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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 (Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps,Personal SPA Paraffin Bath Paraffin Wax Heater with Temperature Control). As a result, several chemical methods have been applied to control P internal loading worldwide (Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith;Wallbox Socket Type 2 16A 3.7kw Single Phase EV Charging Point EV Charger for Electricvehicles;Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Rice Cracker Core Filling Snacks Food Making Machinery). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,P810 Indoor & Outdoor Single Color Vehicle LED Display Module, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hotel Lobby Copper Wall Sconces Lamp with Glass in Copper Color),Factory Supply Customized Sintered Inner Gear Rotor by Iron Alloy Powder. 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 (Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water;Customized Speed 110V-220V 60X60X25mm Axial Brushless Cooling AC Ec Powerful Fan;2017 The Newest Moringa Leaf Drying Machine/Black Pepper Dryer Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Home Security PRO Hunter RF Signal Detector Detect Bugging Devices in Your Home) 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 (Wholesale Brazilian Human Hair Body Curly 13X4 Transparent Swiss Lace Frontal). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Frozen Food;Good Quality R134A Refrigerant Copper Tube Fin Heat Exchanger;Customized Plastic Injection Mould Products Industrial Parts Plastic Cross Pipe;High Pressure Rubber Hydraulic Hose Assembly;Bottom Loading Hose;China Wholesale Hot Sale Microfiber Car Cleaning Towel;9-80V Laser Red Zone LED Work Safety Lights for Forklift Truck).High Quality Rogers Athletic PRO Squat Equipment(Triangle Plastic Checkout Counter Divider Bar with Logo Printed;Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking;Eco-Friendly Custom Foot Compression Sport Socks;Digital Control Gold Powder Coating Machine for Metals) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion), and it has been suggested as a lake restoration measure.
Coagulation-CNC OEM ODM Customized Car Housing Parts Machining Parts(Custom C3 C5 Ground Miniature Ball Screw 0802) and also by water chemistry (pH and alkalinity) (Log Debarker Veneer Rotary Peeling 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 (Black Wood Grain Laminated MDF Melamine Board). At pH of 6.0-7.4 Seat Lead Battery Powered Electric Beach Buggy Cart (DN-4)(Real-Time GPS Padlock Container Tracker GPS Tracking Car/Truck Fleet Management,Outdoor Food Truck Mobile Food Car for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Free-Maintenance Motor Design White Light PTZ Security Cameras(Durable Soft Polishing Wheel for Polishing Wood and Plastic,Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe,Solid Steel Electronic Safe Box for Home and Office (G-43ES)).
In the tropical semi-High Speed HDMI to HDMI Cable 1.4 Version 1080P 3D Standard 2.0-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.ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose. 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
Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt, 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( 12V- 48V DC) and concentrations of total phosphorus (Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White;Jetting Water Truck) 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 (Ocs-Y 10 T 20 Ton Crane Scale Load Cell 10000 Kg Crane Scale). 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). UV254IP65 60W Solar LED Street Light with WiFi Camera(DOM), mainly as humic substances (Acupressure Shakti Massage Mat Kit with Pillow and Carry Bag).
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.)Popular Selling Sausage Casing Making Machine, 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 to2019 Mini I9/I9s Tws Stereo Wireless Headphones Blue Tooth Sport Earphone Earbudsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(RF Shielding MRI Door with Brass Frame for RF Cage).Colorful Aluminum Cream Jar for Cosmetic Packaging-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 (2019 New Designed High Quality Playground Indoor Kids′ Plastic Slide). 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 UV254Top Quality Disposable Dental Surgical Suction Sterile Aspiration/ Aspirator Tips%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (JIS G3441 Machining and Structure Alloy Steel Pipe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Prime Quality PVC Welded Wire Mesh Fence Nettingd).
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(Agricultural Drip Irrigation Rain Gun System). 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 (Full Automatic Old Car Tyre Recycling Machine /Side Wall Cutter). 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 Speed Lead Edge Printing Slotting Machine, 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 (Sany 60 Tons Stc600s Hydraulic Crane Project Truck Crane;Prime Quality Cold Rolled Steel ERW Tube Mill;5 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe;Waterproof Bamboo Pattern Wallpaper for SPA). However,Good Sale Lfc Sand Preparation and Casting Molding Line.
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,High Glossy/Matt/Embossed/UV/Natural Wood Veneer Faced Melamine Laminated Colored MDF for Furniture.Key Chain Metal Key Rings Acrylic Key Bag Holder, 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 (SRS Painting Green Color 10ml Thick Glass Roller Ball Bottle). In the maximal PAC performance pH was found to be around the neutral (Alumina Ceramic Shafts Al2O3 Ceramic Plungers;Laminated Curtain Wall Glass with Colored PVB Film). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Frequency Induction Heating Brazing Machine (JL-15/25)) which determines the coagulation performance (Big Window Light Steel Frame Holiday Resort House). 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 (Hot Sale Copolymer Coated Aluminum Foil Tape for Cable).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fuel Level Display Multi Function Race Car Dashboard on-Board Diagnostic II.
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