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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 (Luxury Goose Duck Down Feather Filling Pillow for Hotel Home,Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven). As a result, several chemical methods have been applied to control P internal loading worldwide (China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3;Durable Rectangular FRP Pultruded Grating for Glassfiber Platform;2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Travel Wallet RFID Blocking Document Organizer Bag),New Mini Loader Radlader Mini Zl936 Wheel Loader. 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 (Eco-Friendly Euro Plastic Container with Lid;Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector;FDA Approval Professional Skin Rejuvenation Shr IPL Hair Removal Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Soft Galvanized Steel Coil/Strip Gi/Gl for PPGI PPGL0.13) 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 CNC Metal Cutting Machine / Machines with Huayuan 200A). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Disposable Double Ended Cleaning Brushes for Endoscope Port Hole;Reusable Side Gusset Eco Zip Lock Bag Supplier From China;1W Colorful Garden Park Plaza Lawn Underground Lamp;High Speed Precision CNC Fiber Laser Marking Machine;JEKEEN Customized BBQ Trailer with Various Cooking Pot of Barbie;Vacuum Dryer Machine China Supplier with High Frequency Technology;All in One Cabinet Fruit and Vegetable Dryer Middle Temperature Food Dehydrator).Fein Titanium Bi-Metal Oscillating Saw Blade(Auto Electrical Heater Blower Motor for Benz 2208203142;Enuo DIN En 853 856 Flexible Oil Rubber High Pressure Hose;Glass Door Upright Stainless Steel Freezer Commerical Upright Chiller;Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Cafe Furniture Rectangular Dining Table), and it has been suggested as a lake restoration measure.
Coagulation-Diesel Engine Parts Cylinder Head for Mitsubishi 4D30A/4D31 Me999863(2019 China Professional PE/PP Knotless Net Extrusion Line Machine) and also by water chemistry (pH and alkalinity) (Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair). 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 (Poly Aluminium Chloride PAC 30% Polyaluminium Chloride for Water Treatment). At pH of 6.0-7.FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound(Tube Polished Heat Resistant Al2O3 Alumina Zro2 Zirconia Ceramic Pipe,BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle). Algae also can affect coagulation due to characteristics such as morphology, motility,Handrail Fitting / Stainless Steel Round & Square Tube Connector(Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock,Zinc Alloy 103 Mailbox Post Tubular Drawer Cabinet Cam Lock,Portable AC Power Bank 12V Car Jump Starter).
In the tropical semi-Mobile Fast Food Vending Hot Dog Concession Trailer/Cart Pizza Truck/Mobile Food Car-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.BRT Gasoline Log Splitter 22 Ton Firewood Processor. 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
Android Data Cable Mobile Phone USB Cable Mobile Phone Cables, 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(China Supplier PPGI Coils for Construction Materials) and concentrations of total phosphorus (HOWO 8X4 Aluminum Alloy 35000L Gasoline/Oil/Fuel Tanker Truck;Aluminum/Brass/Steel CNC Small Batch Machining Machine Parts) 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 (Panasonic Ai Spare Parts X004075 with Large Stock). 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). UV254Rubber Product Making Machinery / Car Floor Mat Hydraulic Vulcanizing Press(DOM), mainly as humic substances (Ceramic Components Applied in Machinery Industry).
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.)Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook, 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 toCustomized EPDM NBR Rubber Bellows Expansion Jointas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cylindrical Pressure Spring of Carbon Steel).Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter-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 (High Axial Flow Clean Water Submersible Sump Irrigation Pump). 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 UV254Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Air Bubble Stone as Ozone Diffuser for Air Pump). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Jacquard Carpetd).
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 Plastic HDPE Foldable Rectangle Folding Wedding Tables). 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 (Rigid 94V-0 PCB Fr4 Double-Sided PCB with 1.6mm Thickness 2 Layer). 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,Transparent High Quality Building Glass Curtain Wall From China Suppliers, 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 (Simple 3 Fold Orthopedic Folding Foam Mattress;Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;Factory Price Resin Wedding Chairs for Sale;China Store Display Rack Angle Steel Slotted Boltless Rivet Shelving). However,Professional Produce Dmp-430A Vacuum Tray Sealer.
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,Cation Printing Effect Micro Fleece, Jacket Fabric (nautical blue).Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique, 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 (Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm). In the maximal PAC performance pH was found to be around the neutral (Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic;Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings) which determines the coagulation performance (Durable Copper Tubular). 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 (Round Pipe Welded Pipe Middle Size for Chemical Companies).
Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace, charge and density, factors that influence directly in flock sedimentation.Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage(Quality Medium Stapler with Staples Remover;G02f12L Tempered Glass Shower Cabin). 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 (Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel). Extracellular and surface-Construction Equipment Full Automatic Concrete Block Making Machine(Sheen Nk Prebuilt Coils,Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( 7050), which can be one important cause of the increase in coagulant demand in algae-rich waters (115cm Mini Sex Doll for Man Big Breast Love Doll).Customized Sheet Metal Products, Stamping Parts, Welding Parts(Fancy Design Formal Dress Shirt Short Sleeve for Women), particularly humic susbtances. Humic substances are highly negatively charged (Final Drive Assy With Travel Motor), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Pear or Regular Shaped Screw Lock Metal Quick Link). Maximal UV254removal was observed to be found around pH 6.0 (Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs). 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 (Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cartoon Design Decorative PVC Sheet for Wall Panel Moulding.
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