Alternative culture methods

Sustainable aquaculture series - episode 4

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Sustainable aquaculture series – episode 4: alternative culture methods

Welcome back to Calix Sustainable aquaculture series.

We hope you enjoyed our first 3 episodes, and it is great to have you back for more! In this series of videos, we explore different aspects of aquaculture and define key characteristics of a more sustainable approach to aquaculture.

Sustainable aquaculture is possible, with the right mindset, and innovative technologies.

Sustainable aquaculture series – Episode 3: Effects of disease

Welcome to the third episode of our Calix SUSTAINABLE AQUACULTURE SERIES

We hope you enjoyed our first two episodes and it is a pleasure to have you back!

In this series, we explore different aspects of aquaculture and define key characteristics of a more sustainable approach to aquaculture.

Aquaculture is replacing capture fisheries in supplying the world with dietary protein.

Let’s look more closely at the rapid and global proliferation of disease as a major threat to aquaculture production, and dive deeper into the conditions that can increase the spread of disease within ponds, and explain how it can affect our environment.

Finally, we’ll explore a few of the solutions available, to help control and manage disease in aquaculture.

Sustainable aquaculture series – Episode 2: Effects of shrimp culture on the environment

Welcome to the second episode of our Calix SUSTAINABLE AQUACULTURE SERIES

We hope you enjoyed our first episode – https://youtu.be/DKu2rUmvK6M – and it is a pleasure to have you back!

In this series, we explore different aspects of aquaculture and define key characteristics of a more sustainable approach to aquaculture. As we saw in episode 1, the increase in food production from aquaculture led to the introduction of intensive farming methods in shrimp culture.

Intensive shrimp farming practices have been adopted worldwide and developed very rapidly, increasing shrimp production, but also waste management challenges. Nowadays, all intensive shrimp ponds have issues with bottom sludge formation, which has direct effect on both yield and the environment. Management of waste water and pond waste (called “sludge”) are critical for all shrimp culture ponds.

Sustainable aquaculture series – Episode 1: Introduction to current shrimp culture

In this series, we will explore different aspects of aquaculture and define key characteristics of a more sustainable approach to aquaculture.

Aquaculture is projected to be the prime source of seafood by 2030, as demand grows from the global middle class and wild capture fisheries approach their maximum take.

When practiced responsibly, fish and shrimp farming can help provide livelihoods and feed a growing global population that is estimated to reach 9 billion by 2050.

In the past, we have made a lot of environmental mistakes on land, and as we increase our focus on fish farming, we are presented with an opportunity to not make those mistakes again – in our relatively untouched oceans.

But for an aquaculture system to be truly sustainable, there are a few things to be considered.

In this first episode, we will look at various aspects of shrimp culture, and at how it affects the environment.

pH & Alkalinity – How are they related?

A primer on the relationship between the bicarbonate system & pH

The relationship between pH & alkalinity is intimately connected with the chemistry of the aqueous bicarbonate equilibrium system.  An understanding of this will help us to communicate with & understands our customer’s needs.

CO2 +   H2O     <=>     CO2(aq)    <=>     H2CO3        <=>         H+             +              HCO3

                                                                                                   Carbonic acid        Hydrogen ion              Bicarbonate ion

Where <=>  represents a partial (equilibrium) reaction or dissociation

For H2CO3 dissociation constant, ka  = [H+].[HCO3]/[H2CO3]   is a measure of how much it dissociates as a function of [H+] concentration or pH

[H+]         = concentration of H+

[HCO3]  = concentration of bicarbonate ion (alkalinity)

[H2CO3] = concentration of carbonic acid (incl. dissolved CO2)

 

Taking log of both sides   =>  log10ka = log10[H+] + log10{[HCO3]/[H2CO3]}

Reorganizing               -log10[H+] = -log10ka   + log10{[HCO3]/[H2CO3]

And by definition         pH = constant + log10{alkalinity/(carbonic acid+ dissolved CO2)}

Slurry chemistry podcast – ACTI-Mag Magnesium Hydroxide’s reactivity in wastewater treatment

In this conversation between Ralph and Mark, we learn why Magnesium Hydroxide’s neutralisation rate depends on how readily the solids dissolve to form an alkaline solution; and why surface area can make a big difference.

ACTI-Mag is produced with Calix’s own highly reactive Magnesium Oxide (MgO) produced using Calix Flash calcination process. This short contact heat treatment (less than 10 sec) rapidly converts the Magnesium carbonate ore (MgCO3) to MgO by driving off CO2. As the CO2 is ‘fizzled-off’ from the fine ground mineral particles, it produces a highly porous mineral ‘honeycomb’ leaving a very high surface area.

This allows for rapid hydration to MHL and the resultant high surface, reactive ACTI-Mag product is more readily released by dissolution to allow a significantly higher rate neutralisation than other low surface area, low reactivity MHL products.

Safety of common alkalis for wastewater treatment

Hazardous chemicals can pose a significant risk to health and safety if not managed correctly. Municipal and industrial plant managers have specific duties under increasingly stringent health and safety regulations to manage risks associated with using, handling, and storing hazardous chemicals.

Being a plant manager at a wastewater treatment plant is an enormous responsibility as you answer to many high authorities such as the Environmental Protection Agency (EPA) or Occupational Health and Safety Administration (OSHA) in the US, and WorkSafe in Australia.

In this article, we’ve compared three common alkalis for wastewater treatment, and explained why magnesium hydroxide products are the safest and most cost-effective options.

  1. Ca(OH)2 -> Calcium Hydroxide, lime slurry, hydrated lime
  2. NaOH -> Sodium Hydroxide, caustic soda
  3. Mg(OH)2 -> Magnesium Hydroxide, milk of magnesia

There are laws in each state or territory that set out the requirements for handling and transporting dangerous goods. Switching to safer chemical products mean you are not only protecting the health and safety of your people, but you are making cost savings for years to come.

Caustic soda replacement at a fruit processing plant

ACTI-Mag for Chemical dosing units

ACTI-Mag for Biogas management

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