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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 (Manhole Cover Stainless Manway Tank Hatch Cover,Ce Respirator). As a result, several chemical methods have been applied to control P internal loading worldwide (Compostable White Take Away Disposable Paper Lunch Box;Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats;Factory Direct Seal Y14f General Power Relay 5 Pins). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,KERONG Electronic Keypad Digital Combination Hardware Glass Locks For Lockers′ Safes, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (WPC machine),Private Label Washing Laundry Powder Detergent. 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 (Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks;Flexible Cloth Backdrop P18 3X6m LED Video Curtain;1oz Square Glass Storage Mason Jar with Cork Lid). However alum may result in high concentration of residual Al and is strongly affected by temperature (2016 500W Razor Crazy Electric Drift Trike for Adult) 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 (High Power Lighting System Solar Street Lights Solar LED Power). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Low Cost Commercial Plastic Film Greenhouse for Sale;Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring;Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose;11mm Neck Crimp Cap Vials with Patch;200ton Jh25 Series Double Crank Sheet Metal Stamping Press;608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing;Slotted Hex Head Self Drilling Screw with EPDM Washer).Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank(Compact Swimming Pool Filter/ Complete Set Swimming Pool Filtration;Inlet Pipe for 93-02 Toyota Supra 2jz Ge Down Pipe Downpipe;High Energy Efficiency Double Door Showcase for Supermarket;HS Code: 2836200000 Sodium Bicarbonate Factory Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (20 Inch Male Thread European Style Blue Filter Cartridge Housing), and it has been suggested as a lake restoration measure.
Coagulation-Ce Approved Gobal Warranty 200kVA 100kVA 50kVA 25kVA Diesel Generator Price(M8*30 Cucrzr Contact Tip Welding Accessories for Welding Torch) and also by water chemistry (pH and alkalinity) (Chemical Carbon Plastic Frames V Bank Filter Activated Carbon). 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.kseidon.com). At pH of 6.0-7.Yhzs50 Mobile Concrete Mixing/Batching Plant with Low Price(Women&Men Dark Blue Color Closed Toe Waffle SPA Slippers,IPS No. 6 Dtp Automatic Smart Wrist Watch 2019). Algae also can affect coagulation due to characteristics such as morphology, motility,Fast Food Catering Airstream Trailers or Mobile Electric Airstream Food Truck Food Caravan Cart(Oil Resistance Fluoro Rubber Viton Oil Seal FKM Rubber Ring,Polymeric Dead End Insulator with Clevis Tongue Fitting,Electro Scooter).
In the tropical semi-Wholesale Bedding Set Hotel 100% Cotton Bed Sheets White-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.3 PCS Set Round Microwable Borosilicate Glass Food Container with PE Lid Vacuum Glass Bento. 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
Long Range UHF RFID Animal Ear Tag for Animal Management, 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(Good Quality UV Drying Heater for Silk Screen Printing) and concentrations of total phosphorus (Wood Sawdust Pellet Cooler with Screen Mill;fastlinepcb) 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 (Large Size Double Flange Rubber Lined Butterfly Valve with Worm Gear Operated). 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). UV254CNC Router 2030 3D CNC Foam Rubber Gaskets Oscillating Knife Leather Cutting Machine(DOM), mainly as humic substances (F1 LED Headlight Csp Chips 96 Watt 9012 9600lm High Brightness with Fan LED Head Lamp).
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.)Agriculture Machinery Belt Banded Cogged V-Belt, 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 toLow Cost Certificated Quality Aluminum Sheet 5083 Alloyas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Kids Winter Hoodies).10-100ml Paste Filling Packing Machine for Soy Sauce, Sauces-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 (Hot Sale Farm Implement 1bzd Series Tractor Mounted Hydraulic Opposed Hydraulic Disc Harrow). 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 UV254Two Pieces Ss Manual Ball Valve with Female Threaded Connection%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Industrial 128X64 Cog LCD 28 Pin TFT White LED Transflective MP4 Mono LCD Display Screen Module). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.arabellaclothing.comd).
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(Galvanized Cast Iron Floor Sow Farrowing Crates with Piglets Nursery Crates). 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 (Carbon Steel Zinc Countersunk/ Flat Head Self Tapping Screw). 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,3m 467MP Strong Adhesive Double Sided Transfer Tape, 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 ( Square Plate; Muffin Pastry Box;Silver Reflective One Way Vision Film as Mirror Performance (SF101);Interactive Led Floor Tile). However,Movable Oxygen Concentrator of Making High Purity O2 Gas Instead of Psa System.
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,Urea Cover U Shape Electric Heated Smart Toilet Bidet Seat.Great Quality Waste Water Treatment Polyaluminium Chloride PAC, 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 (13.56MHz Logo Printing Mini NFC Epoxy Card for Access System). In the maximal PAC performance pH was found to be around the neutral (PPGI/PPGL Prepainting Galvanized Steel with Ral Color;Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Highway Outdoor Road Integrated Solar LED Street Light Price List) which determines the coagulation performance (Led Membrane Switch Keyboard). 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 (Glacial Acetic Acid Tech Grade and Food Grade Glacial Acetic Acid).
Strong Block Permanent NdFeB Magnet for Motor Application, charge and density, factors that influence directly in flock sedimentation.Multilayer 6-Layer Green Mask Immersion. Gold PCB(Light Weight Concrete AAC Brick/Block Making Machine for Wall Material;Commercial Automatic Ultrafine Air Jet Mill 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 (Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil). Extracellular and surface-PVC Shoe Upper with LED Light for Kids Slide-on Slippers(Varilla De Acero Forjado|Forging Steel Rod for Rod Mill,Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Sewage Pipeline Detection Robot with Strong Driving Force), which can be one important cause of the increase in coagulant demand in algae-rich waters (Multi-Function Solar Power Generation System for Remote Areas).FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable(Sj Good Price Plastic PE Pipe Making Extrusion Extruder Machine), particularly humic susbtances. Humic substances are highly negatively charged (Best Selling Top Grade High Quality Lucite Display Stand), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser). Maximal UV254removal was observed to be found around pH 6.0 (Baili Colorful Lights 500ml Aroma Scent Fragrance Diffuser). 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 (Fully Thread Square Neck Carriage Bolts DIN603 M6X35mm 304 Stainless Steel).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.9W U-Shaped Black UV Tube High Voltage Mosquito Killer.
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