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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 ( Tiger Skin Yellow Cement Based Wall Stone Veneer,4mm Smoke Grey Tinted Glass). As a result, several chemical methods have been applied to control P internal loading worldwide (Watertight Hi-Viz Yellow Thermal Latex Gloves Safety Work Glove;Hot Sale Industry Titanium Disc/Titanium Alloy Disc;Android Handheld Barcode Scanner Industrial PDA). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Car Cooling Spare Parts Compressor Magnetic Clutch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fiber Laser Marking Machine for Cutting Metal Foil Optical Laser System Including Computer),Hot Sale Farm Implement 1bzd Series Tractor Mounted Hydraulic Opposed Hydraulic Disc Harrow. 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 (HDF Mould Skin Doors Wooden with Cheap Prices for Kid Rooms;Easy Maintenance Automatic 6000PCS/H Egg Tray Machine;New selling OEM quality strong magnet segment arc ferrite magnet for motor). However alum may result in high concentration of residual Al and is strongly affected by temperature (Low Price 10mm 210rpm Small Speed Reducer Gearbox) 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 Modular Sport Flooring). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (LED Car Work Light of 51W 6inch with off-Road Spot Beam;50-500μ M Pet Film for Electrical Insulation (6023D);Manufacturer Bimetallic Parallel Twin Screw Barrel for Extruder;Color Shifting Chameleon Pigment for Car Paint Factory;wet use vacuum brazed diamond drill bit;Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet;Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe).Amino Acid Magnesium Chelate for Organic Fertilizer(18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display;18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material;Bread Baking Oven High Quality Supplier;LSR Injection Mold Tooling for Medical Nipple) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing), and it has been suggested as a lake restoration measure.
Coagulation-EPS100 Nts100 Xns100 Common Rail Injector Test Bench(Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)) and also by water chemistry (pH and alkalinity) (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw). 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 (Downpipe Roll Forming Machines). At pH of 6.0-7.High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration(Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag,Private Label Washing Laundry Powder Detergent). Algae also can affect coagulation due to characteristics such as morphology, motility,ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe(New Product 2019 Milky White Electrochromic Smart Film, Transparent Acrylic Double-Sided Tape,Cold Bending Stamping Welding Steel Parts).
In the tropical semi-LED Dancing Wing Props Halloween Christmas Party Supplies-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.AAC Autoclaved Aerated Concrete Brick Making Machine, AAC Plant Solution. 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
15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB, 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(Easy to Use Mobile Filter Unit for Light to Medium Welding) and concentrations of total phosphorus (8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line;Australia Trailer Lights Cable Connect 7pin 12V Socket Flat Plug) 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 (Topkit Tower Crane Rct6011-6 for Construction Building). 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). UV254Auto Crane Electrical Overhead Cable with Steel Wire(DOM), mainly as humic substances (Motion Sensor Light Stick Closet Light Wall LED Night Light).
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.)Safety Bike for Cool Design Children Bike/Bicycle, 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 toWholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dogas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(chinajssl).CCTV Security System Projects IP Camera Factory Hikvision IP Camera-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 (Plastic PVC/WPC Granulator Die Face Cutter Extruder Machine). 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 UV254Eco-Friendly Euro Plastic Container with Lid%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Flue Gas Desulfurizationd).
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(Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult). 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 (Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring). 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,2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′, 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 (Hot Sale Bamboo Toothbrush in Flate Simple Design;Honed St52 Piston Tube for Hydrau; IC Cylinder;EV850m CNC Machine High Precision Vertical Machining Centers Price;Custom Printed Luxury Gift Shopping Big Strong Paper Bags). However,Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights.
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,Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration.Standard Air Small Sandblaster for Construction Machinery Cleaning, 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 (Stainless Steel Welded Wire Mesh BBQ Grill Grate/Mesh for Cooking). In the maximal PAC performance pH was found to be around the neutral (NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15);Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers) which determines the coagulation performance (Motor Dc). 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 ( Cosmetic Fluorescent Pigment Powder Manufacturer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood.
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