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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 (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile,Bh620 V2 Blade Server). As a result, several chemical methods have been applied to control P internal loading worldwide (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape;Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case;Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Supermarket Island Freezer, Island Display Freezer for Frozen Foods, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Copper Fermenter Manufacturers Cheap Price),30g 50g Plastic PP Empty White Cosmetic Cream Jar. 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 (High Quality Galvanized Pan Head Self Drilling Screw;High Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Pack;4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum). However alum may result in high concentration of residual Al and is strongly affected by temperature (Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw) 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 (Acrylic Wall Panel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes;Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating;Best Price Split Air Conditioner Stand/AC Stand;Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser;Cresyl Diphenyl Phosphate(Cdp);Jumbo Drilling Rig with Three Arms (HFG-33J);1.0 Ton Small Backhoe Crawler Mini Excavator Digger Machine for Sale).Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting(2017 Cheap China Pistol Safe Security Gun Safe Lock;Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer;3r3 smd inductor;Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle), and it has been suggested as a lake restoration measure.
Coagulation-Personalized Custom PVC USB Flash Drive for Company Promotional Gift(Siboasi Best Selling Badminton Shuttlecock Feeder Machine) and also by water chemistry (pH and alkalinity) (ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts). 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 (Medical Supply Mask). At pH of 6.0-7.Automatic Column and Boom Welding Manipulator Dlh( medical disposable clothes,Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). Algae also can affect coagulation due to characteristics such as morphology, motility,3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material(Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine, Welding Parts,Ahd 2ch Monitor System).
In the tropical semi-Auto Parts for Plastic Products Injection Mould Mold Tooling-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.2019 Smile Rabbit LED Silicone Night Light 7 Colors Desk Table Lamp For Kids. 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
Automotive Aluminum Engine Parts Low Pressure Casting, 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(Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer) and concentrations of total phosphorus (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory;15mm 18mm 20mm 30mm 40mm Bamboo Plywood for Cabinet/Worktop/Countertop/Floor/Skateboard) 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 (Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit). 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). UV254Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose(DOM), mainly as humic substances (LG936 LG938 Front End Loader Parts Gas Spring 29330011391).
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.)Public Address System High Power Range Outdoor Column Speaker, FCL-440, 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 toGood Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheetas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Lighting Metal Parts).Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games-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 ( IPS 720*1520 Display Android 9.0). 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 UV254New Product 2019 Milky White Electrochromic Smart Film%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Doorbell Pcb Assemblyd).
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(Wholesale Promotional Children Painting Apron). 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 (Poultry Farming Automatic Chicken Feeding Pan System). 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,Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp, 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 (Automatic Concrete Paving Interlocking Block Brick Making Machine;OEM Custom Cotton Twill Flat Top Military Army Hat and Cap;Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture;Hydraulic Adjustable Male Pipe Fittings 1/2*3/4 Reducing). However,Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047).
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,Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor.Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X, 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 (Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale). In the maximal PAC performance pH was found to be around the neutral (Fish Scale Shaped Waterproof Roof Tile for Roof Tile;Hydraulic Control Valve-100A Angular Stable Water Level Valve). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Direct Thermal Label with Premium Quality Adhesive Sticker Label) which determines the coagulation performance (Asbestos Braided Packing with PTFE with Oil). 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 (Wholesale Room Ozone Generator for Fruits and Vegetables).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Steel Warehouse Metallic Curved Roof Design Structure.
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