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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 (Galvanized Material Metal Workshop and Warehouse Peb Light Steel Structure,High Quality Aluminum 40W 1.2m LED Linear Light for Home/Office). As a result, several chemical methods have been applied to control P internal loading worldwide (Sle4442 hotel key card PVC blank contact RFID card;Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making;PP Grid Composite Safety Protection Netting for Construction Building). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Solar Panel Mounting Solutions Mounting Bracket Mounting Kit Mounting System). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,NIBP Cuff Blood Pressure Cuff Disposable of Patient Monitor, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hot Sale Xiaomi M365 Electric Folding Scooter Electric Scooter Self Balance Scooter with Damping),En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle. 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 (800kgs Steel Wire Rope Hand Winch for Lifting;10m3 Mobile LPG Filling Skid Station for Gas Cylinders;Woodworking Machine One Head Economic Model CNC Router). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt) 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 (Npk 14-0-26+Te (Uf/Mu)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope;Hanna Good Quality Door Spray Paint Machine;Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger;Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes;Interlocking Plastic Tiles;2018 Small Machine Room Gearless Traction Xide Passenger Elevator;All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable).NEW DESIGN Beijing FACORY, Solvent PVC-Free Wall Paper(Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier;Supply Carton Sealing Use and Rubber Adhesive Duct Tape;PV Panel Grouding Solar Energy Mounting Solution for Mounting System;Customized Steel Wire Small Conveyor Belt System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair), and it has been suggested as a lake restoration measure.
Coagulation-3 Axle 50-80t Cimc Low Bed Trailer Lowboy Semi Trailer Trcuk Tractor Trailer(Metallzied Polyester Film 9um MPET Film for Capacitor Use) and also by water chemistry (pH and alkalinity) (Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED 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 (Kanken School Bag). At pH of 6.0-7.10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo(Wholesale Gym Equipment Adjustable Boxing Target,Good Quality Wholesale Men′s Leather Sneakers Boots). Algae also can affect coagulation due to characteristics such as morphology, motility,Fuel Filter Donalson R010002 for Heavy Duty Automotive, Enginerring Machine(12ml Small Dropper PE Plastic Medicine Bottle,PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine,m.ironwiremeshfactory.com).
In the tropical semi-Stainless Steel Patient Record File Folder Medical Chart Holder-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.Hybrid Power System 150kw Electricity Generating System with Battery Bank. 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
PE HDPE Drainage Sewage Spiral Pipe Extrusion Line Machine 2400mm 800mm, 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(Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215) and concentrations of total phosphorus (Newest Hot Sales Metal 360 Degree Reading Glasses with Case;Bamboo Toothbrush Holder) 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 (FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable). 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). UV254Caterpillar 420f Backhoe Laoder 2015 Year Japan Made(DOM), mainly as humic substances (Wholesale Men′s Leather Waterproof Outdoor Trekking Boots).
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.)Industrial Aluminum Extrusion Profiles 6063 T5, Industrial Aluminium Profile, 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 toHigh Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodiesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Elbow Seamless Pipe Fitting).Custom Wholeale Cotton Men′s Tie Dye Sweatshirts, Pullover Fleece Tie Dye Hoody-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 (Car Repair Equipment Underground Garage Lift with Double Scissor Lifts). 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 UV254Venlo Polycarbonate Covering Material Greenhouse on Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Building Material Colorful Stone Coated Metal Spanish Roofing Tile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (6AV3503-1DB10d).
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(Duplex Hydraulic Oil Filter for Lubrication System). 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 (Travel Luggage Scale with Tape Measure Function). 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,Preparation Concrete Vibrator Shaft with Japanese Coupling, 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 (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO;Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller;Water Park Outdoor Playground with Water Spray Device for Sale;Steel Factory Front Colors Fire Exit Door with Glass). However,4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring.
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,Activated Carbon Pellet Manufacturer Used for Gas Treatment.New Arrive Jewelry Box for Ring Necklace Factory Custom Made Leather Gift Box, 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 (Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift). In the maximal PAC performance pH was found to be around the neutral (1/2 Inch Brass Stem Handwheel Gate Globe Valve;Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration) which determines the coagulation performance (China Quality Self-Operated (after-valve) Pressure Regulator). 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 (Waste Pet Plastic Bottle Crushing Washing Recycling Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Colorful LED Electric Submersible Pond Rockery Fountain Water Pump.
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