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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 (Pin-Barrel Rubber Sheet Lining Extruder System Machine Production Manufacturing Line,Black Tegular Fiberglass Ceiling). As a result, several chemical methods have been applied to control P internal loading worldwide (Amino Acids L-Citrulline;Non Alkali Glassfiber Yarn for Weaving Electric Cable;EPDM / SBR /Cr/Neoprene NBR/Nitrile Silicone Natural Anti Slip Rubber Sheet). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Meat Drying). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Srz Industrial Radiator, SRL Steel-Aluminium Composite Radiator, Srq Steam Tube Radiator, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Pipe Fitting Stainless Steel Union),OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels. 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 (Eco-Friendly Unbreakable Drinking Cup Shatterproof Silicone Wine Cups for Party;China Supplier High Pressure Hydraulic Triple/Double Gear Oil Pump;Flexible DC12V/24V SMD 2835 Blue Christmas Light LED Strip). However alum may result in high concentration of residual Al and is strongly affected by temperature (Pig Breeding Equipment From China Direct Factory) 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 (Joyod Automatic Intelligent Double Head - Double Station Screw Locking Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10-100ml Paste Filling Packing Machine for Soy Sauce;Painting Steel Scaffold Planks for Construction;Outdoor Grey Aluminum Rattan Wicker Woven Beach Lounger Chair;Waterproof Reflective Padded Jacket Safety Working Clothes with Hoodies;SMT Automatic Pick and Place Machine SMD Pick and Place Machine Tp300V;Jinan Factory Atc Vacuum Table CNC Router with Cheap Price;Low Cost of 30000kg Single Driver Self-Adjustable Turning-Roll).4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System(Stainless Steel Spiral Conveyor Systems Screw Transmission Conveyor;Small Cable Reel 5m Extension Cord for Home Appliance Humidifier;Surface Led Track Light;Factory Supply OEM ODM Tungsten Carbide Seal Ring for Mechanical Seal) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Underground Water Purifying and RO Filter Treatment System), and it has been suggested as a lake restoration measure.
Coagulation-High Efficiency Complete Italy Pasta Production Line(5ton 10m Competitive Price High Quality New Telescopic Forklift) and also by water chemistry (pH and alkalinity) (Automotive Aluminum Engine Parts Low Pressure Casting). 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 (Small Used Cement Concrete Mixer Twin Shaft Mixer Made in China). At pH of 6.0-7.Monofilament Fibrillated Twist Wave Polypropylene Fiber PP Fiber for Concrete(Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C, Aluminum Hurricane Rolling Shutter). Algae also can affect coagulation due to characteristics such as morphology, motility,LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture(Waterproof Carbon Fiber Hard EVA Case for 3D VR,Rotary Machine Head Film Blowing Machine Set (PE Heat-shrinkable film Blowing Machine),High Quality Heat Resistant Muscovite Mica Sheet).
In the tropical semi-Tractor/Driving Truck/Bus/Special Car/Excavating/Excavator/Bulldozer Transport Low Bed Semi Trailer-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.4 Drawer Steel Office Vertical Filing Cabinet. 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
Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier, 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(Four Wheels Portable Electric Mobility Scooter with Lithium Battery) and concentrations of total phosphorus (High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine;Small Hand Portable Manual Cabinet Door Hole Hinge Drilling Machine) 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 (Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#)). 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). UV254Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace(DOM), mainly as humic substances (High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754)).
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.)Surgical Drape Angio Pack Angiography Drape Pack, 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 to1/4 Inch 300 Psi Rubber Hose for Compressor Airas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Crystal Clutch Bag).Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use 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 (Precision Machining Components for Hydraulic Cylinder Producing). 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 UV254Silicon Carbide Mechanical Seal with Excellent Corrosion Resistance%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Professional Salon Use Plastic Hair Coloring Comb). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (150kw Generator Headd).
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(Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging). 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 Brass Chrome Metal Dish Toilet Bathroom Fitting). 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,Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt, 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 (Kw-700 Industrial Commerical Driving Type Floor Scrubber Price;Lifting and Hoisting Industrial Manual Chain Lever Block Vt;Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set;Casement Window Lock Handle). However,NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15).
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 Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating.Sdlg B877f Backhoe Loader Price, B877f Tractor 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 (Quality FTTX Maintenance Tools Effective Fusion Splicers). In the maximal PAC performance pH was found to be around the neutral (Stainless Steel Brass Spring Check Valve (VG12.90081); Plastic Molding). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (USA American and Canada 110V UL NEMA 5-15 Power Extension Cord) which determines the coagulation performance (Zjt Bottom Price and Lightweight Color Steel EPS Sandwich Panel). 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 (Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Precision Large 3 Axis Bench Metal Milling Machine Lm1450c.
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