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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 (6 Panel Embroidered Fashion Fitted Cap Custom,Hy-303G Screen Label-Ribbon Printing Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Harem Sweat Sport Casual Women Pants for Jogger;Stupid Cow Indoor Coin Operated Arcade Video Vending Simulator Shooting Game Machine;Wholesale Price Brass Female Press Fitting with Tee Union). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Square LED Flat Lamp 600X600mm Made in China),Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize. 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 (Poultry Farm Equipment Feeding System Made in China;Stone Coated Roof Tile New Roofing Materials Steel Roof Shingles;Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat) 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 (Transformer Core Lamination Stacking Table). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Delight 15W Sensor+Night Sensor Solar Garden Lamp;Vertical Gas Boiler for Water Heating in Biogas Plant;Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale;Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line;Wireless Audio Video Transmitter And Receiver;Ozone Generator Water Treatment Mineral Water Filter System;Custom Running Sport Metal Medal by Soft Enamel).Factory Made Cheap Price Latching Circuit Relay for Power Control(Hot Sale Hospital Automatic Sliding Airtight Door;Wall Mounted Air Purifier Ozone Generator for Home/Office;500W 1000W Iron Laser Cutting Machine;High Speed Lead Edge Printing Slotting Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento), and it has been suggested as a lake restoration measure.
Coagulation-High Elastic Nylon Breathable Arm Elbow Sleeve for Sports(PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material) and also by water chemistry (pH and alkalinity) (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll). 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 (RGB SMD Outdoor Programmable LED Video Board Display P10 Module). At pH of 6.0-7.Ladies Fashion PU Leather Mini Backpack for Girles(P6.25 Interactive Dance Floor LED Display Screen, PP Woven Bag Making Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Price Diesel Water Pump for Mine Dewatering(What Is a Membrane Switch Keyboard Professional Manufacturer,Double Head Round Bar Chamfering and Deburring Machine,Good Corrosion Precision Cemented Carbide Roll Rings Carbide Sealing Ring).
In the tropical semi-Most Popular Android Satellite Receiver Android DVB S2 Cccam-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.3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist. 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
Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13, 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(Thermal Transfer Waterproof Tearproof Matt Silver Pet Label) and concentrations of total phosphorus (Modern Leisure Chair for Europe;16 Bar Air Compressor) 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 (Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa). 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). UV254Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine(DOM), mainly as humic substances (New Baking Tool Creative Customized Silicone Toast Cake Mold).
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 Density Wood Grain Fiber Cement Board, 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 toCarbon Steel Heavy Structural Flat Washers Grade 10 DIN6916 Washersas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Stainless Steel Sheet Metal Ss V Grooving Machine 8 Meters for Small Bending Angle).Waterproof Spunbonded Flame Retardant Fabric for Function Textile-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 (Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars). 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 UV254The Factory Sells Low Price and High Quality Desulfurizer Powder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (C-Type 2 Piece Tin Can Making Punch Press Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Ball Valve Partsd).
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(Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control). 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 (Custom Ductile Iron Casting Parts Gray Iron Sand Casting). 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,Antique Bronze Household Furniture Cupboard Shutter Drawer Knobs Pulls Handle, 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 (Engineering Plastic Material;SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings;GMP Certified Collagen Softgel for Fish Collagen;Spring Mattress Twin). However,Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser.
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,Factory Customized Marathon Athletics Football Awards Medallion Metal Medal.Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies, 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 (26000lm 200W LED High Bay Lamp Fixture for Gym House Factory). In the maximal PAC performance pH was found to be around the neutral (Luzhong-700 70HP 2WD Two Wheel Drive Farm Tractor;Hjd-J3 Double-Position Semi-Automatic Heat Transfer Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Corn Starch Foam Biodegradable Frozen Food Packaging Tray) which determines the coagulation performance (High Brightness 12inch LCD/LED Open Frame Touch Screen Monitor). 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 (Good Quality of 60t/D Wheat Flour Milling Plant).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Aluminum Height Adjustable Walking Cane (SC-CR58-67).
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