https://www.nature.com/articles/s41545-018-0027-5

• Article
• Open Access
• Published: 01 February 2019

Virus and bacteria inactivation by CO2 bubbles in solution

• Adrian Garrido Sanchis, 
• Richard Pashley & 
• Barry Ninham 

npj Clean Water volume 2, Article number: 5 (2019) Cite this article

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Abstract

The availability of clean water is a major problem facing the world. In particular, the cost and destruction caused by viruses in water remains an unresolved challenge and poses a major limitation on the use of recycled water. Here, we develop an environmentally friendly technology for sterilising water. The technology bubbles heated un-pressurised carbon dioxide or exhaust gases through wastewater in a bubble column, effectively destroying both bacteria and viruses. The process is extremely cost effective, with no concerning by-products, and has already been successfully scaled-up industrially.

Introduction

Wastewater usually contains human enteric viruses like hepatitis and rotavirus and bacteria like Escherichia coli. If this water is to be reused it has to be disinfected. Collivignarelli et al.1 found that ultraviolet (UV) irradiation and chemical treatments using chlorine, chlorine dioxide, peracetic acid or ozone were the most used technologies for wastewater disinfection. However, all these water disinfection technologies have limitations. For example, chlorine and chlorine dioxide react with organic compounds and form reactive chlorinated organic compounds that are hazardous to humans. In addition, chlorine needs at least 30 min contact time and is not able to eliminate Cryptosporidium. Chlorine dioxide has high management costs and is very unstable. Other disinfection methods such as ozone and UV irradiation are complex to operate and maintain. Rotavirus can be resistant to UV treatments and its efficiency is affected by the dissolved organic and inorganics in the wastewater, as well as its colour and turbidity.2 Paracetic acid increases chemical oxygen demand (COD) and biochemical oxygen demand (BOD) due to the formation of acetic acid.1 Therefore, a major challenge exists to develop new, energy-efficient technologies to address these problems.

Here we report on one such candidate technology for sterilisation that seems to do the job. It uses atmospheric pressure bubbles of CO2 in a new device (ABCD). If this process successfully inactivates MS2 virus (ATCC15597-B1) and E. coli C-3000 (ATCC15597), that are surrogates for enteric pathogens, then this technology will be able to inactivate real waterborne viruses and bacteria for water reuse without the need for (high energy) boiling.

In preceding work3,4 we conducted different experiments where the bubble diameter of 1–3 mm was measured using high speed cameras. An earlier variant we called the hot bubble column evaporator (HBCE) process.5,6,7 It used hot air bubbles of 1–3 mm diameter and was operated in the temperature range of 150–250 °C. The bubbles transferred heat to surrounding water and thermally inactivated dispersed viruses and bacterial cells. At the same time, low, steady-state solution temperatures in the range of 42–55 °C were maintained.8 An instantaneous transient hot surface layer must also form around the rising, initially hot, air bubbles. The inactivation process clearly involves collisions of bacteria or viruses with the hot air bubbles5,6 and the surrounding heated layers.7 Other gases (air, N2, O2 and Argon) achieved similar inactivation results, at 200 °C inlet gas temperatures for viruses and at 150 °C for bacteria.9 However, CO2 gas, at the same inlet gas temperature, is far superior with much higher inactivation rates at lower temperatures than with other gases.9 Hence, we here embark on a more thorough study of the effects of CO2 bubbling on viral and bacterial inactivation in pure sodium chloride solutions, using the HBCE device at atmospheric pressure with the acronym ABCD.

Many waste disposal industries like landfills, bio-gas plants and coal power plants emit large amounts of CO2. Hence, the potential use of CO2 bubbles in water treatment processes to sterilise water at atmospheric pressure offers an attractive new technology at the very least. Earlier we showed9 too that the heat generated in exhaust combustion gases that contain CO2 can also be used to increase the performance of this new sterilisation treatment. That we will also take further.

The process is very different to others that involve CO2. Thus, many authors10 have shown that pressurised CO2 in a range of 5 to 1000 atm can achieve viral and bacterial inactivation.

High-pressure carbon dioxide has been proposed as a cold pasteurisation alternative for more than 25 years.11 The new ABCD reactor, described here, achieves equivalent or better results but without the need for pressurisation, i.e., at just 1 atm. The process has been patented by the University of New South Wales as Australian Patent Application No. 2017904797.

A Better Bug for Biofuels

From: Technology Review

 Scientists are optimizing a lipid-producing microbe to make biofuels.

Glow bug: Scientists are engineering Rhodococcus bacteria to boost production of lipids (glowing white balls), which can be converted into biodiesel.  --->

While most attempts to engineer biofuel-producing microbes have focused on well-known organisms such as yeasts and E. coli, scientists also hope to co-opt the unique metabolic functions of some of the microbial world's less-studied creatures. Anthony Sinskey and his team at MIT have been cataloguing the genomic secrets of Rhodococcus bacteria, soil-dwelling microbes known to eat a variety of toxic compounds. The goal is to make a biodiesel-producing organism that can use a variety of sources as fuel. "We have done a lot of the basic chemistry and biology," says Sinskey. "Now we need to figure out how to maximize yields."

