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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 (430 Hot Rolled Stainless Steel Coil No. 1 Finish,Fr-1300c/Fr-1600c Masking Tape Jumbo Roll Cutting Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality Industrial Grade Anhydrous Sodium Sulfate;Custom Logo Small Beer Mug One Ounce Mini Stein Glass;Certified Factory 304 Stainless Steel Corrugated Flexible Yellow Natural Gas Hose). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Empty Toner Lotion Pump Glass Bottle Cosmetic Bottles). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Electrical Insulation Flexible Crepe Paper Tube for Transformer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Wholesale Price Stainless Sand Blasting Grit),Custom Souriau Connector Header with Cable. 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 (Apple Shape Kneading Shiatsu Massage Pillow with Heating;Paint Spray Booth Air Flow Vehicle Paint Booth for Sale;Best Price 3D PVC Wall Panels Colored for Decorative and Art). However alum may result in high concentration of residual Al and is strongly affected by temperature (Diesel Engine Mobile Rotary Screw Scroll High Pressure Air Compressor) 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 (gjmach-chn.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2019 Wholesale ABS Hospital Medical Emergency Empty First Aid Kit Box;Compatible for Nellcor/Neusoft Reusable SpO2 Sensor Adult/Neonatal Finger Clip SpO2 Sensor;201 Stainless Steel Coil /Stainless Steel Sheet /Stainless Steel Plate;Transformer Silical Gel Breather DIN -42567 Form C;CNC Precision Sheet Metal Fabrication Custom Aluminum Sheet Metal Housing;Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts;SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer).Height Adjustable Removable Foldable Feeding Baby High Chair(Chocolate High Speed Automatic Feeding and Packing Line;Antitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Label;Latex Free Surgical Gloves;Discount HOWO High Pressure LPG Delivery Dispenser Truck) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Precision CNC Machined Part Aluminum Stainless Steel Components), and it has been suggested as a lake restoration measure.
Coagulation-High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair(Building Material Stone Tile Full Body Marble Porcelain Tile) and also by water chemistry (pH and alkalinity) ( 5.0mm Disk). 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 (PVC CPVC UPVC HDPE PE Plastic Water Hydraulic 16-63mm Double Pipe Making Machine Price). At pH of 6.0-7.Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory(High Speed Four Shafts Auto Exchange BOPP Tape Cutting Machine,Push up Breast Enlargement Bra SGS Test Certificate Backless Adhesive Silicone Bra Transparent). Algae also can affect coagulation due to characteristics such as morphology, motility,Carbon Steel Zinc Countersunk/ Flat Head Self Tapping Screw(Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts,Updated Stylish Peristaltic Biogas Pump Gas Booster Pump,Fishing Backpack).
In the tropical semi-Factory Supply Concrete Pump Spare Parts S Valve for Putzmeister, Cifa, Schwing, Sany Pump Truck-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.Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10. 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
Sell High Quality Food Grade Sodium Carboxymethyl Cellulose CMC, 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(Cosmetic Raw Materials 3-O-Ethyl Ascorbyl Ether Powder CAS 86404-04-8) and concentrations of total phosphorus (Hot New Kids Machine High Quality Self-Control Cat Mechanical Parts Swing Carnival Rides for Sale;High Efficiency Ice Block Maker High Quality Supplier) 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 (High Quality of Glassware Bottle of Essential Oil Reed Diffuser Perfume). 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). UV2548 Cylinder 4 Stroke 2560kw Zichai Zc8270 Series Marine Diesel Engine (ZC8270ZLC)(DOM), mainly as humic substances (Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet).
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.)New Model Solar Room Lighting System Lighting Kit Light in Remote Area, 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 toPVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rollsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Molybdenum Strip).Delight 15W Sensor+Night Sensor Solar Garden Lamp-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 (Auto Parts Nitril Rubber Bellows with Competitive Price). 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 UV254PP Surface Self Adheisve Roof Underlayment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fused Silica Flange with High Temperature Resistance). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Channel nutd).
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(Js500 Twin-Shaft Concrete Mixer for Block Machine). 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 (China Construction Machinery Sheet Metal Parts Manufacturers CNC Auto Parts). 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,2019 LCD PRO Hot Ionic Straightening Brush (Q20), 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 (Mimaki SB210 Dye Sublimation Ink for TX400-1800D Inkjet Printer;Exchange Table Plate Round Square Metal Fiber Laser Tube Cutting Machines;630kgs Galvanized Suspended Platform;Personalized Mens Jewelry Box). However,Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor.
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,Jumbo Roll Two/Double Sided Coated Solvent Base Tissue Tape (DTS10G-11).Police Disposable Nylon66 Handcuff with Two Loop, 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 (Schedule 40 Stainless Steel 304L Pipe and Tube). In the maximal PAC performance pH was found to be around the neutral (Auto Parts Engine Cooling Air Conditioner OEM 88450-26120;New Slip Resistant Waterproof Spc Vinyl Laminate Tile Flooring). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (100W/150W/200W Industrial High Bay UFO LED for Tennis Court Lighting) which determines the coagulation performance (Basketball 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 (Eeto Laser Metal Sheet Fiber CNC Laser Cutting Machine Price).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit.
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