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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 (Colorful Fashion Women Sneaker Walking Weave Shoes,Luxury Passenger Elevator Lift for Hotel / Hospital). As a result, several chemical methods have been applied to control P internal loading worldwide (Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches;DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction;High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,2.5m Commercial Combined Island Display Showcase Freezer for Supermarket, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Engineers Available To Service Overseas Pvd Coater),Support TF Card / Bluetooth / WiFi / LAN 2GB + 32GB 7 Inch Pipo X8 PRO TV Box Style Mini PC. 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 (200ml Facial Cleanser Foam Bottle with Silicone Brush;Broadband Dielectric Coated Right Angle Mirrors;Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Tamping Rammer with Hondagx160 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 (Wholesale Cheap Insulated Picnic Cooler Box for Outdoor Yeti Cooler for Fishing and Hunting). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fuel Level Display Multi Function Race Car Dashboard on-Board Diagnostic II;Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0;Innovative 2A/B Contact Form Power Relay for Electricity Meter;Cheap Outdoor Patio Rattan Hotel Furniture;Piston Rod Plunger Cylinder;Working Safety Glove with Latex Coating for Guangzhou Sample;AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen).Small Travel Backpack Foldable Camping Outdoor Bag(Reflective Police Protective Uniform for Working Vest;Junction Plate Connect Board Bracket Stamping Made;Flash-Charge Type-C Cable for Mi Mobile Phone;High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China PS Printing Plates Positive PS Plate Maker), and it has been suggested as a lake restoration measure.
Coagulation-China Factory Ms ERW Welded Cold Rolled Black Carbon Square Rectangular Hollow Section Steel Pipe(Extra White Masterbatch 60% Anatase TiO2 for PE Films) and also by water chemistry (pH and alkalinity) (Customized Food Storage Glass Mason Jar Glass Container with Metal Lid). 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 (Customize Logo Soft Rubber Bar Mat for Promotion). At pH of 6.0-7.Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy(China Factory Hollow Pneumatic Piston Rod,Armor Thermocouples / Thermal Resistance Temperature Sensor). Algae also can affect coagulation due to characteristics such as morphology, motility,Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade(Classical Gym and Commercial Fitness Equipmen Decline Bench T40,Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368,Fruit Tea Production Line).
In the tropical semi-Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System-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.Galvanized Wire Rope Sling with Eyes at Both Ends. 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
China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose, 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(Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch) and concentrations of total phosphorus (Steel Frame Fabricated Bird Poultry Broiler Farm Shed Building;Small 20kg Spiral Hobart Biscuit Spar Wheat Dough Mixer Machine for Tortilla) 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 (200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter). 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). UV254XCMG Official 150 Ton Rough Terrain Crane Rt150(DOM), mainly as humic substances (Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric).
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.)China Factory Fluorescent Neon Powder Pigments, Cosmetic Fluorescent Pigment Powder Manufacturer, 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 to275ml Ice Beer Cocktail Carbonated Drink Glass Bottleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(18 LED Car Camera 150 Degree Waterproof for Truck Bus).1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve-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 (Steel Warehouse Metallic Curved Roof Design Structure). 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 UV254Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Drum Sand Rotary Dryer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Pigment Removal 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(China Factory Entry Security Type Steel Door with Low Price). 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 Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS)). 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,Osyea 2019 Outdoor Power Solar Garden LED Street Lamp, 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 (Latest Popular off Road Electric Citycoco 1500W 2018 Scooter;China Factory Wholesales Common Wire Nails Common Nails High Quality Low Price Polished Iron Nail;Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine;Prepainted Galvalume Steel Coil Full Hard ASTM A792 G550 914 940 1220 mm Coil). However,Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs.
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,Stainless Steel Handrail Long Bar Holders for 12mm Pipe.Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator, 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 (Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780). In the maximal PAC performance pH was found to be around the neutral (Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046);Medical High Precision Aluminum Alloy Parts Machining for Medical Service). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Single-Acting Hydraulic Cylinder for Dump Truck) which determines the coagulation performance (Anvil Cylinder). 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 (Best Price Slewing Ring Bearings for Crane Wind Turbine System).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps.
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