Aquaponics: A Solution To China’s Water Crisis.

China is undergoing the worst water crisis in its history.  In northern China, the fossil water supplies (ancient underground aquifers that cannot be resupplied by rainfall) are already mostly used up. However, the solutions being employed to date seem to be just a finger stuck in the dyke of this water crisis problem, given the magnitude of the shortfall and the rate of increase of demand for water in China.  Food production and China’s industrial revolution are fuelling ever more extravagant water use. Here are some mind boggling China water crisis statistics from the experts:

‘China becomes drier each year—its freshwater reserves declined 13% between 2000 and 2009. Severe droughts occurred in 2000, 2007 and 2009. Normally the southern regions receive 80% of China’s rainfall and snowmelt, about 79 inches a year, while the north and west get 20%, 8 to 16 inches.

This winter, Beijing and the northern and eastern provinces had the worst drought in 60 years. It has left 2.57 million people and 2.79 million heads of livestock short of water, and affected 12.75 million acres of wheat fields, which sent global food prices soaring. South China experienced 50% less rainfall than normal, resulting in the drying up of rivers and reservoirs. While torrential rainfall fell on the south this week, northern regions are still suffering from drought.

China’s per capita availability of water is 1/3 the world’s average, and in the dry north where most of the grain and vegetables are grown, per capita availability is only 1/4 of that in the south. Over 300 million people in rural areas have no access to safe drinking water and 54% of China’s main rivers contain water unfit for human consumption.’ from ‘How China Is Dealing With Its Water Crisis’ by Renee Cho | – Blogs of the Earth Institute, Columbia University, 2011.

The wastage of water by conventional agriculture and industry in China does not only threaten China, but the world at large. What would happen if China, which has billions of inhabitants, should competely run out of water?  Where would all these people go and how could this water supply shortfall be made up?  How can China improve its water use efficiency?

The Chinese government is spending billions of yuan on ambitious schemes such as desalination plants to turn seawater into fresh water, and a huge canal project to take water from South China to North China to alleviate the drought there.  However these projects do not really focus on water use efficiency.  They are not designed to save water, only to provide more water from other areas which seem to have a more plentiful supply. The people of South China are already concerned that North China may soak up too much of their finite water supply via the new canal, and desalination projects have a problem: what do you do with the mountains of salt that result from boiling off all that H2O?  China needs more water to ensure food production. Or does it?

Meanwhile water use in China is increasing exponentially as its booming economy ups the demand for water-intensive farmed products such as meat. Industry also uses and pollutes mind boggling quantitities of water every day.

Meanwhile, there is a solution to the extravagant water use in China’s agriculture.  This water use efficiency solution is largely being ignored, despite the latest policy moves on the part of China’s central government to encourage new cutting-edge agriculture techniques and food production technologies . This proven water efficient and water saving agriculture technology has been in existence and proven to work in different climates and cultures at least since the 1970s, and it does not rely on expensive biotech, chemical fertilizers, or complicated widgets to work.

It is called modern, up to date water-saving water-efficient aquaponics and it is an upgrade on conventional aquaculture, which is already practiced all over China.  It marries aquaculture to aquaponics and in so doing saves 90% or more of the water required to grow food:

‘The aquaculture industry largely has developed without regard to the increasing scarcity of water. Traditional intensive (high production per unit area) aquaculture systems require more water than less intensive

pond systems, being dependent on high volumes of fresh water flowing through fish-rearing tanks to supply dissolved oxygen and remove deleterious metabolites. Both= have very high water demand compared with other competing industries, arguing strongly for the integration of aquaculture with other industries or with agriculture (Phillips et al. 1991).

Integration of aquaculture with agriculture can reduce the water requirement for the production of quality protein and fresh vegetable products relative to both culture systems operated independently. Innovative fish/vegetable co-culture systems use the nutrient by-products of fish culture as direct inputs for vegetable production, constantly recycling the same water. While pond or cage aquaculture in arid environments is limited by the constraints of water supply and soil type, recirculating systems are unaffected

by soil type, use less than 1% of the water required by pond culture for the same yields and are efficient in terms of and utilization (Rakocy 1989) like the high-volume, flow-through systems….

The purpose of this work was to design and test a recirculating fish/vegetable coculture system with high efficiency of water use in production of quality food as well as high functional and technological simplicity.

The main features were a greatly increased hydroponic plant culture biofilter capacity relative to the fish rearing capacity compared with previous systems (Rakocy and Hargreaves 1993); also, the fish effluent, including solids, was pumped directly onto sand beds. The sand beds served as:

    1. biofilters operating in the reciprocatingmode;

    2. hydroponic plant growth substrate; and

    3. the locus for oxidation of organic solids.

We have examined the water quality and general dynamics of the system as a function of the ratio of plant growth/ biofilter capacity to fish rearing capacity (McMurtry et al. 1997). In this paper we consider the effects of these four ratios of biofilter volume (BFV) to fish rearing tank volume (0.67/1, 1.00/1, 1.50/1 and 2.25/1) on the efficiency of water use in production of protein and food calories, and on the economic productivity of the system.

