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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 (Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer,Carrageenan Thickener Ham Sausage Improver). As a result, several chemical methods have been applied to control P internal loading worldwide (Puffed Food Automatic Vertical Packing Machine; Customized Fancy Printing Adhesive Paper Label Sticker;TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (A76 Nordic Living Room Dining Room Furniture). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cleaning Fiber Optic Connectors High Quality Supplier),Organice Ball Fertilizer Granulation Machine. 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 (Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System;90ml Cool Designer Perfume Glass Bottle with Surlyn Cap). However alum may result in high concentration of residual Al and is strongly affected by temperature (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle) 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 (Customized Glass 100ml Perfume Spray Bottle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fr-218 BOPP Packing Tape Slitting Rewinding Machine;Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery;Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;Squeeze Mop;Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line;Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel).Pre-Cut Bath Shower Treads, Clear Textured Slip Resistant Strips, 2 Inch X 12 Inch Rounded Corners(Free-Maintenance Motor Design White Light PTZ Security Cameras;Plastic Cover Aluminum A60 7W E27 LED Global Bulb;Cement Mortar Brick Wall Plastering Rendering Machine;Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (UPVC Rigid Water Supply Drain Pipe Production Line), and it has been suggested as a lake restoration measure.
Coagulation-Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing Machine(High Temperature Multi-Jet Ultrasonic Heat Measure Meter) and also by water chemistry (pH and alkalinity) (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine). 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 (Scooter With Hand Control). At pH of 6.0-7.Car Cooling Spare Parts Compressor Magnetic Clutch(OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092,Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sale Farm Implement 1bzd Series Tractor Mounted Hydraulic Opposed Hydraulic Disc Harrow(Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine,ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar,Gaming Chair).
In the tropical semi-Amino Acid Magnesium Chelate for Organic Fertilizer-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.EPS100 Nts100 Xns100 Common Rail Injector Test Bench. 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
High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration, 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(Gravity Metal Separator Detector for Plastic Pellets) and concentrations of total phosphorus (Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002;Automatic X6 Cutting 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 (New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice). 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). UV254ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe(DOM), mainly as humic substances (High Tensile Sharp Razor Barbed Wire for Security Fencing).
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.)LED Dancing Wing Props Halloween Christmas Party Supplies, 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 toCustom Printed Luxury Black Paper Gift Carry Shopping Packaging Bagas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Mkf2110 CNC Grinder Compound Multi-Function ID & Od CNC Machine).AAC Autoclaved Aerated Concrete Brick Making Machine, AAC Plant Solution-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 (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace). 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 UV25415.6 Inch LED Backlight Wide Screen HD LED TV Ce CB%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (ESD Bakelite Sheet/ Anti-Static Phenolic Paperd).
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(Automatic Mango Juicer Filling Machine / Canned Juice Production Line). 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 (Low-Cost Tree Stump Crushing Machine with Widely Using). 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 Crane Electrical Overhead Cable with Steel Wire, 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 (Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z;Lightweight New Design Girl Fashion Bags Children School Backpack;Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier;Pressurized Solar Thermal Heat Pipe Collector Solar Heating Water Heater). However,Safety Bike for Cool Design Children Bike/Bicycle.
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,CCTV Security System Projects IP Camera Factory Hikvision IP Camera.Eco-Friendly Euro Plastic Container with Lid, 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 (New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price). In the maximal PAC performance pH was found to be around the neutral (Round 10W LED CCT Tuneable Dimmable Down Lights;Customize Cartoon Printing Logo Brand Silicone Swim Cap). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Citycoco) which determines the coagulation performance (Aluminum Foil Reflective Coated Anti-Glare Woven Fabric). 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 (Type F High-Rise Clip Drive/Worm Hose Clamp).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,.
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