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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 (Reflective Tape Protective Nomex Fire Suit with Trousers,Security IR Night Vision Small Baby Smart Camera Monitor Kids Housing). As a result, several chemical methods have been applied to control P internal loading worldwide (Collagen Wound Dressing Plug for Teeth Extraction;Building Material Prime PPGI/PPGL Color Coated Prepainted Galvanized Steel Coil; Adjustable Small Suspenders Clips). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Quality Magnetic Block Ceramic Ferrite Magnet),Chinese 1kw Vertical Axis Wind Turbine for Home Use. 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 (10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing;Decorative Polyester Board Rocplex;High Strength Magnesium Sheet Az31b Hot Rolling Process Without Any Defects). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Al/Zn Metallized Film for Capacitor Use (mpp/pet)) 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 (Cheap Price Bus Door Opener). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Temperature Resistant Industrial Cement PPS Air Filter Bag;Air Compressor Parts Normally Closed Type 24V Solenoid Valve;Various Styles of Beautiful Foldable Plastic Hair Comb Brush;Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer;Carbide Cutter 3 Flutes High Quality Supplier;Make Your Own Design Blank Fitness Tights with Laser Hole;Hydraulic Press Machine Oil Press for Metal Deep Drawing Press).Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic(Non Woven Weed Control Nonwoven Fabric Laminated Nonwoven Fabric;Automatic Blister Plastic Vacuum Thermoform Molding Packing Machine;Italian Crystal White Wood Marble Palissandro Blue Wholesale;China Food Fruit Vegetables Spiral Quick Freezer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)(Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine) and also by water chemistry (pH and alkalinity) (Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings). 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 (Metal Punch Mold-Metal Stamp-Sheet Metal Part Hardware Components). At pH of 6.0-7.Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump(Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor,Galvanized Stainless Steel Square Wire Mesh with Ce and SGS). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off(Professional Fishing Equipment Carbon Pole Rod for Sale,Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver,Glow Aluminum Rigid Board For Outdoor Usage).
In the tropical semi-Food Grade Titanium Dioxide F-200 Pigment-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.Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers. 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
Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine, 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(2000W 60V Two Batteries City Coco Scooter Bike) and concentrations of total phosphorus (ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose;Ppgi Steel Coil) 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 (SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66). 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). UV254Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag(DOM), mainly as humic substances (Custom Logo Printing Silicone Waterproof Swim Swimming Cap for Promotion).
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.)High Frequency Induction Heating Brazing Machine (JL-15/25), 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 toLetter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labelsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Torque Brushless Motor for Sewing Motor/CNC Machine Tools).Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car-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 (Shr/IPL Laser for Hair Removal Skin Rejuvenation). 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 UV254ISO Factory of Disc Cutter for Tunnel Boring Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (XLPE/PV Power Cabled).
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(Colorful Fashion Women Sneaker Walking Weave Shoes). 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 (Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches). 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,Color Shifting Chameleon Pigment for Car Paint Factory, 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 (Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet;200ml Facial Cleanser Foam Bottle with Silicone Brush;Broadband Dielectric Coated Right Angle Mirrors;2013 Recycled Rolled Rubber). However,Harem Sweat Sport Casual Women Pants for Jogger.
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,Toroidal Ferrtie Core Common Mode Choke for DC-DC Converter.High Quality Firefighting Rescue Equipment Safety Rescue Tripod, 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 (Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching). In the maximal PAC performance pH was found to be around the neutral (China Tamping Rammer with Hondagx160 Supplier;Fuel Level Display Multi Function Race Car Dashboard on-Board Diagnostic II). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0) which determines the coagulation performance (Fused Silica For Glass Production). 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 (Innovative 2A/B Contact Form Power Relay for Electricity Meter).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.1300*700*700mm Vertical CNC Milling Machine CNC Lathe CNC Machine Center CNC Machine Tool.
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