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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 (Alternator for Toyota 91,Caterpillar Komatsu Hitachi Jcb Excavator Slewing Bearing Spare Parts). As a result, several chemical methods have been applied to control P internal loading worldwide (Guard Rail Roll Forming Machine 2.0-4.0mm Thickness;China Genuine Leather White Color Safety Shoes;HS20-600 Shipping Lifting Device Customized Hydraulic Station). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (China Supplier Customized Polish Storage Wall Mounted Wine Rack). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Non-Woven Bag Making Machine for Handle Bag (ZXL-C700)),Genuine 1m USB Date Charging Cable for iPhone. 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 (Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use;Zp9 Punches and Dies Rotary Tablet Press for USA Market;Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ce Marked Nylon Disposable Cleaning Brush for Endoscope Channel) 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 (Metal Crafts 6 Bottle Wine Bottle Holder Metal Wire Wine Rack). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863;Gi Galvanized Iron Sheet Hot Dipped Galvanized Steel Sheet Galvanized Sheet Metal Plates;Commercial Promotion White Inflatable Party Tent for Exhibition;Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car;cnmirant;Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag;Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor).12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch(Frontlit PVC Flex Banner for Outdoor Advertising;Cc+ Hot Sale Atc Spindle with Gmn Bearing Air Cooling Spindle Same as Italy Hsd;Lab Work Bench for Hospital Disease Control and Prevention System;60 Ton Track Material Handling Excavator for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Industrial Aluminum Extrusion Profiles 6063 T5), and it has been suggested as a lake restoration measure.
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In the tropical semi-Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover-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.Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands. 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
Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap, 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(LED Display Fixed Co Gas Monitor Toxic Gases Analyzing) and concentrations of total phosphorus (Rare Earth Metal Material Cerium Target for Magnetron Sputtering System;New Crystal Perfume Bottle Glass Bottle Empty Bottle Spray Perfume Bottle Large Capacity 25ml) 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 (Composite Suspension Transmission Insulator String with Electrical Power Fitting). 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). UV254High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System(DOM), mainly as humic substances (SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker).
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.)Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale, 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 to12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storageas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Brown Color Oil Seal).Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)-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 ( Solar Water Pump for Garden Irrigation (SC Series)). 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 UV254Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Smart Label RFID UHF Sticker with Special Offer for Asset Tracking). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Electric Cartridge Heating Element for Prototype Printing Machined).
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(2019 Hot Sale Solar Light String Tree Park Decoration Light). 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 (New Style Customized Ce Approved Adjustable Inline Skate (SS-179A-BW)). 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,Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking, 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 (Digital Universal High Power Ku Band Single LNB Price;High Quality Centrifugal Industrial Push-Pull Ventilation Husbandary Exhaust Fan;Wholesale Factory Price Cheap Arctic Cat ATV Parts Custom Size 4X4 ATV Tail Lights;Gold Star Square Glass Candle Holder for Wedding Decoration). However,Factory Direct Sale Baseball Uniform for Adults.
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,130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W.Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board, 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 (Q235 Galvanized Steel Hoop Iron Strap for Packaged Timber House). In the maximal PAC performance pH was found to be around the neutral (8PCS*10W RGBW LED Spider Moving Head Beam Stage Light;Best Custom Private Label Glass Pillar Paraffin Votive Birthday Flameless Scented Candle with Jar). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Surge Protector Lightning Arrester Lightning Arrester) which determines the coagulation performance (Metal Chair Dining Set). 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 (Multi Function Baby Bbags Maternity Diaper Backpack for Mom).
13.56MHz Logo Printing Mini NFC Epoxy Card for Access System, charge and density, factors that influence directly in flock sedimentation.Automatic Monochrome Crystal Shoe Injection Molding Machine(Paper Making Machine Sand Filter Ceramic Nozzle;Caprolactam Grade Ammonium Sulphate (21%Min)). 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 (Fu Style Alloy Steel Conveyor Chain with High Quality). Extracellular and surface-Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer(Products,T30 CNC Turret Punching Machine Sheet Metal Fabrication Price for Sale). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Cheap Plastic Injection Molding/Plastics Mold Making Cheap Price), which can be one important cause of the increase in coagulant demand in algae-rich waters (12V 24V DC Brushless Centrifugal Circulation Pump).Thermoplastic TPE Granules Making Machine for Grass Filling(Patio Outdoor Home Hotel Office Restaurant Aluminum Polywood Dining Table and Chair), particularly humic susbtances. Humic substances are highly negatively charged (Chemical Powder Hydroxypropyl Cellulose HPMC for Gypsum Plaster), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine). Maximal UV254removal was observed to be found around pH 6.0 (Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997)). 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 (3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck.
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