Category: System Evaluation

Lesson Learned: Technology Selection

7/11/2016

Problem: A greenhouse facility wants to reuse water from a flood floor which is used to water potted plants. The water collected has vermiculite and organic matter clouding the water which would clog nozzles and settle in pipes.

Solution: The operator looked at two different technologies, a self-indexing filter and a parabolic filter screen (Figures 1 & 2). Both are recommended units that filter coarse material from water.

Figure 1: Diagram of a self-indexing filter [level sensor is tripped when water rises due to clogged paper and roll is unspooled]

Figure 2: Diagram of a parabolic filter screen [(a) inflow; (b) flows onto screen; (c) waste remains on screen and treated water falls through; (d) waste exits through tray; (e) treated water exits through (f); (g) water overflows if screen becomes clogged and exits through (f)]

Discussion: The infrastructure required for either technology is similar; both will need some plumbing and a pump to move water through the treatment system. The technologies are compared in the table below. Both systems will complete the task; the self-indexing filter is more hands-off but requires more inputs. The parabolic filter screen must be supervised but has minimal on-going costs.

Decision: The operator choses the self-indexing filter as it requires less regular supervision. The additional energy costs, on-going need of paper rolls, and disposal of paper was preferable to increased labour requirements and disposal of waste.

Lesson Learned: When there are multiple technologies that could fit in a treatment system it is important to investigate all aspects. Decisions should be made based on more factors than merely cost.

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Flow Monitoring

7/6/2015

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Flow monitoring is an important component of a water management plan. It is useful to know the volume of water that is used while washing and processing as well as the volume that is discharged as waste. If the flows within the processing and washing facilities are monitored it may be possible to identify inefficiencies or opportunities where less water could be used. A complete understanding of water use within the plant can provide new information that can help with implementing recycling and reuse of washwater.

Figure 1: Flow meter and logger unit (left), flow meter attached to a circular pipe band (center), and installed flow meter (right)

If discharging is unavoidable flow monitoring is still very important because when considering wastewater treatment it is crucial to know what volumes will require treatment. The less water the better, and generally less expensive. Volumes are needed, along with pollutant concentrations, to calculate the loading of waste into a treatment system. This information is also vital for selecting a water treatment technology that will be suited to treat the washwater.

Figure 2: An example graph showing data collected by a flow meter

There are several ways to monitor flow. A simple option is to use the flow rate of a pump and the amount of time it runs to estimate flows. Flow meters are an accurate and easy way to monitor flow, but they can be expensive. However, when a complete water management plan is being developed it is worthwhile to invest in proper flow monitoring equipment. By understanding the volumes of water used on a farm finding ways to decrease water-use and treat washwater becomes much easier.

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Lesson Learned: Technology Selection

Flow Monitoring

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