch for Polyester Printing).SMD P4 Outdoor Full Color Rental HD LED Display( Enginerring Machine;Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant;Kids Prince Motor Amusement Rides Fiberglass 12V Electric Motorcycle for Sale;Supermarket Island Freezer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Carbonizing Kiln Furnace for Making Coconut Shell Charcoal), and it has been suggested as a lake restoration measure.
Coagulation-Toroidal Inductor Coils Tlc/1A-221m-00 for Speaker Use., Radio etc Use.(Construction Equipment 1.5 Cube Materials Portable Concrete Mixer) and also by water chemistry (pH and alkalinity) (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated). 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 (SUS304 Stainless Steel Square Weded Mesh for Crafts). At pH of 6.0-7.Smooth Surface Black HDPE Sheets for Wastewater Treatment(High Speed 6 Color PP Woven Bag Printing Machine,Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors). Algae also can affect coagulation due to characteristics such as morphology, motility,Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel(600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag,1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable,www.miracle-leather-bag.com).
In the tropical semi-High Precision Injection Molding Plastic Parts in China (STK-PL-1055)-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.Fan Cooling Oval Design Commercial Cake Display Showcase Fridge. 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
Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable, 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(1.2V 3600mAh 4/3A size rechargeable NiMH Battery) and concentrations of total phosphorus (12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS;Custom Knit Running Compression Tights Leather Black Fitness Pants for Ladies) 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 (Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising). 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). UV254CNC Machine Linear Guide Accordion Bellows Cover(DOM), mainly as humic substances (Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile).
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.)White/Gray Colors U-PVC Water Supply Pipe for Plumbing System, 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 toEgg Tray Manufacturingegg Tray Mouldegg Tray Packing Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Body Camera Manufacturers).Microfiber Towel Quick Dry Towel Set for Beach, Travel, Swim, Pool, Camping, Outdoors and Sports-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 (Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation). 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 UV254Seamless Steel Rolled Ring, Forged Steel Rings for Large Diameter, Manufacturer of Slewing Ring%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China OEM Cast Iron Tractor Farm Clutch Pulley). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Apple Shape Closed Urine Drainage Bag with Universal Hangerd).
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(Wd800 Small/ Mini Microtunnel Boring Machine Pipe Jacking 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 (Aluminum Recovery Fill Tank for C-4 84-96 Chevrolet Corvette). 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,Inconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipe, 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 (Factory Best Price Portable and Oprional Steam Generator Sauna;Replacement LCD Digitizer for Apple iPhone 6plus;Aluminum Tamper Evident Droppers with Insert Dropper for Glass Bottles;Abrasive Blasting Nozzles Boron Carbide Nozzle in Stock for Sandblasting Gun). However,Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic.
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,Customized Disposable BBQ Bamboo Round Stick and Skewers..Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen, 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 (Bearing Accessories Bearing Ball Bearing Rollers). In the maximal PAC performance pH was found to be around the neutral (Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet;Top Quality Precision Floor Industrial 2 Ton Weighing Scale). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Plastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtration) which determines the coagulation performance (Soft Recycled Polyester Mesh Fabric). 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 (Luxury Black Color Shower Door and Shower Enclosure (MB-226)).
Sesame Almond Cashew Nut Peanut Butter Making Processing Machine, charge and density, factors that influence directly in flock sedimentation.Big Engine, Large Output Forestry Application Biomass Wood Chipper(Acrylic Diamond Polishing Machinery & Plastic Edge Finishing Trimming Machinery;Small Playground Plastic Slide Preschool Equipment Toys for Kids). 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 (Solid Carbide Straight Slot Reamer with Inner Cooling Hole). Extracellular and surface-LED Lighted Mirror with Bluetooth Functions(Electronic PCB Assembly of One-Stop Service Factory,2.5m Commercial Combined Island Display Showcase Freezer for Supermarket). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Solid Surface Grade Grinding Alumina Tyihydrate), which can be one important cause of the increase in coagulant demand in algae-rich waters (LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture).Br42 Red Color Mushroom Head Push Button Switches(45 Degree Copper Pipe Joint in Air Conditioner), particularly humic susbtances. Humic substances are highly negatively charged (750 100-200W PMDC Motor for Home Appliance Sweeper), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Transparent Square Glass Fragrance Oil Roll on Deodorant Bottles with Black Lid). Maximal UV254removal was observed to be found around pH 6.0 (High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader). 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 (Hydra Diamond Microdermabrasion Peel Facial Machines).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper.
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