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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 (Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water,150kw Generator Head). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized Speed 110V-220V 60X60X25mm Axial Brushless Cooling AC Ec Powerful Fan;2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer Machine;Home Security PRO Hunter RF Signal Detector Detect Bugging Devices in Your Home). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Frozen Food). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Food Grade Biodegradable Stand up Pouch Kraft Paper Packaging Bag with Zipper, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (1064nm Diode Laser Equipment),Stainless Steel Welded Wire Mesh BBQ Grill Grate/Mesh for Cooking. 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 (Good Quality R134A Refrigerant Copper Tube Fin Heat Exchanger;Customized Plastic Injection Mould Products Industrial Parts Plastic Cross Pipe;High Pressure Rubber Hydraulic Hose Assembly). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Wholesale Hot Sale Microfiber Car Cleaning Towel) 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 (Casement Window Lock Handle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (9-80V Laser Red Zone LED Work Safety Lights for Forklift Truck;Triangle Plastic Checkout Counter Divider Bar with Logo Printed;Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking;Digital Control Gold Powder Coating Machine for Metals;Zjt Bottom Price and Lightweight Color Steel EPS Sandwich Panel;Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion;Custom C3 C5 Ground Miniature Ball Screw 0802).Tp321 Stainless Steel Coil Tube for ASTM A269(Log Debarker Veneer Rotary Peeling Machine;Real-Time GPS Padlock Container Tracker GPS Tracking Car/Truck Fleet Management;Baby Bath Sponge Die Cutter;Outdoor Food Truck Mobile Food Car for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Durable Soft Polishing Wheel for Polishing Wood and Plastic), and it has been suggested as a lake restoration measure.
Coagulation-Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032)(Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe) and also by water chemistry (pH and alkalinity) (Medical Equipment One Step Tp Device Syphilis Rapid Test Kit). 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 (Ritter Sport Nutrition). At pH of 6.0-7.Chinese Manufacturer Quality Magnetic Filter Drawer Separator(Agricultural Machinery Partslinear Bearings Kh3050, 12V- 48V DC). Algae also can affect coagulation due to characteristics such as morphology, motility,2.0mm Pitch Pin Header SMT Type R Sereis Single Row Dual Housing(Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White,Factory Supply Raw MDF / Melamine Faced MDF Plain MDF with Cheap Price,Environment-Friendly Reclaimed Rubber Suppliers for Sale).
In the tropical semi-2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price-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.High Performance RFID NFC Tag UHF Hf Sticker for Tracking Solution. 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
Tamper Evident Walmart Office Depot White out Warning Void Self-Adhesive Security Tape for Bottle, 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(Acupressure Shakti Massage Mat Kit with Pillow and Carry Bag) and concentrations of total phosphorus (24hrs Continously Running BLDC Motor 3kw 3000rpm 48V;How Much To Set Up A Microbrewery Wholesaler Quotes & PriceList) 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 (2019 Mini I9/I9s Tws Stereo Wireless Headphones Blue Tooth Sport Earphone Earbuds). 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). UV254Long Range RFID Access Control Card for Non-Stop Parking(DOM), mainly as humic substances (All-in-One Fool Metal Continuous Casting Machine/Complete CCM with Very Low Investment).
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.)Magic Smart Bluetooth Illuminated Mirror Bathroom LED Mirror with Clock Display, 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 toGirls Unicorn Costume Party Dress Tutu Kids Cute Flower Princess Pageant Carnival Clothesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(2013 New Backyard Galvanized Chain Link Fence).Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)-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 (China Indoor Fly Killer Kitchen Machine LED Fly Trap Manufacturer). 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 UV2546 in 1 H2 O2 Hydra Facial Water Oxygen Dermabrasion Aqua Peel Skin Clean Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Label Printed Black Matte Smell Proof Aluminum Foil Ziplock Zipper Bags). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (7g Fully Fashion Flat Knitting Machine for Sweater (AX-132S)d).
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(Prime Quality Cold Rolled Steel ERW Tube Mill). 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 (5 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe). 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,76mm Garden Hose Fittings Straight Reducing, 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 (Laminated Curtain Wall Glass with Colored PVB Film;High Frequency Induction Heating Brazing Machine (JL-15/25);Hot Sale Copolymer Coated Aluminum Foil Tape for Cable;Custom Minimalist Leather Credit Card Magic Wallet). However,Yuanchen Nonwoven Needle Punched PPS Filter Felt.
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,Gear Box Forged Steel Bw Ends Full Welded Ball Valve.Engineering Plastic Material, Nylon/PA Sheet, 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 (Stainless Steel 1000W Pipe and Sheet Fiber Optic Laser Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (R134A Best Price Copeland Compressor Zp385kce-Twd-522;Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05) which determines the coagulation performance (Black Finish Tapcon Masonry Drill Bits). 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 (Preparation Concrete Vibrator Shaft with Japanese Coupling).
Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging, charge and density, factors that influence directly in flock sedimentation.Heated Lunch Box/ Food Insulation Plastic Box/Heat Preservation Plastic Box(500ml Stainless Steel Insulated Double Wall Vacuum Drinking Bottle (SL-550);Textile Waterproof Motorcycle Trousers for Sale). 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 (Non-Mainstream Leather Retro Bracelet/ All-Match Fashionable Leather Bracelet). Extracellular and surface-Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile(High Quality Cat Tree, 316 Slot Stainless Steel Tube with Glass). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Ce 20 Aluminum Frame City Electric Folding Bike with Lithium Battery), which can be one important cause of the increase in coagulant demand in algae-rich waters (Latest Simple Personalized Designs Circular Rotating Blanks Metal Custom Key Chains).500ml Amber Pharmaceutical Glass Bottle Medicine Bottle Chemical Bottle Pesticide Bottle(Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve), particularly humic susbtances. Humic substances are highly negatively charged (Subwoofer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (FM200 Automatic Fire Suppression System for Electrical Room). Maximal UV254removal was observed to be found around pH 6.0 (Wholesale Resealable Self Standing Washing Detergent Power Liquid Spout Package Bag/Pouches). 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 (China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile.
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