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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 (New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor,Battery Tester). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem;Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Lab Pipette Tips with Good Quality Low Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (18*16 Waterproof Plisse Pleated Polyester Insect Screen Mesh),Poultry Farming Automatic Chicken Feeding Pan System. 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 (Ce Approved Disposable Paper Mask;Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage;Single Color Twill Tapes Automatic Screen Printing Machine Supplier). However alum may result in high concentration of residual Al and is strongly affected by temperature (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set) 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 (Custom Tray). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses;Top Quality Cleaning Cloth Microfiber Hair Salon Towel;Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine;Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair;Manufacturer Weed Smoking Accessories DAB Smoke Cigar Silicone Ashtray Rubber Ash Tray;HPMC 200;Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump).Water Resistant Rubber Gasket for Industry(210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock;Wholesale Baby Shoes Kids Boy Wear LED Flashing;2006 Jeep Grand Cherokee Key Fob;Low Price & High Quality Stainless Steel X-ray Lead Door) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Carbon Steel Wire Lead Patenting Phosphate Production Line), and it has been suggested as a lake restoration measure.
Coagulation-Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer(Custom China Supplier Stainless Steel Precision Casting Throttle Valve) and also by water chemistry (pH and alkalinity) (Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter). 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 (Mobile 150 Ton Hydraulic Cylinder). At pH of 6.0-7.PVC Gas Hose, LPG Hose Best Choice for Home Use(Health Food Krill Oil Softgel for Antioxidation,Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan(E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits,Farrowing Crate Galvanized Swine Farrowing Crates,Print Bedding Fabric).
In the tropical semi-Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress-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.Best Polystyrene Sandwich Board Manufacturer. 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
Outdoor WPC Wood Plastic Composite Fence Board with High Quality, 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(Competitive Price Corrugated Tubing with Braid Layer) and concentrations of total phosphorus (Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer;Electrical Control Panel Board) 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 (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor). 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). UV254Full Automatic Chocolate Holding Tank with Water Jacket(DOM), mainly as humic substances (A76 Nordic Living Room Dining Room Furniture).
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.)Professional Supplier of Hot Rolled Steel U Channel, 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 toStainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Interlocking Turf).22mm 2no2nc Metal on off Start Button Power Push Button Switch-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 (Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). 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 UV254Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PCB Fab And Assemblyd).
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(Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel). 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 (Free-Maintenance Motor Design White Light PTZ Security Cameras). 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,Beauty Equipment Face Lifting Hifu Equipment, 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 (UPVC Rigid Water Supply Drain Pipe Production Line;High Temperature Multi-Jet Ultrasonic Heat Measure Meter;Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine;Stainless Steel Bathroom Vanity Cabinet). However,Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008).
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,LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse.19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU, 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 (OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092). In the maximal PAC performance pH was found to be around the neutral (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003);Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar) which determines the coagulation performance (Width Of Corrugated Roof Sheet). 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 (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Manufacturer Woven Patches and Customized Woven Badge.
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