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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 (Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine,Promotional Enamel Teapot). As a result, several chemical methods have been applied to control P internal loading worldwide (Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair;Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress;Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (45 Degree Angle Cutter),Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074). 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 (Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019;New Design Artificial Leather Fabric PVC Leather for Furniture (1008#);Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning). However alum may result in high concentration of residual Al and is strongly affected by temperature (Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275) 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 (Igs Fish Hunter Fish Shooting Game Machine with Plush Chassis). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Blackboard Imprint Unique Glass Drinking Jars for Canning;1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine;High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic;Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;High Quality CEO Working Executive Office Desk (SZ-ODL301);Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine;High Quality Custom Design China Plastic Injection Molding Factory).J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter(Pre-Heated Copper Coil Pressure Solar Water Heater Equipment;Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale;Synthetic Filter Media Supplier & Manufacturer;Hot Selling SAA Rcm Listed CCT Changeable LED Down Light) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades), and it has been suggested as a lake restoration measure.
Coagulation-Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown(Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle) and also by water chemistry (pH and alkalinity) (20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen). 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 (Floating Book Shelf). At pH of 6.0-7.PP Woven Bag/Sack for Rice/Flour/Food/Wheat 40kg/50kg/100kg, Pol.(Manufacturers Supply Through Hole Right Angle USB 1394 Connectors,Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo). Algae also can affect coagulation due to characteristics such as morphology, motility,Jinfeng H Type Best Price Poultry Farm Egg Layer Chicken Cages(Factory Directly Sale Virgin Kraft Liner Paper Machines,Special Offer Stock Primary School Uniform Shirt for Boys,2017 XCMG Official High Quality Truck Crane 16ton Xct16).
In the tropical semi-High Speed Spiral Dough Mixers 50kg Flour for Bread-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.Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump. 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
Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect, 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(Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts) and concentrations of total phosphorus (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer;Customized Clasp bracelet) 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 (Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon). 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). UV254Universal Cable Fault Testing Instrument Tester / Analyzer(DOM), mainly as humic substances (Custom Stand up Composite Material Zipper Packaging Bag Candy Bag).
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.)3600 Rpm Concrete Machinery Ride on Power Trowel Factory, 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 to Asphalt Mixing Plantas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Solid Wooden Home Furniture Vanity Bathroom Cabinet Set).20 Cavity Pet Preform Mould with Competitive Price-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 (Flat Pharmacy Cylinder Shape Pet Plastic Pill Containers Capsule Bottles for Sale with Metal Cap). 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 UV254Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Induction Heater Electric High Temperature Furnace for Casting). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Weifang Manufacturer 30kw Diesel Generator Set Powered by Ricardo Weichaid).
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(Baby Teething Toy Wooden Bunny Round Ring Teether). 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 (FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia). 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,Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type), 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 (New Arrival Sports Anti UV Protective Arm Sleeves;HVAC Connected Large Area Scent Diffusion System with 2 Bottle;Fashion Leather Wristband USB Disk 4GB to 32GB;Sheet Tire Frame Top Quality Rubber Products Making Machine). However,New Product PVC Insulation Tape, Fire Resistance Electrical Tape, PVC Electrical Tape (BK-1-217).
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,Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost.Modern Leisure Chair for Europe, America and Asia with Armrests, 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 (Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag). In the maximal PAC performance pH was found to be around the neutral (Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant;Eco Brava Small Mud Interlock Brick Press Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing) which determines the coagulation performance (Factory Custom LED Display with RGB LED Display Panel for Wholesale). 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 (Textile Machine Parts Multiple Pattern Box).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt.
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