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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 (Decorative Polyester Board Rocplex,Hot Sale Type Ice Cube Fertilizer Charcoal Packing Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects;High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet);High Temperature Resistant Industrial Cement PPS Air Filter Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Air Compressor Parts Normally Closed Type 24V Solenoid Valve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (5 Axis Cnc Machining Services),NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15). 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 (Various Styles of Beautiful Foldable Plastic Hair Comb Brush;Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer;Make Your Own Design Blank Fitness Tights with Laser Hole). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hydraulic Press Machine Oil Press for Metal Deep Drawing Press) 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 (Stainless Steel Hex Socket Cup Head Bolt Machine Screw M1.6-M20). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric;Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine;China Food Fruit Vegetables Spiral Quick Freezer;Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine;Aluminum Metal Roll Up Doors;Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings).China Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating(Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor;Galvanized Stainless Steel Square Wire Mesh with Ce and SGS;Chain Link Fence Zinc Coating;Professional Fishing Equipment Carbon Pole Rod for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver), and it has been suggested as a lake restoration measure.
Coagulation-Sdlg B877f Backhoe Loader Price, B877f Tractor for Sale(Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester) and also by water chemistry (pH and alkalinity) (Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628)). 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 (m.swinysteel.com). At pH of 6.0-7.Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser(2000W 60V Two Batteries City Coco Scooter Bike,ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose). Algae also can affect coagulation due to characteristics such as morphology, motility,Supporting DDR4 RAM Intel Core I5 Mini PC Computer(Rebar Splicing of Reinforcement Bars Complying with Aci-318,Multi Span Venlo Type Agriculture Production Glass Greenhouse,Ce Certificate Plywood Veneer Lathe Manufacture).
In the tropical semi-Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon-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.Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample. 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
Precision Large 3 Axis Bench Metal Milling Machine Lm1450c, 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(Outdoor Full Color P6mm Front Maintenance LED Display) and concentrations of total phosphorus (Water Treatment Chemicals RO Antiscalant Acidity for Groundwater;high quality TPU material for garments) 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 (China Factory Gk35 Sewing Machine for Bag with Conveyor). 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). UV254Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO(DOM), mainly as humic substances (Refrigerant R134A with Refillable Tped Approved Cylinder).
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.)Double Deck High Quality Aluminum Pontoon Boat 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 toColorful Fashion Women Sneaker Walking Weave Shoesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Stainless Steel China Poultry Animal Bone Crusher Grinder Machine).Outdoor Garden Furniture Knock Down Aluminum Polywood End Table (73443-X)-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 (High Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire). 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 UV254D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet). 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 Flat Die Wood Pellets 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(Broadband Dielectric Coated Right Angle Mirrors). 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 (Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching). 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,Liquid Laundry Detergent Small Single Bag Packing Machinery, 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 (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;4 Inch Galvanized Steel Pipe). However,Fashionable Sports Outdoor Safety Shoes with Composite Toe.
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,China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder.Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets, 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 (Working Safety Glove with Latex Coating for Guangzhou Sample). In the maximal PAC performance pH was found to be around the neutral (AAA Quality Mobile Phone LCD for iPhone 6s Touch Screen;Reflective Police Protective Uniform for Working Vest). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Junction Plate Connect Board Bracket Stamping Made) which determines the coagulation performance (GRP Anti Corrosion Chemical Storage Tank Vessel Container). 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 (High Precision Machining Adjustable Timing Cam Gear Pulley for Motorcycle).
Hip-Hop Streetwear Custom Brand Fashion Man Hoodie, charge and density, factors that influence directly in flock sedimentation.Boiler Seamless Steel Tube En10216-216mo3, Steel Pressure Tube Pipe 25crmo4(China PS Printing Plates Positive PS Plate Maker;Extra White Masterbatch 60% Anatase TiO2 for PE Films). 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 (Customized Food Storage Glass Mason Jar Glass Container with Metal Lid). Extracellular and surface-Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine(Zxx-C1325 Automatic CNC Glass Cutting Machine Machinery Waterjet Machine,China Factory Hollow Pneumatic Piston Rod). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Armor Thermocouples / Thermal Resistance Temperature Sensor), which can be one important cause of the increase in coagulant demand in algae-rich waters (Classical Gym and Commercial Fitness Equipmen Decline Bench T40).Rgt-16-Ye Ruler Baby Scale 16kg, Mechanical Infant Scale(Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368), particularly humic susbtances. Humic substances are highly negatively charged (Home Security Factory & Manufacturer), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube). Maximal UV254removal was observed to be found around pH 6.0 (Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange). 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 (Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom.
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