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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 (Woodworking Machine One Head Economic Model CNC Router,Led Growth Light). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt;100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope;Hanna Good Quality Door Spray Paint Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,New Product 2019 Milky White Electrochromic Smart Film, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Quality 110V DC Power Supply with US Plug),Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp. 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 (Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes;2018 Small Machine Room Gearless Traction Xide Passenger Elevator;All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable). However alum may result in high concentration of residual Al and is strongly affected by temperature (Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier) 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 (Industrial Meat and Bone Waste Meal Cooker Machine for Manufacture). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Supply Carton Sealing Use and Rubber Adhesive Duct Tape;Customized Steel Wire Small Conveyor Belt System;Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair;Metallzied Polyester Film 9um MPET Film for Capacitor Use;Wood Texture Melamine MDF Board for Furniture Cabinets;Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display;Wholesale Gym Equipment Adjustable Boxing Target).Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047)(Good Quality Wholesale Men′s Leather Sneakers Boots;12ml Small Dropper PE Plastic Medicine Bottle;Wholesale Virgin Material PP Woven 50kg Sugar Bags and Sacks;PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Middle Duty 20 Discs Harrow for 50 HP Tractor), and it has been suggested as a lake restoration measure.
Coagulation-Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor(Hot and Cold Temperature Thermal Shock Testing Equipment) and also by water chemistry (pH and alkalinity) (Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215). 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 (Industrial Biogas Generator). At pH of 6.0-7.Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X(Newest Hot Sales Metal 360 Degree Reading Glasses with Case,Hydraulic Press Machine Deep Drawing Press 100 Ton). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate(Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder,FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable,Customized Alloy and Cast Iron of Brake Drum as Drawing).
In the tropical semi-Living Room Furniture TV Stand Electric Fireplace with No Heating-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.High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings. 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
15 Inch IP65 Waterproof Industrial Touch Screen Monitor, 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(Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004)) and concentrations of total phosphorus (PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable;Ceramic Heater) 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 (Forging SAE4140 S31803 Steel Crusher Eccentric Shaft). 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). UV254Steel Warehouse Metallic Curved Roof Design Structure(DOM), mainly as humic substances (Car Repair Equipment Underground Garage Lift with Double Scissor Lifts).
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.)High Precision Customized Medical Injection Mold for Needle Holder, 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 toTravel Luggage Scale with Tape Measure Functionas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Brass Flat Countersunk Head Slotted Machine Screw #2-56 4-40 6-32 8-32 10-24 12-24 M2 M3 M4 M5 M6).Remote Lighting Controls Outside Lights Controller LC-6p13-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 (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO). 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 UV254Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (35 Gallon Fish Tankd).
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(Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift). 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 (1/2 Inch Brass Stem Handwheel Gate Globe Valve). 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,1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar, 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 (Waste Pet Plastic Bottle Crushing Washing Recycling Machine;Glass Mike Bottle 200ml 250ml with Screw Cap Straws;Liquid Laundry Detergent Small Single Bag Packing Machinery;Cold Room Storage Refrigeration Equipment for Supermarket). However,Hjd-J3 Double-Position Semi-Automatic Heat Transfer 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,Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine.Reusable Side Gusset Eco Zip Lock Bag Supplier From China, 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 (2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part). In the maximal PAC performance pH was found to be around the neutral (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug;Semi-Automatic Hydraulic Leather Football Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (15 Inch IP65 Waterproof Industrial Touch Screen Monitor) which determines the coagulation performance (1 Inch Cover Oil Hose). 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 (Modern Style Prefabricated Steel Structure Poultry House).
Easy Maintenance Automatic 6000PCS/H Egg Tray Machine, charge and density, factors that influence directly in flock sedimentation.Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material( Splicing Machine S6;Double Deck High Quality Aluminum Pontoon Boat for Sale). 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 (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)). Extracellular and surface-Korea Glittery Heat Transfer Film /Vinyl for Clothes/T-Shirt Printing Cdg-16 Light Multi(Dj Light Shop,Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Floor Mounted Glass U Clamp Channel for Glass Balustrade), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Quality Curve Spear Tunnel Bolt for Concrete Ring).Glossy Silvery Anodized Aluminium Profile for Windows and Doors(Brand New Forklift with Double Front pneumatic Tire), particularly humic susbtances. Humic substances are highly negatively charged (Active Rfid Readers), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Automatic Small Round Bottle Water Washing Filling Capping Machine). Maximal UV254removal was observed to be found around pH 6.0 (MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). 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 (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Shoebox Canopy Lamp 60W LED Light Evergy Saving 2835 Chips Corn Bulb.
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