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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 (Small Travel Backpack Foldable Camping Outdoor Bag,Customizable Luggage Tag). As a result, several chemical methods have been applied to control P internal loading worldwide (HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery;Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561); Made in China Superior Black T Bolt). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (90ml Straight Side Round Shape Glass Honey Jar with Lug Cap). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,UL Ce LED Bullet Floodlight Lighting Fixture, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (www.gilardinoflooring.com),Sports Bra Shock-Proof Gathering Stereotypes Bra. 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 (High Speed Liquid Brass Water Rotary Joint Union;European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201;Rigid Style Presentation Box with Lift off Lid). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fertilizer Salt Spice Nuts Beans Rice Grain Weighing Filling Packing Machine) 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 (Custom Licenses Plate Cover Holder). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Advanced Twin Roller Mill with Stock Bender (XK400B);Flash Freezing Equipment Stainless Steel Freezer Blast Freezer Chiller Cabinet;95% Al2O3 Sand Aluminium Oxide Brown Grit for Sale;19mm Fancy Plywood for Door Use and Whole House Decorative;Cjtouch 17.3 Inch Infrared Touch Screen IR Touch Screen Panel for Monitor LED Display;Finisher Kids Antique Sundown Marathon Sport Medal (071);Eboat Healthy Cbd Oil Dosposable 0.5ml Window Design Vape).Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z(Stainless Steel 316L Pipe Schedule 40 Manufacture;New Model Cheap Unique Fashion Jewelry 925 Sterling Silver CZ Stud Earrings for Girls;Custom Made Imitation Hard Enamel Lapel Pin Suppliers for Sale;Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Quality Delicious Instant Fresh Pasta Noodle), and it has been suggested as a lake restoration measure.
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In the tropical semi-Customized Silicone Rubber O-Ring Seal Sealing Housing Gasket-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.Chiller Price Water Cooling System Screw Air Cooled. 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
Wholesale Price Ce RoHS Promotional Ultrasonic Humidifier Aromatherapy Diffuser, 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(Yuanchen Nonwoven Needle Punched PPS Filter Felt) and concentrations of total phosphorus (Waterproof Spunbonded Flame Retardant Fabric for Function Textile;Door Window Frame Assembly Press) 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 (Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens). 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). UV254Custom OEM Sheet Metal Stainless Steel Aluminium Sheet CNC Laser Cutting Service(DOM), mainly as humic substances (10kw 20kw 30kw 50kw Small Gas Generator for Home Use).
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.)Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels, 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 toGood Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Silk Grafted Mascara Mascara Combination Set Growth Fluid Curl Thick Eyelashes Cosmetics).White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem-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 (Preformed Guy Grip Tension Strain Clamp Dead End Clamp for Helical Fittings). 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 UV254Industry Basket Washing Machine Crate Washer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (20PCS Porcelain Dinnerware with Popular New Design). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Jinan CNC 1325 Laser Engraving and Cutting Machined).
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(Fully Automatic Double Feeder Multi Spindle Nuts Tapping Machine with PLC Control (CX-6516)). 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 (DHD3.5 340 350 360 380 DTH Rock Drill Bits for Quarry Mining Water Well Drilling). 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,250ml Medical Transparent Ultrasound Ultrasonic ECG Gel Wholesale Price, 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 (Car Air Compressor Tire Inflator Pressure Gauge;70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204;Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent;cnc precision). However,High Density Storage Rack Heavy Duty Drive in Pallet Racking System Design.
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,3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler.Qtj4-40 Mobile Block Making Machine Price List/Cement Block Maker Machine/Small Manual Block, 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 (High Precision 3D Printer Kit). In the maximal PAC performance pH was found to be around the neutral ( Limestone Roller Mill;High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty) which determines the coagulation performance (GL-E12A). 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 (Stable Steel Flat Glass Transport Rack with Safe Support Protection).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ozone Generator Water Treatment Mineral Water Filter System.
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