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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 (Aluminum LED Outdoor Solar Lawn Light for Garden,Belt Drive Milling Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price;Anti-High Corrosion and Wear Resistance Carving Zirconia Ceramic Car Rotor;Multi-Functional Toys Packaging Machine for Packaging of Children Toys). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Bubble Cloth Seersucker Honeycomb Style Polyamide Knit Bikini Fabric, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2018 Summer New Design Natural Stone Shell Bracelet with Heart Pendant),Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case. 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 (Tubular Polyethylene Plastic Film Blowing Machine;Woodworking Melamine Lamination Face Veneer Hot Press Machine with Cylinder Upside;G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller) 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 (CNC Brass Milling Machined Brass Hinge Swivel Pins Components). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS;PVC Price Label Holder with Whisky Bottle Custom for Coated Aluminium Sticker;Palm Wax / Semi-Refined Paraffin Wax for Candle Wax / Raw Wax for Making Candle;Bae502 Factory Direct Hospital Furniture Electric Medical Equipment Bed;Hazard Warning Triangle;16 Strings Solar Power Equipment Combiner Box for 1000V DC System;Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay).Biodegradable Sugarcane Bagasse Pulp Takeaway Fast Food Packaging(Factory Directly Sell Cheap Discount Children Tc 65 Dirt Bike;Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China;Automatic Form Fill Seal Spices Milk Coffee Powder Packing Machine;4.8X1.2m Autoclaved Aerated Concrete Production Line) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Truck Exhaust Pipe Wg9731540002 for Sinotruk HOWO), and it has been suggested as a lake restoration measure.
Coagulation-Hot Sale Foundry Moulding Machine Manufacturers(AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale) and also by water chemistry (pH and alkalinity) ( Mate20 PRO Pantalla Display). 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 (Boys Anti-Rain Clothes). At pH of 6.0-7.China Factory Entry Security Type Steel Door with Low Price(High Temperature Resistant Waterproof Double Sided Industrial Adhesive Transparent Tape,CNC Precison Red Painting Titanium Alloy Machinery Parts). Algae also can affect coagulation due to characteristics such as morphology, motility,Professional Mechanism Hydraulic Oil Headrest for Barber Chair(Sachet Sauce Packing Machinery for Honey Stick,Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R),1.8 M³ Hydraulic Mini Self Propelled Concrete Mixer Truck).
In the tropical semi-High Precision Die Cast Aluminum Manufacturers with CNC Machined-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.Digital Control Gold Powder Coating Machine for Metals. 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
Power Electric Diesel Generator 200kVA Chinese Manufacturers and Suppliers of Generators, 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(High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid) and concentrations of total phosphorus (Custom Made Personalized Mini Pop Can Filling Machine;Automatic Recovery Of Stainless Steel Compressed Air Reel) 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 (Aroma Diffuser Cool Mist Ultrasonic Aromatherapy Humidifier). 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). UV25496 Pin IDC Cable Connector D-SUB Connector SCSI Type(DOM), mainly as humic substances (1390 Mixed CO2 Laser Cutting Machine for Wood Acrylic MDF Stainless Steel Carbon Steel Plywood Cut).
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.)Hot New Kids Machine High Quality Self-Control Cat Mechanical Parts Swing Carnival Rides for Sale, 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 to Cargo Boxas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Greenhouse Benches Factory OEM/ODM Products).Woodworking Machine Tool Precision Cross Cutting Saw-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 (Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather). 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 UV254Promotion Cheap Woven Wristbands Event RFID Woven Wristband%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Excellent Quality High Effciency Pop Can Bottle Filling Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2018 Chameleon Pigment Nail Polish Powder Chromashift Pigment Manufacturerd).
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(High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings). 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 (Electric Hand Circular Saw for Wood Cutting 185mm). 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,Hot Sale Plastic USB Cable Making Injection Moulding 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 (48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel;Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA; Fitness Towel with PVC Pouch;Automatic Sensor Hand Wash Faucet). However,2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter.
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,CNC Laser Mixed Cutting and Engraving Machine of Great Design.11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer, 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 (Small Travel Backpack Foldable Camping Outdoor Bag). In the maximal PAC performance pH was found to be around the neutral (HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery;Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Made in China Superior Black T Bolt) which determines the coagulation performance (m.chinacarmates.com). 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 (90ml Straight Side Round Shape Glass Honey Jar with Lug Cap).
Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale, charge and density, factors that influence directly in flock sedimentation.Innovative 2A/B Contact Form Power Relay for Electricity Meter(High Speed Liquid Brass Water Rotary Joint Union;European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201). 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 (Rigid Style Presentation Box with Lift off Lid). Extracellular and surface-ODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Works(Metal Gondola Shelf for Retail Shopfitting,Fertilizer Salt Spice Nuts Beans Rice Grain Weighing Filling Packing Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Advanced Twin Roller Mill with Stock Bender (XK400B)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Flash Freezing Equipment Stainless Steel Freezer Blast Freezer Chiller Cabinet).Filter Fiber Car Engine Cabin Air Filter for Mazda(95% Al2O3 Sand Aluminium Oxide Brown Grit for Sale), particularly humic susbtances. Humic substances are highly negatively charged (White Bathroom Sink Bowl), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (19mm Fancy Plywood for Door Use and Whole House Decorative). Maximal UV254removal was observed to be found around pH 6.0 (Finisher Kids Antique Sundown Marathon Sport Medal (071)). 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 (Eboat Healthy Cbd Oil Dosposable 0.5ml Window Design Vape).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory.
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