An Alternative Design

In the club meeting this week we discussed Liz’s proposed design.
http://i710.photobucket.com/albums/ww101/theodore1800/design1v1.jpg

It has many positive qualities and works as an excellent starting point (thanks, Liz!)
Main Structure.
Working from this design, I created a similar structure. This design consists of a less sturdy structure, as I use the PVC piping primarily to keep the aquamats from moving and to allow for easy removal of aquamats for replacement. According to http://www.nurturetech.net/aqua.htm, aquamats are equipped with ballast bags to keep them in place, but the PVC structure could allow several aquamats to be removed from the pond at the same time. This structure, consisting of a primary pipe paralleling the side of the effluent canal and perpendicular secondary pipes that the aquamats slip over, is attached to bank of the canal by ropes. One end of a rope would be tied to the primary pipe, and the other end would be tied on a stake on the side of the canal. This means the entire structure can be removed.
Details.
Each unit stemming from the primary pipe is connected by a tee and consists of one PVC pipe, one aquamat, and one cap. The PVC pipe length is slightly longer than the top of the aquamat. For the present, my idea for attaching the aquamat to the pipe would be to fold the top over to create a tunnel. I still need to work out exactly how this could be done, one option would be to sew this pocket in the aquamat; another option would be to use some kind of adhesive or pin to secure this tunnel. The aquamat would be kept from sliding off the PVC pipe by the cap. The top of each unit will be roughly equal to the surface of the water because of the floatation element associated with the aquamat.
Removal of substrate.
This design offers several different options for removal of organisms. I will briefly outline a few of them (discussed in our latest inventor’s club), and eventually follow up with more details.
1. Remove the entire structure and place in shrimp pond. Pros: this way we can utilize organisms growing both on the aquamats and the primary pipe. Cons: time must be allowed for the shrimp to eat off the structure
2. Remove entire structure and strip organisms by hose or rake. Pros: allows for faster cycle than in option 1. Cons: labor
3. Remove aquamats only and strip organisms by hose or rake.
4. (Inspired by Mr. Smith) Leave entire structure in the water, and move down the middle of the canal scraping all of the aquamats in sort of one swoop (this would only work with careful spacing of the aquamats, and we would have to develop a way to collect the substrates in the water). Pros: quick and dirty, Cons: we need to look into this further to be more specific. Hard to describe, so included a brief video demo- the spatula with basket represents the scraper tool (more on that later), the sticky notes are aquamats.

Pictures

Apologies for the strange model. PVC pipes represented by chopsticks, caps by pencil toppers, aquamats by cut paper, water by blue towel, rope by red yarn, PVC tees by masking tape.

http://i710.photobucket.com/albums/ww101/theodore1800/design1v2.jpg

http://i710.photobucket.com/albums/ww101/theodore1800/Overview.jpg

Credits: Thanks to CorelDRAW and Paint for graphics, http://www.irrigationtutorials.com/instal05.htm for hardware knowledge, http://www.nurturetech.net/aqua.htm for aquamat information, Mr. Smith for inspiration and wisdom, Liz for original design

Possible Starting Point for a Design

Post by Allen

After Tuesday's meeting, I thought of a simple design that might serve as a good starting point. I built frame for meshing to collect nitrate with PVC piping and it cost $6 total, although I had some left over. The box is 2 ft. x 2 ft. and the part that sticks out is 15 in.
It was very easy to assemble, I was able to cut the pieces and put it together without help, and it took about 45 minutes.


Image link: http://i289.photobucket.com/albums/ll219/amariah118/Inventors%20Club%20Competition/IMG_7359.jpg


This is an overview picture - I tried labeling each piece of PVC and also the joints, I hope you all can see it. Everything is 1/2 in. pipes, except "top" and "bottom", which are 3/4 in. and meant to slide over the 1/2 in pipes that they are placed above and below of, #5 and #6. "Top" and "bottom" will have mesh between them, so when you slide it over #5 and #6, it will be held out in the water. Joint "E" is where the whole thing will be hung, so you can easily have as many as you want of these in a row. To remove the "top" and "bottom" bar: when it is hanging in the water, you press on #1, so the whole thing will rotate, and the mesh will come out of the water, when you can remove it and take off the things on it.

Here is a picture of it when it is put together:

http://i289.photobucket.com/albums/ll219/amariah118/Inventors%20Club%20Competition/IMG_7365.jpg



And here is a picture of how the 3/4 in. pipes will slide over the 1/2 in. pipes

http://i289.photobucket.com/albums/ll219/amariah118/Inventors%20Club%20Competition/IMG_7364.jpg


I hope that made sense, and if you have questions, I am happy to answer. There are some improvements that I can already think of.

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.

What will grow on our substrates?

Everything will grow on our substrates!

The study of encrustations, biofilms, periphtyon, aufwucs and colonization is as complex and detailed as any in ecology.

We won't learn everything about this topic, but we can learn enough to be ready to deal with whatever we find on our aquamats, pvc poles, oyster strings or whatever other material we set out in the effluent canals.

Here's what a PVC pole looks like after just a few days in an effluent canal (this one was deployed in an estuary just downstream of the canals).

You can see the light brown glaze. That color indicates that the organisms growing here are probably mostly diatoms, a nutritious food that invertebrates love to eat.

Within about 3-6 weeks, the biomass on that pole will reach a "steady state" to which little biomass can be added. The total biomass of organisms will remain about the same from that point forward.

The same sized pole after 3 months in the water looks something like this....

The diatoms and the other nutritious diet items are still on the pole, but they have been joined by a wide variety of other organisms. The heavy lumps are barnacles. The dark green color comes mostly from blue green algae. Neither of those are desireable as food (although they may have other uses). Also colonizing the pole was a variety of worms, crabs and fishes (very small gobies were living inside some of the dead barnacle). Eggs of some organisms might also be attached.

Here are some questions for our groups to consider.

1. How can we minimize the amount of harmful or competing organisms entering the ponds from the substrates (some organisms like crabs and fish are already in the ponds because they enter the ponds as eggs from the pump, but we should still probably think about how to minimize the things we don't want).
2. How do we move large volumes of material off the substrates cheaply and without releasing the colonizing material back into the effluent canals?
3. How much time should these substrates sit before they are "harvested"?
4. What kind of data would we need to make these decisions scientifically?

Based on some coarse calculations, it seems we should be able to acheive significant reductions in the amount of nitrogen exiting the effluent canals (although I do need to correct an earlier assertion, apparently there are 30,000 Aquamats available, not 100,000).

Here's a link to a source that will tell you quite a bit about algae growing on attached surfaces. It may be useful to us here.