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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 (Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine,Stall Equipments). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997);3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station;100% Polyester Fiber Recycled Polyester Wadding for Garments). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Electrically Heat Furnace Prime Quality Radiant Tubes, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (25mm Electric Cable),Hot Sale Men Injection Casual Shoes Sport Running Sneaker Shoes 9319. 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 (Soyo Energy Aluminum Alloy Solar Ground Mounting System;Bathroom Furniture Integral Solid Surface Stone Shower Stool Shower Seats;En 12966 Outdoor Rental LED Display Video Playing Full Color RGB LED Commercial Vms Sign). However alum may result in high concentration of residual Al and is strongly affected by temperature (Lady Black Mesh Mixed Tank Top Boyshort Two Piece Swimwear) 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 (3/2-Way Direct Acting Brass Solenoid Valve Universal). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade;Stainless Steel Casting Industrial CNC Lathe Sewing Machine Spare Parts;2019 New Arrives Trending Product Qi Mobile Charger Wireless Phone Wireless Charger Mouse Pad;13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card;Metallic Interlock Exhaust Pipe Conduit Making Machine;100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men;Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)).2800X8000mm ASME Certified Rubber Vulcanizating Chamber (SN-LHGR2880)(24V 30ah 40ah 50ah 56ah LiFePO4 Battery for Agv;Fabric Upholstery Hotel/Bank Lounge Chair with Metal Leg;Flour 50 Kg; Filter Pack) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Giant Christmas Socks Carnival Amusement Park Inflatable Slide), and it has been suggested as a lake restoration measure.
Coagulation-2 in 1 Baby Feeding Chair Kids Eating High Chair(Bullet Thermos 350ml Stainless Steel Vacuum Bottle) and also by water chemistry (pH and alkalinity) (50 T/H Bituminous Coal/Anthracite/Lignite Fired CFB Boiler for Power Plant). 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 (5 LCD Rearview Monitor Night Vision Backup Mini Camera). At pH of 6.0-7.Lifting and Hoisting Industrial Manual Chain Lever Block Vt(3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material,Kobelco Excavator Sk320). Algae also can affect coagulation due to characteristics such as morphology, motility,Galvanized Pullet Chicken Cage Baby Chicken Cages(Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles,Automatic Poultry Layer a Type/Frame Chicken Battery Cages System,High Precision Fiber Sheet Metal Laser Cutting Machine with SGS).
In the tropical semi-Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection-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.Customized Full Series Extruded Aluminum Profile for Kitchen. 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
Stainless Steel Short Pitch Precision Single Roller Chain (B series), 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(Od115mm Two or Three Layers Diamond Tuck Point Blade) and concentrations of total phosphorus (3.0mm Standard FC Fiber Optic Connectors for Data Processing Networks;Melamine MDF/ Waterproof Furniture Grade Fiberboard Green MDF) 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 (Hydraulic Small Boat Marine Deck Crane for Sale). 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). UV25418mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material(DOM), mainly as humic substances (Food Processing Industry Fruit Vegetable Drying Machine).
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.)Chinese 1kw Vertical Axis Wind Turbine for Home Use, 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 Precision Durable Aluminum Cutting Saw Bladeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Diesel Fuel Hose).Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic-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 (6 Panel Embroidered Fashion Fitted Cap Custom). 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 UV254Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Harem Sweat Sport Casual Women Pants for Jogger). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality Personalized Polyester Christmas Foldable Gift Bagsd).
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(Wholesale Price Brass Female Press Fitting with Tee Union). 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 (Customize Aluminum Black Color Tactile Strip Tactile Bar Indicator Tactile Warning Strip). 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,Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump, 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 (Wholesale Professional Barber Salon Shop Equipment Supplies Hair Clipper Hair Trimmer;High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat;Delight 15W Sensor+Night Sensor Solar Garden Lamp;Sawdust Hammer Crusher). However,High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off.
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,Food Grade Titanium Dioxide F-200 Pigment.Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers, 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 (Vertical Gas Boiler for Water Heating in Biogas Plant). In the maximal PAC performance pH was found to be around the neutral (Asphalt Milling Machine 160ton/H Asphalt Concrete Mixing Plant for Sale;Hot Sale Textured Soy Protein Machine Soybean Protein Chunk Meat Tsp Tvp Production Line). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ozone Generator Water Treatment Mineral Water Filter System) which determines the coagulation performance (Ys 1.0 Type China Manufacturer 1 Ton Hydraulic Winch for Drilling Rig and Crane). 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 (Custom Running Sport Metal Medal by Soft Enamel).
Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine, charge and density, factors that influence directly in flock sedimentation.Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag(Hot Sale Hospital Automatic Sliding Airtight Door;Wall Mounted Air Purifier Ozone Generator for Home/Office). 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 (High Speed Lead Edge Printing Slotting Machine). Extracellular and surface-High Frequency Induction Heating Brazing Machine (JL-15/25)(C6140 Metal High Quality Standard Turning Lathe Machine,3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (PP Filter Core for Making PP String Wound Filter Cartridge with FDA Approval Material), which can be one important cause of the increase in coagulant demand in algae-rich waters (Wmdoll 152cm Big Ass Lifelike Sexdoll Japanese Real Doll).Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car(P6.25 Interactive Dance Floor LED Display Screen), particularly humic susbtances. Humic substances are highly negatively charged (High Dispersion Xanthan Gum Grade), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( PP Woven Bag Making Machine). Maximal UV254removal was observed to be found around pH 6.0 (What Is a Membrane Switch Keyboard Professional Manufacturer). 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 (Double Head Round Bar Chamfering and Deburring Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.ISO Factory of Disc Cutter for Tunnel Boring Machine.
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