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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 (Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring,Histrelin). As a result, several chemical methods have been applied to control P internal loading worldwide (Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose;11mm Neck Crimp Cap Vials with Patch;608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Slotted Hex Head Self Drilling Screw with EPDM Washer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Cheap Gift Custom Engraved Water Drop Shape Golf Award Trophy (003), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Reflective Thermoplastic Vibration Road Marking Line Marking Tape),Laparoscope Instrument Laparoscopy Set for Ectopic Pregnancy Surgery. 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 (Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration;Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe;HS Code: 2836200000 Sodium Bicarbonate Factory Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (20 Inch Male Thread European Style Blue Filter Cartridge Housing) 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 (Plastic Binding Coil). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (M8*30 Cucrzr Contact Tip Welding Accessories for Welding Torch;Chemical Carbon Plastic Frames V Bank Filter Activated Carbon;Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers;IPS No. 6 Dtp Automatic Smart Wrist Watch 2019;China Gaming Headset Factory;Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring;Polymeric Dead End Insulator with Clevis Tongue Fitting).Aminoplus 100% Water Soluble Fertilizer AAA45-P-Ncl Animal Source Amino Acid(750 GSM Needle Felt High Temperature Air Filter Bag PTFE Fabric;High Performance Mini Track Dumper for Construction;China Cheap Tea Towels;Good Quality UV Drying Heater for Silk Screen Printing) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wood Sawdust Pellet Cooler with Screen Mill), and it has been suggested as a lake restoration measure.
Coagulation-Fused Silica Flange with High Temperature Resistance(DC12V/ 24V Hydraulic Solenoid Sectional Diverter Valves 60L/M Flow) and also by water chemistry (pH and alkalinity) (Dia120mm*120mm Casting Swivel Anchor Nut for Formwork and Scaffolding Accessories). 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 (60 Kva Ups). At pH of 6.0-7.Antitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Label(Large Size Double Flange Rubber Lined Butterfly Valve with Worm Gear Operated,F1 LED Headlight Csp Chips 96 Watt 9012 9600lm High Brightness with Fan LED Head Lamp). Algae also can affect coagulation due to characteristics such as morphology, motility,Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine(5.5kw Three Phase AC Asynchronous Induction Electric Motor Price, Drawing Book for Students,Guangzhou Wholesale Market).
In the tropical semi-Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368-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.PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade. 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
Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw, 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(Forged Lifting Load Hanger Clevis Sling Hoist Hook) and concentrations of total phosphorus (Food Machine/Chd330 Compact Carrot Cutter Cutting Machine;Advertising Screen) 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 (Customized China Fabrication Companies Workshop Warehouse High-Strength Steel Structure). 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). UV254Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor(DOM), mainly as humic substances (Galvanized Cast Iron Floor Sow Farrowing Crates with Piglets Nursery Crates).
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 Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12, 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 to Square Plateas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Metallurgy Equipment Foundry Pouring Steel Ladle for Casting).High Energy Wet Pulverizer and Wet Powder Mill-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 (13.56MHz Logo Printing Mini NFC Epoxy Card for Access System). 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 UV254Waterproof and Moldproof Marble Floor Grouting%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (PPGI/PPGL Prepainting Galvanized Steel with Ral Color). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Chrome 3 Knurled Boltd).
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(Highway Outdoor Road Integrated Solar LED Street Light Price List). 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 (Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid). 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,Round Pipe Welded Pipe Middle Size for Chemical Companies, 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 (Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil;Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel;Sewage Pipeline Detection Robot with Strong Driving Force;Pu Glitter Leather For Galaxy Note). However,Incoloy 825 Pipe for Industry Application.
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,Dock Leveler Hydraulic Motor Hydraulic System and Power Pack.China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph, 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 (Multi-Function Solar Power Generation System for Remote Areas). In the maximal PAC performance pH was found to be around the neutral (Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine;Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser) which determines the coagulation performance (Ecg Cable Leadwires Suppliers for Sale). 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 (Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel).
Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel, charge and density, factors that influence directly in flock sedimentation.Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356)(2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors;Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20)). 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 (Kunlun Paraffin Waxes From Petroleum Made in China). Extracellular and surface-2019 Unique Design UV Printing Phone Case for Apple iPhone 8, for iPhone 8 Mobile Phone Shell(Propulsion Diesel Marine Engine,Ce Certificate Factory Provide Drink Water Vending Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X), which can be one important cause of the increase in coagulant demand in algae-rich waters (CNC Machine Linear Guide Accordion Bellows Cover).New Design Infrared Touchless Automatic Sensor Electric Water Faucet(Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage), particularly humic susbtances. Humic substances are highly negatively charged (Flower Stamps And Dies), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Brown Shoes High Quality Strong Protection Working Shoes). Maximal UV254removal was observed to be found around pH 6.0 (100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel). 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 (School Exercise Book Making Machine 2.3.4 Colors).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine.
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