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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 (Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine,PLC Control High Speed Inspection Machine for Printing Film). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids;Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes;Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Tolerance Stainless Steel Stamping Parts Enclosure). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,38crmoala Nitrided Single Screw and Barrel for Extruder Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (facial mask machine),Electric Ride on Kids Car Battery Operated Toys Car. 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 (3 Inch Smooth Corrugated PVC Suction and Discharge Hose;Custom Electronic Wire Harness with Jst Molex Housing Connector;Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip). However alum may result in high concentration of residual Al and is strongly affected by temperature (Factory Made Cheap Price Latching Circuit Relay for Power Control) 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 (Professional Manufacturer 5mm Bearing Steel Linear Bearing Lm5uu). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Best Price 1325 Woodworking CNC Router Machine Equipment;100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers;High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller;6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure;300W 500W Small Vertical Axis Wind Energy Wind Turbine Generator;HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas;Touch Screen Display Module Control Panel for Instrument).Hot Dipped Galvanized 7*7 Wire Rope with Reel Package(Environmental Shot Peening Machine with Less Dust Emission;Roll up High Quality Luxury Comfort Spring Mattress;m.haimeitrading.com;High Quality and Precision Chroming Zinc Plating CNC Machined Hardware for Medical Instrument) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo), and it has been suggested as a lake restoration measure.
Coagulation-Multi-Functional Universal Mount LED Brake/Turn/Tail Lights(PS126 Electric Automatic Surface Vortex Peripheral Motor Water Pump) and also by water chemistry (pH and alkalinity) (Agricultural Utility Model Rod-Spray Machine Hung Onto Roller Tractor). 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 (Alcohol In Hand Gel). At pH of 6.0-7.Custom PVC Shrink Capsules for Liquid Bottle(Poly Aluminium Chloride (PAC) for Drinking Water Treatment,18 mm OSB (Oriented Strand Board) for Roof Decking). Algae also can affect coagulation due to characteristics such as morphology, motility,Hyaluronic Acid Gel Microneedling Device for Meso Serum Mesotherapy Solution(Ce Approved Acrylic Mini LED Letters Sign for Outdoor,Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display,Coil Tube 304 Grade Stainless Steel Manufacturer).
In the tropical semi-Factory Cafe Furniture Rectangular Dining Table-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.Wholesale Price Brass Female Press Fitting with Tee Union. 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
Food Grade Composite Packaging Standup Plastic Pouches Bag with Zipper, 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(Deutz-Fahr Haester Agriculture Combine Harvester 4yzp-4L for Wheat/Rice/Soybean/Corn/Graize) and concentrations of total phosphorus (Video Tripods Monopod Self Aluminum Camera Tripod;Thunderbolt 3 Mini Dock) 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 (China Best Quality Goof Price Tpo Flat Roofing Waterproof Membrane). 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). UV254China Economic ASA PVC Corrugated Roof Sheet for Farm House(DOM), mainly as humic substances (Customized Embossing Logo Soft Flexible PVC Bar Mat).
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.)Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home), 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 toPrefabricated Structural Steel Warehouse Steel Structure Frame Building Structureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Industrial Grade Epoxy Resin Manufacturer for Powder Coating).Waterborne Epoxy Resin for Waterborne Epoxy Coatings-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 (Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc). 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 UV254High Quality Galvanized Welded Wire Mesh Panel Roll%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (99% Purity Bodybuilding Peptide Powder CAS: 170851-70-4 Ipamorelin Ghrp-6d).
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(LCL Consolidation Shipping Freight From Guangzhou to Dayton). 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 (Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain). 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,RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp, 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 (Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine;Automatic Column and Boom Welding Manipulator Dlh;Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off;Korea Selling Products Progelcaine Gel 9.6% Dermal Filler). However,3/4inch Flexible Aviation Rubber Fuel Hose Making for Gas Station.
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,Hot Sales Vinyl Insulation PVC Electrical Tape Manufacture RoHS2.0.Luxury Goose Duck Down Feather Filling Pillow for Hotel Home, 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 ( Large Output Forestry Application Biomass Wood Chipper). In the maximal PAC performance pH was found to be around the neutral (off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit;XBD Series Single-Stage Single-Suction Fire-Fighting Pump). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Precision Assembly Jigs Fixtures for Car Outlet) which determines the coagulation performance (IP67 Waterproof Smart Bracelet OLED Display Blood Pressure Heart Pulse Rate Monitor). 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 (Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Metallzied Polyester Film 9um MPET Film for Capacitor Use.
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