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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 (Custom Outdoor Event Pop up Canopy Easy up Advertising Tent,Home Use Multi Cavity Cold Runner Injection Mould Plastic Product). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wear Resistant Steel with Hardness 58-62 HRC). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Modern Style Home Furniture Set Metal Stainless Steel Outdoor Kitchen Furniture, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automatic Leather Panel Cutting Machine),Good Price High Torque 12mm Low Speed Small Geared Motor. 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 (Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi;Popular Selling Sausage Casing Making Machine;air freight China to Botswana Gaborone logistics express courier services). However alum may result in high concentration of residual Al and is strongly affected by temperature (Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle) 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 (Car Magnetic 5m Rg58 Coax Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Good Sale Lfc Sand Preparation and Casting Molding Line;Vegetable Herb Garden Hand Tools with Storage Box;Height Adjustable Removable Foldable Feeding Baby High Chair;ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L;Bella Diamond Microdermabrasion Machine Beauty Equ;Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler;Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant).Glass Mike Bottle 200ml 250ml with Screw Cap Straws(New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale;Built-in Camera Shoot Photo Video Recording Multi Function Night Vision Telescope;Wholesale Price Integrated LED 20W 40W 60W All in One LED Solar Street Light;High Quality Sky Indoor Mesh Trampoline Zone Park with Cheap Prices) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Waterproof Hammock Pet Seat Cover in Car for Dog Blanket by 600d Ad18072), and it has been suggested as a lake restoration measure.
Coagulation-Full Automatic Egg Tray Manufacturing Machine(Tungsten Solid Carbide Straight 4/6 Flutes Reamer) and also by water chemistry (pH and alkalinity) (Custom Industrial Field Block Ferrite Rare Earth Magnet). 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 (Stainless Steel Cutting Board Durable Metal Chopping Board). At pH of 6.0-7.4 Stage Ture HEPA Filter Ionic Air Purifier with 4 Fan Speed(7,Sleeve Block Truss for 290mm/400mm Aluminum Spigot Roof Lighting). Algae also can affect coagulation due to characteristics such as morphology, motility,1200*2200mm Black Powder Coated Dutch Barn Stall Door(Stainless Steel Axle Shaft,Suitcase Belts Continuous Dyeing and Finishing Machines,Car Truck Sport Manual Mt Drift Gear Shift Knob).
In the tropical semi-Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer-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.120 AMP Circuit Breaker Trolling with Manual Reset, 12V- 48V DC, Waterproof (120A). 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
Swing Check Valve Stainless Steel Type Non Return Valve, 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(Stainless Steel Slot Screen Pipe 0.3mm Slot Size) and concentrations of total phosphorus (Ytpd173r140-4.0 Ultrasonic Focusing Piezoceramic Transducer for Beauty;Cold Sealing Adhesive Packing Roll Film) 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 (Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware). 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). UV254Padded and Comfortable Cushion Stainless Steel Carmeno Velvet Dining Chair(DOM), mainly as humic substances (Customized CNC Machining Checking Fixture for Automotive Bracket).
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.)Stainless Steel Miniature Tapered Roller Bearings 32020 for Heavy Truck / Tractor, 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 toOutdoor LED Street Pole Advertising Business Double Sided LED Signsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ultra Thin Soft TPU Transparent Mobile Phone Case for iPhone Xs/ Xs Max Clear Back Cover).Women Footwear Ballerina Casual Shoes With High Quality-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 (Hand Tools Mini Wire Brush Set for Construction 3PCS OEM). 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 UV254Astma312 TP304/Uns30400/X5crni18-10 Seamless Stainless Steel Round Hollow Bars%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Food Grade Titanium Dioxide F-200 Pigment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Elegant Popular Design Cup Set with Saucer for Hotel&Restaurantd).
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(Customized Waterproof Backpack Canvas Laptop Bag). 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 (Medical Acupoint Patch with Sterile Wound Patch for All People). 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,Stationary Asphalt Mixing Plant From 100tph to 400tph, 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 (10~2500kVA (10KV) Cast Resin Dry Type Transformer with IP20 Enclosure;NIBP Cuff Blood Pressure Cuff Disposable of Patient Monitor;CNC Flame Plasma Cutting Machine Flame Cutting Nozzle;Automatic Steel Floor Deck Roll Forming Machine). However,380V50Hz Hitachi Scroll Compressor 503dh-83c2 with Gas R22.
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,Chocolate High Speed Automatic Feeding and Packing Line.China PS Printing Plates Positive PS Plate Maker, 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 (Air-Cooled Refrigeration Condenser Dual Flow Unit Cooler Air-Cooled Condensing Unit). In the maximal PAC performance pH was found to be around the neutral (14 X 14 Mesh Window Screen Aluminum Alloy Wire Netting;Food Safety Testing Equipment for Heavy Metal in Food Analysis). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable) which determines the coagulation performance (LED Electric Mosquito Fly Insect Trap Killer Mosquito Killer). 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 (factory outlet excellent herbicide DIURON 80% WDG on sale).
Biobase -10~-25 Degree Upright Style Single Door Lab Deep Freezer, charge and density, factors that influence directly in flock sedimentation.Very Cute Baby Gift Packing Shopping Carrier Paper Bag(Large Outdoor Water Park Slide/Water Turntable Amusement Equipment;Pond Electric Copper Wire Clean Water Pump with European Plug). 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 (Customized Disposable BBQ Bamboo Round Stick and Skewers.). Extracellular and surface-Eco Friendly Biodegradable Soup Bowl Food Container(500W 1000W Fiber Source Handheld Laser Welding Machine 800W,Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Quality Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment), which can be one important cause of the increase in coagulant demand in algae-rich waters (Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line).from China to Brazil Brasilia reliable low rates Shipping Logistics Air Freight Forwarder(CNC Fiber Laser Marking/Engraving Engraver for Metal and Nonmetal), particularly humic susbtances. Humic substances are highly negatively charged (White Plastic Flexible Downspout Extension PVC Pipe), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill). Maximal UV254removal was observed to be found around pH 6.0 (High Drying Efficiency Wood Sawdust Dryer for 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 (Exported Screw Eye Ground Anchor for Electric Fence Using).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.IPS No. 6 Dtp Automatic Smart Wrist Watch 2019.
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