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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 White Cardboard Paper Roll to Sheet Cutting Machine,Stainless Steel Grinder). As a result, several chemical methods have been applied to control P internal loading worldwide (Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory;3mm Poplar Plywood with Fancy Veneer Directly;Farm Seed Spreader / Tractor Fertilizer Spreader for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Industry Basket Washing Machine Crate Washer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,F1 LED Headlight Csp Chips 96 Watt 9012 9600lm High Brightness with Fan LED Head Lamp, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Jiuhong Brand Rotatable Hemostatic Clip 11mm 13mm),3.0mm Standard FC Fiber Optic Connectors for Data Processing Networks. 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 (Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6;Steel Jacket Steam Insulation Pipe for High Tempertature Heating;6.2mmx6.2mmx4.3mm SMD Waterproof Tact Switch). However alum may result in high concentration of residual Al and is strongly affected by temperature (PP Yarn Water Filter Cartridge for Large Flow Rate) 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 (24 Hours Mechanical Timer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2019 New Products Wall-Mounted Household Natural Gas Alarm Low Power;Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould;High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge;Hot Sale 1: 1 High Quality Same Sound Effect Bluetooth Earphone Airpods for Apple iPhone;PE HDPE Silicon Core Cable Duct Plastic Pipe Extruder Machinery; 42′ LG LED TV Backlight Lens Strips/Bars/Spears; Drying Equipment).Car Parts Thermostat Housing with 4-Pin Sensor for Renault(Customized Acrylic Plastic Sign Board Design Customized Size;Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003);m.nsen-valve.com;Chinese 1kw Vertical Axis Wind Turbine for Home Use) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2.45 2.45. inch OLED display 304X96 DOT Matrix MONO OLED), and it has been suggested as a lake restoration measure.
Coagulation-14G Auto Computerized Collar Flat Knitting Machine( Temperature Controller Thermostat 110V for Cabinet Use) and also by water chemistry (pH and alkalinity) (11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer). 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 (www.excaliburgenerator.com). At pH of 6.0-7.Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5)(Customized Epoxy Plated Super Power Neodymium Magnet Bonded Magnetic,High Quality Precision Aluminum Automatic Lathe CNC Machining Parts). Algae also can affect coagulation due to characteristics such as morphology, motility,90ml Straight Side Round Shape Glass Honey Jar with Lug Cap(200m Deep Top Driving Tractor Mounted Water Well Drill Equipment,20FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container,Electrical 4 Pin Yazaki Automotive Connecor).
In the tropical semi-130kg/M3 Plastic PVC Core Foam for FRP Vacuum Infusion-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.Washroom Systems Wc Changing Wet Room Ensuite Shower Room Cubicles Prices. 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
Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting, 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(304/304L 316/316L Seamless Stainless Steel Pipe for Heat Exchanger) and concentrations of total phosphorus (Wooden Grain Siding Plank for Villa Integrated House;25kg Per Bag PAM Cationic Chemical Catalysts Auxiliary Agents Polyacrylamide) 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 (55kw 65kw Industrial Air Cooled Water Chiller Unit). 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). UV254Women′s Ladies Simple Casual Leather Strap Quartz Wris Watch 71355(DOM), mainly as humic substances (Wired/Wireless Smoke Detector for Fire Alarm Home Alarm System).
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.)Ouwave HVAC Scent Fragrance Systems Aroma Diffuser Electric Scent Machine, 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 toRubber Wheel Stopper Car Parking Blocks Rubber Speed Cushionas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Printed Barbell Grips Silicone Hand Grip Rubber Protective Covers).Interlocking Foam XPE Gym Mats in Martial Arts-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 Precision Ultrasonic Vibro Screen for Refractory Material Separating). 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 UV254Mt-5113s Digital Textile Sublimation Inkjet Printer Solvent Printer for Transfer Paper Wood%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (16mm Rotary Potentiometer with Switch for Audio Equipment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Adult Sex Toy Anal Realistic Male Love Sex Dolld).
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(Hydraulic Cargo Freight Platform Lift for Industrial and Wearhouse). 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 (Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller). 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,Absorbent PP Mat Hardwearing Doormat with Round Shape, 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 (Y32f-112lm8 Small and Light PCB Relays with High Power for Comunication Equipment; Door Mat;Made in China Multi-Storey Steel Structure with Light Steel Frame;ISO9001 Black Rubber Tubing Braided Hose Fuel Oil Delivery Hose Farm Hose Pipe). However,New Business Projects Mobile 5D Cinema with High Quality.
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,Zumex Style Speed Tank Podium Commercial Citrus Juicer.High Quality Galvanized Pan Head Self Drilling Screw, 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 (Easy-to-Use School Office Invisible Stationery Tape). In the maximal PAC performance pH was found to be around the neutral (Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor;4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Cold Storage Warehouse Rack with Good Quality) which determines the coagulation performance (Wholesale 2018 Canvas Mens College Student Shoulder Bag). 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 (Brc Welded Wire Mesh Fence/3D Curvy Welded Wire Mesh Fence).
Bct-01 Hospital Furniture ABS Medical Emergency Treatment Trolley Cart, charge and density, factors that influence directly in flock sedimentation.Co-Extrusion Extruder Single Screw Auxiliary(A4;High Efficiency Hook Type Shot Blasting Machine 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 (Non-Toxic RTV Silicone Sealant of Full Automatic Machine). Extracellular and surface-5 (125mm) /8 (200mm) Ce Double-Wall Stainless Steel Stove Pipe for Chimney Pipe(Car Toys For Kids Drive,High Tensile Forged Chain with Conveyor for Conveying System). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (M5 SMD with Internal Blind-Hole Thread with Pin (groove)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile).Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks(Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed), particularly humic susbtances. Humic substances are highly negatively charged (Generator Power Station Supplier), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Customized Wire Mesh for Decorative Garden Fence). Maximal UV254removal was observed to be found around pH 6.0 (Fan Cooling Oval Design Commercial Cake Display Showcase Fridge). 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 (China Qingdao Factory Interlocking PVC Garage Floor).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Brass Screen Mesh Brass Wire Mesh Brass Mesh Cloth.
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