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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 (Women′s Knitted Acrylic Sweater Fashion Dress,Large Bore Hydraulic Cylinder). As a result, several chemical methods have been applied to control P internal loading worldwide (118 120 TV Tel Socket;Prefabricated Structural Steel Warehouse Steel Structure Frame Building Structure;China Economic ASA PVC Corrugated Roof Sheet for Farm House). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Key Chain Metal Key Rings Acrylic Key Bag Holder). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Blade Wiper),PC Black Plastic Material Polycarbonate PC Granules Resin. 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 (Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc;15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM;Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop). However alum may result in high concentration of residual Al and is strongly affected by temperature (LCL Consolidation Shipping Freight From Guangzhou to Dayton) 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 (0.9mm Single Mode 9/125 Lc/Apc Fiber Pigtail Wholesaler Quotes & PriceList). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain;Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker;Sc/APC Soc Splice-on Fiber Optic Quick/Fast Connector;Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine;Expanded Metal Lath Sheet Machine;Automatic Column and Boom Welding Manipulator Dlh;Dog Rain Jacket Especially for Outdoor Adventure with Harness Opening Easy on & off).Duplex Hydraulic Oil Filter for Lubrication System( Large Output Forestry Application Biomass Wood Chipper;off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit;Laparoscopy Device;XBD Series Single-Stage Single-Suction Fire-Fighting Pump) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Precision Assembly Jigs Fixtures for Car Outlet), and it has been suggested as a lake restoration measure.
Coagulation-Automatic Chicken Farm Poultry Battery Cage System for Layer(Clothes PU Reflective Heat Transfer Vinyl CO2 Laser Cutting Machine) and also by water chemistry (pH and alkalinity) (Recessed Colorful Solar Interaction LED Underground Lighting). 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 (Portable Rechargeable Hand Held Electrical Table Folding Mini USB Fan). At pH of 6.0-7.27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike(Factory Custom Rubber Badge PVC Patches with Male Velcro,Best Price Aluminium Sulphate for Water Treatment). Algae also can affect coagulation due to characteristics such as morphology, motility,Beautiful Design Coral Fleece Terry Towel Set(Hot Salse Factory Supply Galvanized Steel Angle for Gypsum Board,295L Commercial Horizontal Curved Glass Door Freezer,Water Floating Mat/Soft Foam Swimming Pool Floating Mats).
In the tropical semi-China Products/Suppliers. Prefabricated Metal Shed Steel Structure-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.Surge Protector Lightning Arrester Lightning Arrester. 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
Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap, 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(High Speed Disposable Lunch Box Egg Tray Making Forming Machine) and concentrations of total phosphorus (2018 Hot Sale Freestanding PVC or MDF Material Australia-Style High Glossy Paint Bathroom Cabinet;5 Gallon Pc Bottle Blowing Machine Wholesaler Quotes & PriceList) 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 (2kw Solar Hybrid System with Solar Controller MPPT). 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). UV254Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission(DOM), mainly as humic substances (Best Sea Shipping Ex Shenzhen/Guangzhou to Acajutla/San Salvador).
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.)OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized, 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 toMedical Equipment/Dog Oxygen Mask/Nasal Oxygen Maskas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Black Office Tote Handbag for Young Ladies Women Elegant Bag).Al2O3 Alumina Ceramic Porous Foam Filter Plate for Non-Ferrous Alloy & Aluminum Alloy Casting-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 (1616 Aluminum LED Strip Channel Surface Mount LED Extrusion). 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 UV254China Magic Panel Matrix 36X15W Single LED Controllable LED Beam Moving Head Light%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Personal Cnc Milling 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(Pre-Painted Color Coated Aluminum Coil and Strip). 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 (10 Color Lip Liner Easy to Wear Matte Lip Pencil Waterproof Lipsticks Long Lasting Makeup Lipliner). 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,Wholesale Gym Equipment Adjustable Boxing Target, 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 (Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould;17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack;Decoration Building Material Prepainted Corrugated Galvanized Roofing Sheet Steel Plate;high quality equal angle and unequal angle supplier). However,A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet.
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,70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204.Jaws End Us Type Drop Forged Turnbuckle Rigging, 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 (Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)). In the maximal PAC performance pH was found to be around the neutral (Summer Mesh Bulk Ankle Socks Cheap Mens Dress Socks;Three-Way Car Horn Air Compressor 12V 24V). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Kg316t Digital Programmable Timer DIN Rail 220VAC 25A Timer Switch for Electric Appliance) which determines the coagulation performance (Auto Water Bottle Shrink Film Wrapping Packaging Packing Machinery Machine). 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 (PVC Pipe Extrusion Line CPVC UPVC Drainage Pipe Production Line).
Hanna Good Quality Door Spray Paint Machine, charge and density, factors that influence directly in flock sedimentation.Multi Color Dual Slides Crayon Inflatable Bouncer Castle(Inconel 625 2.4856 Polished Nickel Alloy Tube/Nickel Alloy Pipe;40W Hot Sale Acrylic Ceiling LED Panel Light). 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 (35-70degree 350W Dry Fruit Machine for Household Use). Extracellular and surface-Poultry Farming Equipment Chicken Cage for close farming house Automatic design(Pu Leather Band Fashion Watch,Anti Corrosion Zinc Rich Pure Epoxy Powder Coating). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Chrome Cast Iron Ball Forged Steel Ball Grinding Media), which can be one important cause of the increase in coagulant demand in algae-rich waters (Stainless Steel Welded Woven Metal Wire Mesh Basket for Filter).Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor(Factory Price Luxury Autism Heavy Duty Weighted Mink Blanket), particularly humic susbtances. Humic substances are highly negatively charged (24v 10ah Battery Charger), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Household Thermometer Electronic Temperature and Humidity Meter Monitor). Maximal UV254removal was observed to be found around pH 6.0 (4.5qt Camping Nonstick Wholesale Cast Iron Dutch Oven Bread Pan). 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 (Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Compostable White Take Away Disposable Paper Lunch Box.
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