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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 (Stainless Steel Black Matt Kitchen Faucet,Plastic Binding Coil). As a result, several chemical methods have been applied to control P internal loading worldwide (Auditorium Chairs for Public Furnitures;2018 Newest Camping Hiking Bug Net Hammock;UL Ce LED Bullet Floodlight Lighting Fixture). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Gear Box Forged Steel Bw Ends Full Welded Ball Valve, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Gaming Headset Factory),Engineering Plastic Material, Nylon/PA Sheet. 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 (Shiny Bamboo Joint Polyester Stretch Satin Fabric;New High Cube Grain Loading 20FT Intermediate Dry Bulk Container;Fast Speed Packing Machine Small Candy Packaging Machinery Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (RO Water Treatment Plant Water Purifying System Water Filter Machine) 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 (China Cheap Tea Towels). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Multi-Viewing Biological Microscope with Good Price;Chc-B07 Health Stainless Steel Germanium Bracelet for Female;Best Quality Plastic Access Panels Ap7611;HEPA Air Purifier with Photocatalyst;60 Kva Ups;BPA Free 100% Food Grade Silicone Baby Pacifier;Aluminum 6061 CNC Precision Custom Machining Part CNC Turning Brake).Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging(ERW Welding Black Steel Tube for Construction/ Structure / Building;One-Stop Condensing/Compressor/Refrigeration Unit Freezer Cold Store;Guangzhou Wholesale Market;Full Automatic Chocolate Holding Tank with Water Jacket) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy), and it has been suggested as a lake restoration measure.
Coagulation-Heated Lunch Box/ Food Insulation Plastic Box/Heat Preservation Plastic Box(Water Centrifugal Pump for Swimming Pool Water Transfering) and also by water chemistry (pH and alkalinity) (Water Jet Cutting Machine Spare Parts Waterjet 3/8 High Pressure Pipe). 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 (Advertising Screen). At pH of 6.0-7.Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile(PPGI Sheet Price From China/Pattern Designed Wooden PPGI Shandong Manufacturer,Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt). Algae also can affect coagulation due to characteristics such as morphology, motility,500ml Amber Pharmaceutical Glass Bottle Medicine Bottle Chemical Bottle Pesticide Bottle(Vci PE Film for Ferrous Metal with Anti-Rust Performance,Hot Sale Pig Farm Equipment Galvanized Farrowing Pens,Commercial Fully Automatic Car Wash Equipment From Royalstar Brand China).
In the tropical semi-Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile-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.18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless. 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
5FT2′ 157cm Female Premium Platinum Silicone Love Doll Lifelike Adult Love Sex Toy for Men, 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(Marine PVC Lining Durable Fire Hose Double Jacket Fire Hose) and concentrations of total phosphorus (Magic Smart Bluetooth Illuminated Mirror Bathroom LED Mirror with Clock Display;Metallurgy Equipment Foundry Pouring Steel Ladle for Casting) 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 (Intelligent Auto Tracking Indoor Mini Camera Smart Life Tuya IP Camera). 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). UV254Hot Selling Waterproof Anti-Slip Vinyl PVC Homogeneous Plastic Roll Floor(DOM), mainly as humic substances (Stormwater Retain Dimple Plastic Board Roll Drainage Sheet).
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.)Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration, 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 to240L German High Capacity Shopping Trolley with Baby Seatas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Sport Shoes Middle Sole in EVA Making Machine).Edo Cute Kids Cartoon Waterproof Picnic Lunch Food Wine Insulated Durable Tote Storage Cooler Bag-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 (Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion). 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 UV254Industrial and Commercial Screw Compressor Water Chiller%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Strong and Durable Outdoor Wedding Furniture Resin Solid Wood Wimbledon Folding Chair). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pu Glitter Leather For Galaxy Noted).
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(OEM Design 24 & 30 Cavities Cold Runner Spoon Mould). 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 (100% Cotton Heavy Duty Workwear Wholesale Work Clothes). 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,Outdoor Self Adhesive Reflective Vinyl Plastic Sheet Traffic Tape, 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 (24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp;Portable Silicone Food Fresh-Keeping Kitchen Storage Freezer Bag;Drainage Rubber Grasss Ground Stabilisation and Play Area Anti Slip Rubber Mat;Propulsion Diesel Marine Engine). However,Automatic Vacuum Packing Premade Tray Filling&Sealing Machine.
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,XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet.220kv Composite Suspension Insulators for Transmission and Distribution Line, 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 (Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood). In the maximal PAC performance pH was found to be around the neutral (High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing;IP65 Waterproof Metal Distribution Box and Power Metal Box). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable) which determines the coagulation performance (Flower Stamps And Dies). 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 (Masturbators Adult Sex Toys Japanese Love Doll).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Runner High Precision Plastic Injection Mold for Household Home Appliance.
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