Another good meeting

We had a good meeting yesterday at Uni High.

Most of the discussion centered around cost-benefit analysis.

We set a few rules of thumb to help us think about the level of performance our nutrient recovery system should meet.

Operational Cost-Benefits

Benefits

Shrimp feed costs about 1$ US per kg. Thus every kg of feed we replace with periphyton (assuming growth and mortality in the pond systems feed periphyton remains the same) saves 1$ in feed.

Cost

Labor costs vary greatly and it's not possible to set one value for labor costs. For our purposes, we'll set a labor cost of 20$/day/person operating the system That's very high for most countries with large shrimp farming industries.

So in gross terms, to make the system operate without losing money, the farms need to recover 20kg (44 pounds) of periphyton per day of labor invested in operating the system. That's a lot of "goo" so we'll need an efficient system to make this work. Fortunately, we only need to move the periphyton a short distance (100' or less in most cases) from the canals to the ponds. According to the Aquamat literature, the growth rates on the mats will sustain this kind of harvest if we can harvest enough of them efficiently.

Other profits may come with ecocertifications and other benefits. Other costs will be involved in acquiring, deploying and maintaining the system. In the short term, let's focus on these core operating expenses and worry about those others later.

We also discussed some of the advantages and disadvantages of deployment strategies. One question that emerged right away was:

Should we:

a. design a substrate to be moved from the canals to the shrimp ponds or

b. design a substrate that can be scraped or shaken or somehow harvested.

Option "a" might provide a simple means of operation, but will require a replacement system to keep harvesting nutrients. That doubles materials costs for the same rate of nutrient removal from the canals.

Option "b" will require either a technical solution for harvesting and transferring the periphyton, or extra labor to take the substrate to the shrimp pond, remove the periphyton in the pond and then returning the substrate to the canals.

We covered some other ideas as well, but this is enough for now. We'll be looking for posts on the 4 topics the group suggested and suggestions and comments on the issues posted here.