Hort 2374 Greenhouse Construction

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Ergonomics- study of body in the work place

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Why? Saves labour, injury prevention, time saving, doing more with less energy, safety, longevity, reduce miedical expenses, reduce insurance costs.

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Ergonomic questions to ask when analyzing.

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Does the task need doing? Are tasks arranged in the best order? Arm they being performed correctly? Are you walking too far? Is everything close to hand? Are plants handled too often? Is there excessive downtime?

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Other benefits of ergonomics

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Better work environment, people work better in healthy environment and a healthy posture.

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What is a buffer conveyor?

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An extended conveyor belt that allows for buildup of product so that you don't slow down the processing machine.

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Reverse osmosis-

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If the main problem is high levels of sodium and boron, then this is a good option.

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Chlorine- General purpose disinfectant.

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Ph must be brought down to between 6 and 7 in order to react with organic materials. Levels below 6.0 are dangerous and can reease chlorine very fast.

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Chlorine dioxide

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A mix of chlorine and acid which is mixed into a water distribution system- effective against micro-organisms in water and biofilms. Dangerous- it can form chlorine gas

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Hydrogen peroxide-

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Used to kill water-borne pathogens and their dormant spores caused by algae, bacteria and biofilms.

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Ozone-

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Ozone- it is produced onsite. If done correctly it is very effective at cleaning water, added benefit, it increases oxygen content of water more than pure oxygen does!

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Fast sand and filter Ad and disadvantage

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Advan- Cheap, easy to maintain(auto backflush), removes large particles.

Disadvantage- Only removes particulates, requires frequent maintenance

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Slow sand filter- advantages

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Advantage- Biological- safe, easy to build, relatively inexpensive to install, removes most fungal pathogens, suitable for small operations. No pretreatment required. No effect on nutrient levels.

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Slow sand filter- disadvantages

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requires annual maintenance. Requires large area(25 metres sq./ ha). Slow flow rate means you need a storage tank. Effectiveness dpends on design. Less effective on viruses and bacteria.

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Lava rock filter- advantages

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Biological system, similar to slow sand filter. Faster flow rate than slow sand. Less maintenance= less cost. Low capiital cost( $35,000 for 6 acres)

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Retention ponds/ reed beds advantages

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Biological system. It removes most fungal pathogens. Cheap to build

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Retention ponds/ reed beds disadvantages

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Requires large area of land. It provides low flow rates.

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Ultra-filtration-

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Advantages- Physical treatment- safe. Low maintenance. Disadvantage- Very slow rates and can clog easily.

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Micro-pore filtration advantages

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Very fine membrane- Removes most fungi including pythium. Physical= safe. Simple contruction. Handles large volumes of water.

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Micro-pore disadvantages-

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Costly(40,000- 50,000)

fails if membrane ruptures.

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Chlorine treatment

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Advantages- low cost and simple to install

Disadvantages- requires you to buffer water to 5.5-6. Chemical- safety isseues. Requires 30 min dose time. Affects nutrients in water(can reduce Fe, Mn availability). Toxic. Corrosive, requires holding tank

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Iodine filtration

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Advan- requires less contact than Cl.

Disadvantage- Needs a pre-filter, including carbon treatment. This removes Fe, Cu. Poor reliability.

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Copper filtration advantages

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Effective against fungal pathogen root rots.

No chemical to add

Can treat large volumes of water

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Copper disadvantages

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Need to replace electrode every 4 years.

May be considered pollutants.

There is a lack of research.

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Soaps, wetting agents as water treatment

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Advantages Cheap and can kill some baterial problems(lettuce big vein.)

Disadvantage- Phytotoxicity risk. Not effective against all fungi, bacteria, and viruses.

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Ozone water treatment advantages

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20x more reactive than Cl. Broad, but not complete spectrum kill. Fast acting- quick kill. Increases dissolved 02 in water. Improved root growth. Low maintenance cost. Its environmentally friendly :)

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Ozone water treatment- disadvantages

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Expensive(40,000-50000). It requires a pre-filter to remove organic materials. Chemical- it can be phytotoxic if not allowed to return back to 02. Buffer water to pH of 4.0- 4.5. It can remove Fe, Mn. Requires a holding tank. Needs a power supply.

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Hydrogen peroxide treatment advantages

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Advantages- breaks down to water and free 0. Low capital cost. Simple system. Broad spectrum killl. No holding tank required. Controls pythium and liverwort. Cleans irrigation lines. Improves root health(increased 02)

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Hydrogen peroxide treatment disadvantages

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Less effective against bacteria and viruses. Not as reactive as 03(OZONE). may need extra activators. May react with Fe. Possible phytotoxicity. Diffficult to control dosage rate. High long-term operating costs.

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Ultra-violet radiation advantages ( high pressure/ low pressure lamps) 200-280 nanometers - 254 is boss

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Simple, effective against 99% fungi. what a fun guy! Less running costs than heat. Healthy roots develop.

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UV radiation disadvantages

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High maintenance- Needs a pre-filter(clear water). Slow flow rates. Lamps degrade. Can cause Fe precipitation. Kills beneficials too. High costs($20,000-70,000).

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Magnetic effects as water treatment

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Advantages-Dissolves minerals in irrigation lines, no parts to maintain. May soften water.

Disadvantages- Unproven technology. Needs prefilter.

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Ultra-sound

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Advantage- Non-phytotoxic.

Disadvantage-Requires high cooling. Expensive(more than pasteurization.) Limited volume capacity.

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Reverse osmosis

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advantages- Environmentally safe. Proven system- used by many municipalities. Simple to install.

disadvantages- can be expensive. Affects nurtient content in water

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Pasteurisation-(85 degree C for 3 mins. or 96 degree C for 30 sex) advantage

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Simple. Broad spectrum. No holding tank required. Low maintenance.

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Pasteurisation disadvantage

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Expensive(20,000-60,000). High operating costs. Needs pre filter. Need to cool water before it goes back to crop. Treat water to pH 4.5. May kill beneficials too. Reduces 02 content of water