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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 (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine,www.sunllent-solar.com). As a result, several chemical methods have been applied to control P internal loading worldwide ( 24-380VAC Single Solid State Relay;Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory;Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2 Way Intercom Systems Smart 32g Memory Video Doorbell with Door Unlock Time Delay),USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer. 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 (Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress;Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows;Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). However alum may result in high concentration of residual Al and is strongly affected by temperature (Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019) 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 (Nibco Check Valve). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Design Artificial Leather Fabric PVC Leather for Furniture (1008#);Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning;Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275;Blackboard Imprint Unique Glass Drinking Jars for Canning;A4 Size Office Ecofriendly PP Plastic Colored Expanding File Folder Pocket Display File Folder;1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine;High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic).Polyester/PP Short Fiber Needle Punched Non Woven Geotextile Fabric, Low Price(Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine;Badminton Product;High Quality Custom Design China Plastic Injection Molding Factory) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Pre-Heated Copper Coil Pressure Solar Water Heater Equipment), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Chinese Sax / Tenor Saxophone, High Quality, Made in China(Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale) and also by water chemistry (pH and alkalinity) (Hot Selling SAA Rcm Listed CCT Changeable LED Down Light). 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 (65-3 Hydroxypropyl Methyl Cellulose). At pH of 6.0-7.Wholesale Wehappy Silicone Baby Training Toothbrush Set with Blister Card Package(Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades,Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle). Algae also can affect coagulation due to characteristics such as morphology, motility,Garden Metal Natural Rusty Flower Decoration Product(20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen,Manufacturers Supply Through Hole Right Angle USB 1394 Connectors,White Powder Calcium Chloride for Snow Melting Agent).
In the tropical semi-LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter-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.38cc Petrol Chain Saw Wood Cutting 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
High Chrome Cast Iron Mud Sand Slurry Pump Parts, 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(Special Offer Stock Primary School Uniform Shirt for Boys) and concentrations of total phosphorus (12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery;Six Bolts Bogie) 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 (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer). 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). UV254Best Seller Sex Pregnant Women Adult Sex Dolls Adult Love Doll Softest 158(DOM), mainly as humic substances (Aol CNC 1625 Cutting Plotter for Corrugated Cardboard).
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.)Modern design Prefab Steel Structure Livestock Farm for Layer Chicken and Broiler, 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 toNew Model Solar Room Lighting System Lighting Kit Light in Remote Areaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Paint Room Wholesaler Quotes & PriceList).Custom Black-White Printed Product Operation Instruction-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 ( Asphalt Mixing Plant). 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 Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Efficiency Filter Water Filter with Water Treatmentd).
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(Flat Pharmacy Cylinder Shape Pet Plastic Pill Containers Capsule Bottles for Sale with Metal Cap). 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 (Induction Heater Electric High Temperature Furnace for Casting). 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,Disposable Polypropylene Protective Head Wear Bouffant 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 (FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia;CNC Machining Aluminum/Stainless Steel/Copper Filler Necks Flanges;Hot Sale 99% Powder Form CAS 70288-86-7 Ivermectin with Best Price;Automatic 3d Printer). However,Plastic Injection Molding Machine for Nylon Cable Tie Mould Making.
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,Hotel Dental Kit Toothbrush Shaving Kit Razor Amenities Sets.Factory Price Gerneral Usage Silicone Sealant, 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 (New Arrival Sports Anti UV Protective Arm Sleeves). In the maximal PAC performance pH was found to be around the neutral (HVAC Connected Large Area Scent Diffusion System with 2 Bottle;Fashion Leather Wristband USB Disk 4GB to 32GB). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag) which determines the coagulation performance (Fiber Reinforced Plastic FRP Grille for Double Deck Floor). 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 (Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant).
Yonglian Yl003f European Standard Power Cord with VDE Certificate Approved, charge and density, factors that influence directly in flock sedimentation.High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts(Eco Brava Small Mud Interlock Brick Press Machine;7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Textile Machine Parts Multiple Pattern Box). Extracellular and surface-Manufacturer New Design Reusable Clear Lalique Glass Perfume Packaging Bottle(0.7MM WIRE,Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Accept Customization Perfume Direct with Good Price), which can be one important cause of the increase in coagulant demand in algae-rich waters (AAC Autoclaved Aerated Concrete Brick Making Machine).Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice, Seasoning(Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter), particularly humic susbtances. Humic substances are highly negatively charged (wire brush made in China), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette). Maximal UV254removal was observed to be found around pH 6.0 (FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve.
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