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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 (Stainless Steel Water Filter Housing RO Systems,EEPROM). As a result, several chemical methods have been applied to control P internal loading worldwide ( Mechanical Infant Scale;Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder;China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Video Endoscope with 5.5 Wireless). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ISO Steel Prefabricated Energy Efficient Prefabricated Workshop Sheds),Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition. 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 (Fresh Mung Bean Filling Stand-up Pouch Packing Machine;Factory Flint Lighter Disposable Cheap Chinese Lighter Plastic Lighter;Portable Ultrasound Machine Vacuum Therapy Weight Loss Physiotherapy Equipment). However alum may result in high concentration of residual Al and is strongly affected by temperature (50*50*5mm Galvanized Angle Steel Bead Angle Iron with SGS Certificate China Supplier) 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 (House Dust Cleaning Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (304 316L 321 904L 2205 1.4401 2507 Hot Rolled Stainless Steel Coil; Air Conditioner;Portable Medical Ozone Therapy Unit Zamt-80 on Sale;Wet Dry Diamond Polishing Pad Concrete Polishing Resin Pads;Hair Brush Bristles; stainless steel 316/304;High Precision CNC Turning Milling with Good Price).Manufactured Goods PPGI Coil Corrugated Steel Sheet(Polyester/PP Short Fiber Needle Punched Non Woven Geotextile Fabric;OEM Basketball Sport Longer Elastic Leg Guard Shin Guard;Car Charger With Usb And Cable;High Purity Granulated Sodium Chloride for Deicing Road Salt) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Galvanized Wire Rope Sling with Eyes at Both Ends), and it has been suggested as a lake restoration measure.
Coagulation-Organic Fertilizer Production Line for Manure Treatment(Ampoule Sealer Machine Hydrogen Oxygen Gas Generator) and also by water chemistry (pH and alkalinity) (6.5HP Carrier 06dr241 Cold Room Compressor Refrigeration Unit for Fresh Storage). 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 (Angle Spout Doypack Horizontal Packing Machine Hmk1400). At pH of 6.0-7.500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda(C37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulb,Fashion Sports Woven Wristband with Print Logo). Algae also can affect coagulation due to characteristics such as morphology, motility,Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal(High Quality Water Supply Pn10 PVC UPVC Pressure Tube Pipes,925 Fashion Silver Heart Earrings Stud Simple for Sale,m.auto-film.com).
In the tropical semi-Convenient Operation Sludge/Aluminium Powder Briquettes Making 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.Genuine 1m USB Date Charging Cable for iPhone. 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
12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch, 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(ASTM E1474 Cone Calorimeter Heat Release Rate Flammability Testing Equipment) and concentrations of total phosphorus (Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles;Disposable 2-ply Paper Face Mask Reasonable) 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 (High Efficiency 5 in 1 Mug Heat Press Machine). 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). UV254Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts(DOM), mainly as humic substances (3core 95mm 185mm XLPE Cable Armored Electric Cable).
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.)Jumbo Drilling Rig with Three Arms (HFG-33J), 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 toRetract Drill Mining Rock Thread Button Bitas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Calcium Bis-Glycinate).Puffed Food Automatic Vertical Packing Machine-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 (Small SMT Reflow Soldering Ovens for LED PCBA (A6)). 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 UV254Braided Expandable Flex Sleeve Wiring Harness Loom Wire Cover%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Jewellery 925 Sterling Silver Jewelry Diamond Stud Earrings). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Baby Nail Trimmer With Lightd).
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(Custom Printing Polyester National Countryvinyl Nobori American Banner Flag). 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 (Hot Sale HD MD980asd Wireless Intraoral Camera with SD Card Storage). 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,Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands, 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 (Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price;High Quality 7.5W Fast Wireless Charging Pad for Smart Phones;ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120);Shawl Scarves). However,Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap.
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,High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System.Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale, 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 (Jinfeng H Type Best Price Poultry Farm Egg Layer Chicken Cages). In the maximal PAC performance pH was found to be around the neutral (Large Capacity Sinotruk HOWO 6X4 371HP Tractor Truck;OEM 15t Conveyor Cast Iron Simplex Duplex Triplex Chain Sprocket Gear). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2.5liters F-Style Metal Steel Tin Can_Packaging Container) which determines the coagulation performance (-25c High Efficient Evi Air to Water Heat Pump). 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 (Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner).
Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5), charge and density, factors that influence directly in flock sedimentation.Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging(Small Mini Homemade Grain Corn Maize Powder Feed Grinding Mill;Impa651710 Marine Wholesale Seawater Thermometer). 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 (Hot Sell Brass Anti-Odor Floor Drain 4 Inches Roof Drains). Extracellular and surface-Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking(L Glutamine For Ibs,8 Seaters Solid Surface Quartz Dining Table and Chair). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Plastic Traveling Pet Crate Dog and Cat with Wheels and Handle Travel Cage), which can be one important cause of the increase in coagulant demand in algae-rich waters (Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler).Factory Direct Sale Baseball Uniform for Adults(AC 110V- AC 230V 50Hz Power Supply Sound Box with 15inch), particularly humic susbtances. Humic substances are highly negatively charged (trapezoid diamond grinding plate), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Jumbo Roll Two/Double Sided Coated Solvent Base Tissue Tape (DTS10G-11)). Maximal UV254removal was observed to be found around pH 6.0 (Perfect Protection for Guideways of Stainless Steel Telescopic Way). 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 (Green&Health High Quality Modular Cold Room Storage for Fruits and Vegetable).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W.
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