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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 (Garden Metal Natural Rusty Flower Decoration Product,Hot Sale Trapezoid Prepainted Galvanized Steel Roofing Sheet). As a result, several chemical methods have been applied to control P internal loading worldwide (8FT Wood Log Debarker Machine for Plywood Machinery;Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts;China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2 Storey Worker Living Block Container House Supplier). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Bioplasm Nls Hematology Biochemistry Diagostics Nls Health Analyzer),Industry Basket Washing Machine Crate Washer. 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 (Waterproof and Moldproof Marble Floor Grouting;Colourful Carbonless Paper NCR Printing Paper 50GSM/55GSM;Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hex Phillips Torx Slotted Bits Ratchet Hand Screwdriver Sets) 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 (Wdm 1.5/3/5/10/15/20m Sipu High Speed HDMI Cable 1080P Support 3D 4K with Ethernet). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom Outdoor Event Pop up Canopy Easy up Advertising Tent;High Quality Folding Training Study Table with Wheels Sf-10f;Glow in The Dark Pigment Luminescent Luminous Powder;Custom Personalized Logos Cheap Neck Printed Custom Polyester Lanyards Ribbons with ID Card Holder;Eyeglasses Microfiber Cleaning Cloth;Wear Resistant Steel with Hardness 58-62 HRC;Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi).250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price(Popular Selling Sausage Casing Making Machine;air freight China to Botswana Gaborone logistics express courier services;3G 5g 7g 10g 15g 20g/H Wall-Mounted Stainless Steel Ozone Generator;Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Sale Lfc Sand Preparation and Casting Molding Line), and it has been suggested as a lake restoration measure.
Coagulation-High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design(Vegetable Herb Garden Hand Tools with Storage Box) and also by water chemistry (pH and alkalinity) (Height Adjustable Removable Foldable Feeding Baby High Chair). 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 (Tunnel Operations Cranes). At pH of 6.0-7.3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler(ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L,Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler). Algae also can affect coagulation due to characteristics such as morphology, motility,Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block(Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant,New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale,Lab Glass Slides Manufacturers Cheap Price).
In the tropical semi-Good Price U Shape Duct Line 5 HVAC Machine-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.Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring. 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
ACP/ACP Sheet/Aluminum Composite Panel Manufacturer, 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(Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072) and concentrations of total phosphorus (Tungsten Solid Carbide Straight 4/6 Flutes Reamer;Bathroom Cabinets Vanity) 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 (Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting). 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). UV254Matt Print Foil Coffee Bags with Valve Flat Bottom Zipper(DOM), mainly as humic substances (Stainless Steel Axle Shaft).
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.)Ozone Generator Water Treatment Mineral Water Filter System, 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 toStainless Steel Slot Screen Pipe 0.3mm Slot Sizeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(16-40mm Durable Aluminum Turret).Junction Plate Connect Board Bracket Stamping Made-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 (220kv Composite Suspension Insulators for Transmission and Distribution Line). 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 UV254Reflective Police Protective Uniform for Working Vest%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.apolomed.comd).
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(PS Foam Food Container Production Line PS Lunch Box Forming Machine). 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 (Customized Precision CNC Mechanical Parts with Steel). 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,Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab, 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 (HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room;Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators;Hand Tools Mini Wire Brush Set for Construction 3PCS OEM;OSB Panel for Furniture with Dieffenbacher Machine). However,Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain.
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,Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display.Industrial Coal Fired 8 MW Hot Water Boiler Factory Price, 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 (Food Grade Titanium Dioxide F-200 Pigment). In the maximal PAC performance pH was found to be around the neutral (Silicone Rubber Pin Insulator/Polymer Composite Insulator (10kv-33kv);Customized Waterproof Backpack Canvas Laptop Bag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Medical Acupoint Patch with Sterile Wound Patch for All People) which determines the coagulation performance (Liquid Paint Machine). 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 (Carbide 4 Flutes HRC60 Blue Coated Milling Cutters).
Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer, charge and density, factors that influence directly in flock sedimentation.27.5′′ Lithium Battery Mountain Style Electric Bike(Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce;10~2500kVA (10KV) Cast Resin Dry Type Transformer with IP20 Enclosure). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (NIBP Cuff Blood Pressure Cuff Disposable of Patient Monitor). Extracellular and surface-Marine Salvage and Refloatation Rubber Airbag Roller Bags(m.dgls-tech.com,CNC Flame Plasma Cutting Machine Flame Cutting Nozzle). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Air-Cooled Refrigeration Condenser Dual Flow Unit Cooler Air-Cooled Condensing Unit), which can be one important cause of the increase in coagulant demand in algae-rich waters (14 X 14 Mesh Window Screen Aluminum Alloy Wire Netting).Girls Unicorn Costume Party Dress Tutu Kids Cute Flower Princess Pageant Carnival Clothes(Food Safety Testing Equipment for Heavy Metal in Food Analysis), particularly humic susbtances. Humic substances are highly negatively charged (cnuneed.com), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable). Maximal UV254removal was observed to be found around pH 6.0 (factory outlet excellent herbicide DIURON 80% WDG on sale). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Large Outdoor Water Park Slide/Water Turntable Amusement Equipment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates.
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