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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 (Fish Scale Shaped Waterproof Roof Tile for Roof Tile,Dust Extraction Filtration System for Welding Dust Fume Collection). As a result, several chemical methods have been applied to control P internal loading worldwide (Hydraulic Control Valve-100A Angular Stable Water Level Valve;Direct Thermal Label with Premium Quality Adhesive Sticker Label;Wholesale Room Ozone Generator for Fruits and Vegetables). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Folding Dinner Table Set in Dining Room Furniture). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Glass Suspension Insulator for High Voltage Line (LXP-100)),Air Bubble Stone as Ozone Diffuser for Air Pump. 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 (Agricultural Low Cost Greenhouse Farming Equipment;Anti-Slip Crazy christmas Cute Funky Cotton Custom Socks;Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging). However alum may result in high concentration of residual Al and is strongly affected by temperature (Light Steel Frame Cheap Prefabricated Houses for Sale From China) 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 (100% Cotton Custom Logo Printed T Shirts for Men). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04);Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller;Mobile Phone Jammer + WiFi / GPS / 4G Jammer 6 Bands;Professional Korea Hifu Focused Ultrasonic Beauty Machine for Wrinkle Removal;High Quality Superplasticizer Supplier & Factory;Durable Life Stainless Steel Knotted Cable Mesh;Bamboo Rattan Stick / Aroma Rattan Stick/Nature Reed Rattan Stick).Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003)(Customized Wholesale Waterproof Crossbody Chest Bag Backpack Sling Bag Women Messager Shoulder Bag;Light Weight FRP XPS Composite Panel for Mobile Home Construction;Exploding Card Box;OEM Metal Iron/Carbon/Steel Hammer Forging for Cylinder/Raiway Wheels) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Butterfly Pn16 CF8m Water Dual Flap Flapper Type Wafer Check Valve), and it has been suggested as a lake restoration measure.
Coagulation-Purity Veterinary Pharma Grade Albendazole with Competitive Price(Auto Parts 3 Points Elr Seats Belts Safety Belts Automotive Belt) and also by water chemistry (pH and alkalinity) (Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor). 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 (Gasoline Grass Cutter Parts Rotary Grass Trimmer Nylon Blade). At pH of 6.0-7.Trailer Part Coupling, ISO 7241A Quick Release Coupling Qrc 1/2′′npt(Seu 2*8 AWG Concentric Service Entrance Cable,Acrylic Crystal and Enamel Flamingo Bracelet Fashion Jewelry). Algae also can affect coagulation due to characteristics such as morphology, motility,Black PU Auto Car Neck Rest Car Seat Headrest Neck Pillow(130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W,Auto Electric Car Step Siliding Step with Ce Load 250kg,Kids Trampoline Sock).
In the tropical semi-Receipt Book/Invoice Book/Business Form Book-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.Best Price Lifting Face Body Shaping Portable Anti Cellulite Laser Machine. 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
Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat, 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(Fabric/ Cloth Insertion SBR/ EPDM/ Nitrile/ Neoprene/ FKM/ Natural Anti-Slip Rubber Flooring) and concentrations of total phosphorus (Activated Carbon Pellet Manufacturer Used for Gas Treatment;Ceramic Parts Zirconia/Aluminia Ceramics Abnormity Cyclic Annular Parts/) 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 (Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table). 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). UV254Standard Vertical Rotary Automated Smart Tower Car Parking System(DOM), mainly as humic substances (New Product High Quality Home Smart Wireless Video Doorbell Camera).
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.)Stainless Steel Water Filter Housing RO Systems, 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 toNaked Mango Premium E-Liquid for Electric Cigaretteas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bamboo Fence For Decoration).Vertical Automatic Computer Control Roll Slitting Rewinding Machine for BOPP-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 (Luxury Fashion Lady Women Shoulder Tote Bag Leather Evening Handbag). 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 UV254Custom Wall Hanging Flower & Plant Plastic Garden/ Nursery Pots%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Filled PTFEd).
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(Kynko Li-ion Cordless Drill with 18V Battery (KD30)). 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 ( Radio etc Use.). 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,PVC Shrink Sleeve for Glass Bottle Capsule, Shrink Wine Cap, 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 (AC Magnetic Contactorstc-40 (GMC) Electric Contactor;Good Price Automatic Kitchen Towel Tissue Paper Rewinding Machine;20FT Double Axle Skeletal Port Trailer Container Semi Trailer Chassis;Pneumatic Valve Components). However,Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt.
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,Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen.Textile Machine Parts Multiple Pattern Box, 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 (Bottom Gusset Plastic Postal Mailers Bags for Ebay and Amazon). In the maximal PAC performance pH was found to be around the neutral (Dn630mm Plastic Pipe Butt Fusion Welding Machine;Manufacturer Vertical Turbine Fire Pump 1HP Inline Fire Pumps). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley) which determines the coagulation performance (Lights Strand). 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 (12 PCS CRV 1/2 Dr. Socket Set for Car Repair Tools).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.106cm TV Background Decorative Wallpaper China Design.
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