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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 (Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt,2019 China Industry Production Automatic Liquid Paint Spraying Booth Use New Technology). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Chain Rigging Clip U Bolt Saddle Cable Clamp, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Low Carbon Steel Pipe),PA Nylon Black Flexible Corrugated Pipe for Machine Fire Resistant. 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 (2018 Small Machine Room Gearless Traction Xide Passenger Elevator;All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable;Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier). However alum may result in high concentration of residual Al and is strongly affected by temperature (Supply Carton Sealing Use and Rubber Adhesive Duct Tape) 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 (m.reclining.cn). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display;Comfortable Durable Cotton Large Pet Car Seat Cover with Pokets;Wholesale Gym Equipment Adjustable Boxing Target;Good Quality Wholesale Men′s Leather Sneakers Boots).Supply Carton Sealing Use and Rubber Adhesive Duct Tape(12ml Small Dropper PE Plastic Medicine Bottle;PVC Edge Banding Printing Machine Tape Banding Machine Wire Banding Machine;Contact Spring;Middle Duty 20 Discs Harrow for 50 HP Tractor) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot and Cold Temperature Thermal Shock Testing Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen(Students Bags School Backpack Childrens′ Shoulder Bag Yf-Sbz2215) and also by water chemistry (pH and alkalinity) (Newest Hot Sales Metal 360 Degree Reading Glasses with Case). 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 (Led Panel Lights). At pH of 6.0-7.Electrical Wire Harness with Thermal Fuse(Hydraulic Press Machine Deep Drawing Press 100 Ton,Screw Type Hot Feed Cold Feed Rubber Extruder Rubber Machine Extruder). Algae also can affect coagulation due to characteristics such as morphology, motility,Stainless Steel Plate Frame Customized Sheet Metal Processing Laser Cutting(FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable,Wholesale Men′s Leather Waterproof Outdoor Trekking Boots,Lever/Gear/Electric Actuator/Pneumatic Actuator Ball Valve).
In the tropical semi-Expert Supplier Of Stainless Steel Electric Cooking Pot-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.Industrial 128X64 Cog LCD 28 Pin TFT White LED Transflective MP4 Mono LCD Display Screen Module. 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
Personalized Heat Transfer Printing Plastic Ice Bucket Beer Champagne Cooler, 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(PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable) and concentrations of total phosphorus (High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies;Factory Sale MIG Welding Gas with Mapp PRO Propane Gas) 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 (Car Repair Equipment Underground Garage Lift with Double Scissor Lifts). 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). UV254Shenzhen Manufactory Specilized in LED Light Manufacturing Line Setup(DOM), mainly as humic substances (Building Material Colorful Stone Coated Metal Spanish Roofing Tile).
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.)JAC 4X2 3ton 5ton Refrigeration Truck Freezer Box Truck, 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 toCommercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110Vas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Folding Beach Table).Food Packaging Laminated Roll Film for Food Packaging-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 (Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller). 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 UV254Customized Microfiber Sport Towel for Swimming Towel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Water Park Outdoor Playground with Water Spray Device for Sale). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Kids Indoor Trampoline Bedd).
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(1/2 Inch Brass Stem Handwheel Gate Globe Valve). 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 (Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer). 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,Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light, 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 (Glass Mike Bottle 200ml 250ml with Screw Cap Straws;Liquid Laundry Detergent Small Single Bag Packing Machinery;2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part;Working Mode Factory Supplier Solar Street Lamp 60W Integrated LED Lighting). However,Removable Tissue Cutting Machine (double channels).
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,Steel Jacket Steam Insulation Pipe for High Tempertature Heating.High Speed Four Shafts Auto Exchange BOPP Tape Cutting Machine, 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 (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug). In the maximal PAC performance pH was found to be around the neutral (Semi-Automatic Hydraulic Leather Football Machine;15 Inch IP65 Waterproof Industrial Touch Screen Monitor). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Modern Style Prefabricated Steel Structure Poultry House) which determines the coagulation performance (Shenzhen Supplier Vape E-Cigarette Kits 400mAh Cbd and Wax Vape). 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 ( Splicing Machine S6).
Washroom Water Tap of Hot and Cold Water Mixer, charge and density, factors that influence directly in flock sedimentation.Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light(Double Deck High Quality Aluminum Pontoon Boat for Sale;Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)). 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 (Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes). Extracellular and surface-Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine(100w Ufo Led Highbay Light High Quality Supplier,Floor Mounted Glass U Clamp Channel for Glass Balustrade). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Quality Curve Spear Tunnel Bolt for Concrete Ring), which can be one important cause of the increase in coagulant demand in algae-rich waters (Brand New Forklift with Double Front pneumatic Tire).PPGI Sheet Price From China/Pattern Designed Wooden PPGI Shandong Manufacturer(Automatic Small Round Bottle Water Washing Filling Capping Machine), particularly humic susbtances. Humic substances are highly negatively charged (Linear Machine for Producing Sole), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). Maximal UV254removal was observed to be found around pH 6.0 (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor). 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 (Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Long Span Galvanized Light Weight Steel Structure.
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