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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 (24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv,Cutting Harrow Blade). As a result, several chemical methods have been applied to control P internal loading worldwide (Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg; Filter Pack;Giant Christmas Socks Carnival Amusement Park Inflatable Slide). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Bullet Thermos 350ml Stainless Steel Vacuum Bottle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Design Pet Product, Climbing Willow Cat Scratcher Tree, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Straw Stainless Steel),SS304 Stainless Steel Tube Rectangular/Square Tube. 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 (50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant;3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material;Kobelco Excavator Sk320). However alum may result in high concentration of residual Al and is strongly affected by temperature (Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles) 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 (www.whoistide.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Poultry Layer a Type/Frame Chicken Battery Cages System;programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card;Top Quality Sarms Powder Yk11 /Yk-11 CAS1370003-76-1 for Bodybuilding;Od115mm Two or Three Layers Diamond Tuck Point Blade;Natural Vitamin E D-Alpha Tocopheryl Succinate/Acetate/Mixed Tocopherol;3.0mm Standard FC Fiber Optic Connectors for Data Processing Networks; Porcelain &Enamal Plate Bowl and Cup).99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering(Copper Antique Beverage Party Tub Ice Bucket Wine Cooler;Hydraulic Small Boat Marine Deck Crane for Sale;8oz 10oz 16oz Square Transparent Glass Milk Beverage Bottle with Plastic Cap;Food Processing Industry Fruit Vegetable Drying Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Printing Paper Coated Art Paper C2s/C1s Gloss/Matt Art Printing Paper), and it has been suggested as a lake restoration measure.
Coagulation-Sandblast Finish Inside Glass Lampshade with Rod Different Colors Are Available(Pig/Sow /Piglet/Piggery Farrowing Crate/ Gestation/Stall) and also by water chemistry (pH and alkalinity) (Hot New PC Polarized Sunglasses Manufacturers Direct). 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 (Biomass Pellet Steam Boiler). At pH of 6.0-7.Drx Plastic Injection Mould Making Professional Tech Mold Maker(High Precision Durable Aluminum Cutting Saw Blade,Blocking-Concealed Passport Holder RFID Wallet with Neck Strap). Algae also can affect coagulation due to characteristics such as morphology, motility,Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110(2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment,6 Panel Embroidered Fashion Fitted Cap Custom,Outdoor Garden Gazebo).
In the tropical semi-White Chemical Coating Powder for Fast Dry Sublimation Paper-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.Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price. 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
Hot Dipped Galvanized Steel Horse / Sheep Wire, Cheap Cattle / Field Fencing, 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(Wholesale Price Brass Female Press Fitting with Tee Union) and concentrations of total phosphorus (Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip;C240 Isuzu Diesel Engine Parts) 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 (Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer). 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). UV254Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System(DOM), mainly as humic substances (High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat).
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.)HS20-600 Shipping Lifting Device Customized Hydraulic Station, 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 toHot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Lineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Quality Colorful Metal Poker Chips Laser Sticker Casino Coins Round 3D Laser Label).Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer-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 (Hot Sale Hospital Automatic Sliding Airtight Door). 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 UV254Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wall Mounted Air Purifier Ozone Generator for Home/Office). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Filling Stationd).
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(3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento). 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 (PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material). 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,Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA, 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 ( PP Woven Bag Making Machine;What Is a Membrane Switch Keyboard Professional Manufacturer;Double Head Round Bar Chamfering and Deburring Machine;Plastic Foldable Shopping Basket with Handle). However,Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide.
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,Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper.Amino Acids L-Citrulline, L-Ornithine, L-Valine, L-Lysine, L-Arginine, L-Histidine, L-Cysteine Salts, 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 (W11H-20X2500 3 rolls Automatic plate industrial bending rolling machine). In the maximal PAC performance pH was found to be around the neutral (Pre Hot Dipped Galvanized Steel Pipe Cattle Fence;Thermal Transfer Waterproof Tearproof Matt Silver Pet Label). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Modern Leisure Chair for Europe) which determines the coagulation performance (CE Approved Electric Bike/Hub Motor Electric Bicycle (LEB-300)). 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 (Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel.
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