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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 (Cheap Price Woodfree Offset Writing Printing Paper,Light Masts). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality XCMG Truck Mounted Crane Sq3.2sk1q/K2q in The Philippines;Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack;Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New TF Card Head Fone Retractable Audifonos PARA cellular Bluetooths Headphone). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Quality Water Supply Pn10 PVC UPVC Pressure Tube Pipes, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China rubber mud suction hose),Metal Mesh Screen for Decorative Architectural Metal Mesh for Partition. 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 (Fancy Corn Starch Disposable Round Plate with Stripe for Party;Ce Approved Disposable Blood Bag for Ozone Blood Therapy;Coconut Shell Activated Carbon for Drinking Water Treatment). However alum may result in high concentration of residual Al and is strongly affected by temperature (100ml Boston Round White Matte Plastic Pet Nursing Care Toner Bottle) 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 (China Hose Clamps). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Digital Pistol Safe Box / 4-Number Digital Safe Box;China Manufacturer Plastic Material Black Masterbatch PE PP Resin;Braided Nylon Aluminum Magnetic Micro USB Cable for Smart Phone;China Manufacturer Single Use Blue Hospital Reinforced Surgical Gown with Knitted Cuff;6630 Dmd Factory OEM/ODM Product;Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine;Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games).1/2 Inch Brass Stem Handwheel Gate Globe Valve(Cmyk Printed Colorful Logo Wholesale Luxury Fancy Art Paper Shopping Gift Bag with Ribbon;Ductile Iron Grooved Rigid/Flexible Couplings Fire Fighting Pipe Fittings;Single Head Electric Shaver;Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Horizontal Flat Bed CNC Metal Lathe (CAK6140 CAK6150)), and it has been suggested as a lake restoration measure.
Coagulation-Red Enamel Cast Iron Fondue Pot with Forks(2019 LCD PRO Hot Ionic Straightening Brush (Q20)) and also by water chemistry (pH and alkalinity) (SMD P4 Outdoor Full Color Rental HD LED Display). 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 (Nylon Fabric Braided Sync USB Charge Cable for iPhone & Android Phone). At pH of 6.0-7.Wg9130583017 Sino Truck Spare Parts Combination Switch(Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine,Wicker Willow Flower Garden Gardening Basket). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board(New Fitness Commercial Exercise Spinning Bike,Pressure Sensor Water Level Pressure Transmitter,China Double Glazed Door).
In the tropical semi-IP65 8W Outdoor Integrated LED Street Light Solar Lamps-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.Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting. 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
Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow, 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(Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube) and concentrations of total phosphorus (Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles;Astar Catering Equipment Counter Top Luxury Gas 2-Tank Deep Fryers) 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 (New Arrival Household Self-Washed Flat Mops Cleaning). 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). UV25490L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage(DOM), mainly as humic substances (Chinese Furniture Outdoor Garden Furniture Aluminum Sofa Sets).
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.)Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards, 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 toCustomized Cutting Tool Solid Carbide Tool Taps (TS-100002)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cylindrical Filter Element Supplier & Factory).Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer-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 (Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable). 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 UV254Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Diecast Import Cars Supplier & Manufacturerd).
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(Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller). 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 (RFID and Remote Controller Small Electronic Lock with Password). 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,High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader, 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 (Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing;Electrically Heat Furnace Prime Quality Radiant Tubes;Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window;Bottle Glass 30 Ml). However,17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack.
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,CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,.Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700, 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 (Colored Corrugated Steel Roofing Sheet with ISO9001). In the maximal PAC performance pH was found to be around the neutral (Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8);Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (FRP Fiberglass Underground Septic Tank for Effluent Treatment) which determines the coagulation performance (m.yasentag.com). 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 (96 Pin IDC Cable Connector D-SUB Connector SCSI Type).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Gear Operated Cast Iron Wafer Type Butterfly Valve.
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