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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 (Stainless Steel Industrial Agitator Detergent Soap Liquid Mixer,6314c3 Deep Groove Ball Bearing Low Noise for Motor). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality 2mm 3D Printing ABS Plastic Prototype Manufacturer;Naked Mango Premium E-Liquid|Nicotine Salt for Electric Cigarette;Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hsc8 6-4A Mini-Type Self-Adjustable Crimping Plier). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ceiling Type, Heat Recovery Air Handling Units, HVAC System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fibermania 19 Inch 1u CAT5E UTP 12 Ports Patch Panel),Free Sample High Quality GSM External Antenna. 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 Density Wood Grain Fiber Cement Board;1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar;Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cow Horse Trailer Ramp Stall Stable Rubber Mat) 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 (Round AISI Tube Prices 304 Stainless Steel Pipe). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hydrochloric Acid (HCl) ;Flexible Aluminum Protecting Rolling Curtain Shield Bellows Cover;7 Liters Vertical Type Commercial Butchery Manual Sausage Filler;Mica Fiberglass Braided High Temperature Electric Power Cable;Food Shop Desktop Frozen and Cooked Meat Slice Cutting Machine;Manufutuer Promotes Skin Regeneration Repair Anti Aging Smoothing Fine Lines Facial Mask;Portable Animal High Frequency X Radiography Machine (HP-HFX600V)).High Speed Liquid Brass Water Rotary Joint Union(Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold;Cement Bag Manufacturer Kraft Paper Valve Bag for Cement;Hdg Carbon Steel Hex Nut;Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag), and it has been suggested as a lake restoration measure.
Coagulation-High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line(PC260 3.0-24V 24*27mm 3W DC Motor for Electric Garden Tool) and also by water chemistry (pH and alkalinity) (LED Dancing Wing Props Halloween Christmas Party Supplies). 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 (Wireless Charger PCBA Board China Shenzhen Supplier). At pH of 6.0-7.PVC Laminated Tarpaulin for Tent PVC Vinyl Tarpaulin Vinyl Rolls(Glass Shower Door Frame Waterproof Seal PVC Seal,2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter). Algae also can affect coagulation due to characteristics such as morphology, motility,Juice Filling and Canning Machine/Juice Maker Machine/Juice Machine(Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel,12mm Multiwall Green Perforated Hollow Polycarbonate Sheet,Police Concealable Bullet Proof Vest (Aramid Ballistic Panel)).
In the tropical semi-Flexible Arm India Tapping Machine for Industrial Production-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.OEM Trailer Parts Drop Axle Forging Spindle. 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
Fashion Italian Style Hotel Furniture Wooden Marble Dressing Table, 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(1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD) and concentrations of total phosphorus ( NdFeB Magnet for Motor (N38H);Tungsten Carbide Chip Inserts) 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 (Long Sleeve Safety Working Clothes Professional Safety Working Clothes). 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). UV254Automatic Continues Iron Wire Straight Line Wire Drawing Machine(DOM), mainly as humic substances (Customized Ring Die for 560/508/420/350 Pellet Machine).
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.)Black Bracelet Leather USB Drive Free Design Logo, 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 toDn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuatoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fabric Production Line).Waterproof Magnesium Oxide False PVC Ceiling Panel-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 (Ferrous Sulphate Heptahydrate for Water Treatment). 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 UV254Refrigerant R134A with Refillable Tped Approved Cylinder%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Flexible Semiauto Cosmetics Bottles Adhersive Labels Sticker). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Construction Material Wood Plastic Composite WPC Solid Square Bard).
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(Chicken Layer House Design for Poultry Farming with Equipment). 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 (Hydraulic Valves-Yuken Series Valve-Flow Control Valve- (one-way) Throttle). 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 Cross Joint Pipe Fittings Equal Pipe Cross, 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 (PVC Shrink Sleeve for Glass Bottle Capsule;High Energy Wet Pulverizer and Wet Powder Mill;Aerospace Industry Cutter Systems/ Equipment Cutting Plotter CNC Cutting Machine;Machine Bolts). However,Electrical Insulation Flexible Crepe Paper Tube for Transformer.
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,Custom Souriau Connector Header with Cable.Height Adjustable Removable Foldable Feeding Baby High Chair, 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 (Hot Sale and Good Quality Playground Artificial Lawn for Soccer). In the maximal PAC performance pH was found to be around the neutral (0.7kw Dereike Dhb 220b D70 Air Pump for Central Vacuum Systems;Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (OEM Custom 2pieces Car Rims 17 18 19 20inch Forged Car Alloy Wheels) which determines the coagulation performance (Rush Delivery Epoxy Resin Curing Agent for Polyester Systems). 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 (Pet Strapping Belt Making Machines/Pet Packing Straps Extrusion Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10.
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