The strain of bacteria that Sinskey is working on, Rhodococcus opacus, is related to the type that causes tuberculosis, but it has two particularly appealing qualities. The bacteria have a flexible appetite, with the ability to eat a number of sugars and toxic compounds--in fact, the microbes were originally isolated from contaminated soil, where they were breaking down petroleum waste products. In addition, R. opacus are one of just a few types of bacteria that naturally produce a type of lipid called tryacylglycerols, which can be chemically converted into biodiesel. "Its life is focused around lipid metabolism, eating weird lipids and making more of them," says Jason Holder, a postdoctoral researcher in Sinskey's lab. "The trick is to engineer them to make it more efficiently, using waste streams of carbon."

The research is part of a larger effort to develop biofuels that, unlike ethanol made from corn or sugarcane, do not rely on food sources or agricultural land. Some companies, such as Synthetic Genomics, Amyris, LS9, and Joule Biotechnologies, are using synthetic biology techniques to engineer bacteria to more efficiently produce desirable metabolic products that can be used for biofuels.

Sinskey's team has recently sequenced R. opacus's genome and mapped its 9,000 genes into various metabolic pathways. Understanding these pathways allows scientists to boost or inhibit specific reactions, which can in turn increase the microbe's efficiency at creating a particular fuel or end product. The researchers have also developed a microarray for Rhodococcus--a genomics tool that allows scientists to quickly assess patterns of gene expression--and are using it to study these metabolicnetworks. "It will allow us to predict other bacteria that might do the same thing," says Sinskey, "and it will help us identify genes important in the assembly process." They plan to publish the genome soon.

The researchers have already created a strain of Rhodococcus that can eat a mix of two types of sugars, glucose and xylose. Once scientists have found a way to break down cellulosic biomass into simpler sugars, the ability to use more than one will simplify the production process. "They are not like wimpy E. coli that can't use different sugars simultaneously," says Sinskey. "These bacteria gobble them up." The researchers have also engineered strains that can feed on glycerol, which is a waste product in the production of biodiesel.

Sinskey and his team hope to develop better ways of isolating the lipids from bacteria at a commercial scale, perhaps via additional genetic engineering. For example, altering production of a specific protein encourages the lipids to aggregate into balls, called lipid bodies, which makes the molecules easier to recover. "Ideally, we want to develop a way to make the lipid body pop out of the cell," says Sinskey.

It's not yet clear how long it will take to create a process that is efficient enough for commercial production. "I don't think I'm far behind lots of companies that have lots of publicity in this area," says Sinskey. "I think in two to three years I will have a robust process."

Sinskey previously developed a way to make polymers from bacteria, founding a bioindustrial company called Metabolix in the early 1990s. A $300 million plant that will produce the company's biodegradable plastic is slated to begin operations later this year in December, as part of a joint venture with agricultural giant ADM.

high tech composites and plastic from plants

I see the possibility of making high tech bio-composite materials with natural fiber and binders replacing fiber glass or carbon fiber and petroleum based epoxy currently used to make high tech composites.

Plant based epoxy are already available on the market, but I think it's important to be able to bring such technology down to a crafts level where rural farmers in third world countries can produce high tech composite materials using nothing but plants and local materials.

• Jute also known as Burlap
• Hemp
• Kenaf
• Ramie one of the strongest natural fibers

For more read about Fiber Crops

There is also the possibility of ultra strong carbon fibers from plant based chemicals as well, replacing petroleum.

In the course of my research I found it is possible to get almost all of the compounds found in Crude Oil from organic sources such plant, animal waste and algae.
Using catalysts and heat and pressure known as pyrolysis it's possible to convert almost any source hydrocarbon in to almost any other. As computing power increases we will be able to have computational chemistry simulators that will be able to perform billions of experiments to find the right chemical processes to produce anything we are currently getting from petroleum today, including the gasoline we currently run are automobiles with today.


Epoxys and Plastics.

• Wiki: Biodegradable plastic 
• Wiki: Bioplastic
  
• Edmond firm sees future selling plant-based epoxies
• More plastic from plants
• Plastic That Grows On Trees

On the more technical side:

• Adhesive Properties of Wood-biomass Based Epoxy Resins
• Synthesis of wood-based epoxy resins and their mechanical and adhesive properties
• Epoxidized Mesua ferrea L. seed oil-based reactive diluent for BPA epoxy resin and their green nanocomposites

Another good link:
ECOS Magazine

UPDATE: 9/30/09
From:  A Better Bug for Biofuels
MIT Professor Anthony Sinskey developed a way to make polymers from bacteria, founding a bioindustrial company called Metabolix in the early 1990s. A $300 million plant that will produce the company's biodegradable plastic is slated to begin operations later this year in December, as part of a joint venture with agricultural giant ADM.