Abstract.-Fish and vegetable production were linked in a recirculating water system designed to achieve a high degree of efficiency of water use for

food production in addition to functional and technological simplicity. Hybrid tilapia Oreochromis mossambicus X O. niloticus L. were grown in tanks associated with biofilters (sand beds) in which tomatoes Lycopersicon esculentum were grown. The effect of four biofilter volume (BFV)/fish rearing tank volume ratios (0.67/1, 1.00/1, 1.50/1,2.25/1) on water use efficiency

was evaluated. ‘Laura’ (first experiment) or Kewalo’ tomatoes were grown 41m2 in biofilters of four different sizes and surface-irrigated 8 times daily with water from the associated fish tanks. Daily water consumption increased with BFV/tank ratios and with time. Fish production rates increased with biofilter volume in the first experiment, but were not significantly different in the second experiment. Total tomato fruit yield per plot increased from 13.7 to 31.7 kg (Experiment 1) and from 19.9 to 33.1 kg (Experiment 2) with increasing BFVItank ratio. For fish plus fruit, total energy production increased from 4,950 to 8,963 kcaU plot and from 4,804 to 7,424 kcallplot in Experiments 1 and 2, respectively, and protein production increased from 536 to 794 and from 352 to 483 g/plot in Experiments 1 and 2, respectively, with increasing BFVI tank ratio. Trends in water use efficiency for production of food energy (kcal/L) and of protein (g/L) in tomatoes and fish were complex. Water use efficiency for total energy production (fish plus fruit) did not significantly differ with biofilter volume. Economy of water use for total protein production (fish plus fruit) decreased significantly with increasing BFV/tank ratio. The component ratios of the system may be manipulated to favor fish or vegetable production according to local market trends or dietary needs, and thus may have economic potential in areas of limited water supply and high dand for quality food.’

From ‘Efficiency of Water Use of An Integrated Fish-Vegetable Co-Culture System,’ JOURNAL OF THE WORLD AQUACULTURE SOCIETY Vol. 28, NO.4, December, 1997

(see the Download Library).

Since this was written many further advances have been made in making this technology, now called aquaponics, into a commercial and immensely water-efficient solution for areas with extreme and persistent water shortages. At the University of the Virgin Islands, where I was trained, their commercial aquaponic farm produces on average 5 metric tons of tilapia fish and at least that in vegetables (this varies depending on what is grown at the time). In a greenhouse, with vertical growing and the use of low energy grow lights, more biomass can be grown, but at the UVI, which is in the tropics, the system is outdoors.

The space taken up by the system covers only 1/8 of an acre (1/16 of a hectare).

This food is grown using 1.5% of the water normally required to produce that volume of food on that acreage. The UVI is in a Caribbean archipelago which is chronically short of water and arable land, so the whole system was developed to use MINIMAL QUANTITIES OF WATER.

It is a recirculating aquaculture and hydroponic system that recycles the water volume in which tilapia fish and plants live constantly throughout the system.

A clarifying unit removes the fish solids via a flushing procedure. This effluent is put into settlement ponds and dewatered, and the resulting fertile water and fish manure are used on field crops as irrigation water and organic fertilizer.

In the context of China’s water shortage, such units could be manufactured in bulk and rolled out to farmers all over the country with training in how to use them properly. This training is short, but very necessary since the techniques are not the same as conventional farming and require at least a high school level of scientific understanding to be effectively used. Otherwise systems will be deployed only to be abandoned as non-functional because their operatives do not understand how to use them in a water-efficient and food productive manner.

Aquaponics is a skill China desperately needs to save untold amounts of water and to ensure its future food supply.  Its water use efficiency in fish rearing and vegetable farming make it a form of sustainable food production which is in sharp contrast to the methods currently used to feed most of China’s teeming billiions. Ironically, the aquaponic system as currently designed is actually just a techical upgrade on the traditional methods of fish rearing in rice paddies that were used in ancient China before the advent of artificial fertilizers and pesticides, which killed off this fish rearing practice since these artificial chemicals kill the fish.  Artificial fertilizers are not necessary in an aquaponaic system, they kill the fish, and the fish waste is what feeds the plants in the hydroponic part of an aquaponic system.  All chemical pesticides, even the ‘organic’ pyrethrin-based ones, kill the fish as well.  You can only use modern organic biological pest control, such as friendly insects and bacteria, to control pests in aquaponics.  However, this works very well and means that crops can be harvested soon after being treated for pests, unlike crops treated with toxic pesticides.  This is sustainable food production with a very small environmental footprint, eminently suitable as a large part of the soution to China’s water crisis.

At Aquaponics Global, we can help with selection of appropriate systems and methodologies, and also with the design and implementation of fast-track training courses and with training trainers on water-efficient aquaponic systems once they are in place.  There are also other greenhouse and recirculating aquaculture techniques such as biofloc tilapia aquaculture that also offer massive water savings in China’s water crisis at low cost and with fast roll-out times compared to more high-tech engineering water crisis solutions.
I also recommend the following books to anyone seriously considering setting up an aquaponic farm of any size:

 

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