METHOD FOR PRODUCING FOLIAR FERTILISER FROM ENRICHED HAEMODIALYSIS FILTRATE AND ITS PRODUCT

The invention relates to the preparation of a solution for fertilisation purposes. The solution is prepared by mixing haemodialysis filtrate and ash, in our example, obtained from burning wood from orange, Pawlonia Elongata and olives trees. The use of this solution as a fertiliser offers advantages over other fertilising methods because it promotes the reuse of haemodialysis filtrate and ash from the burning of tree branches (in the specific proposal, from Pawlonia Elongata, orange and olive trees) to replace industrial fertilisers. We therefore propose an ecologically-friendly fertiliser for use in both the agricultural sector and in haemodialysis services. At the same time, there are economic benefits for crops. These benefits will be analysed after the results are presented.

This fertiliser preparation has a liquid form. Its exact method of preparation is as follows:

We collect, for example, in a 5 L plastic container the filtrate from the first hour of dialysis. The composition of the filtrate was averaged by taking samples from different haemodialysis machines as follows:

urea 3.5 g/L, potassium 0.1 g/L, sodium 32.66 g/L, phosphorus 0.11 g/L, calcium 0.7 g/L.

Approximately 1:10 w/w of ash is added in the filtrate, resulting from the burning of branches collected from the pruning of orange, Pawlonia Elongatas and olive trees. The filtrate is then diluted at a 1:5 ratio. This dilution was chosen to reduce the salt ratio. It remains for 72 hours in the container to absorb all elements of the ash, to ensure the elimination of any remaining microbes and to become absolutely safe for the environment. After 72 hours, the filtrate is filtered with a fabric filter to ensure it has no insoluble elements and is ready for use.

Calculation of solution - fertiliser contents

The solution's fertilising elements include the organic element urea and the macroelements potassium, phosphorus and calcium. According to the applicable fertilisation specifications, orange trees are fertilised by fertilising the soil with granular compound fertilisers in solid form, either via watering (fertigation) or via foliar sprays (foliar fertilisation is considered 8-10 times more effective).

Soil was sampled from the cultivation area for analysis (in February). The samples were received from many points, at the same depth, with the same homogeneity, and were mixed thoroughly to achieve the analysis sample.

The analysis results were as follows:

From our orange grove, we selected 8 healthy trees, about 35 years old, with the same water supply and lighting conditions. 4 of these were used as a control group and the other 4 as the experimental model group for foliar spraying with the prepared solution. A motorised spraying machine was used for spraying, providing good external and internal coverage of all foliage of the trees. The spraying was carried out with good coverage of the tree foliage from the bottom surface (as this is where the stomata are more numerous) in the morning hours (when the leaf stomata are open) with 20L of final product, i.e. with 5L of final product/tree. A total of 3 foliar sprays were carried out, one in March 2017 before flowering, one in May after flowering and one in September two months before harvest (in total, 3 times with 5 L/tree each time). The control trees were fertilised with standard NPK 15-15- 15 soil fertiliser. At the December harvest, the crop from each tree was distributed equally in identical boxes. Twelve boxes from each category (control and experimental groups) were then randomly selected and underwent statistical analysis with the following results:

Results

The statistical analysis was conducted by an independent statistician of the University of Patras. The results are listed below.

t-test: 0.038, Satterthwaite-Welch-t-test: 0.0386, Anova-F-test: 0.0384, confirming the assumption that the trees in the experimental group produced heavier crops.

The replacement of industrial fertilisers with this fertiliser, made from reusing the above materials, was based on the idea that urea has been used as a fertiliser in the form of urine since antiquity, so we thought of using it in the form of a modern substitute. Our method offers the following advantages:

1. Economic advantage of the proposed method, estimated at 5 euros per tree/year, over the industrial fertiliser, (zero cost for our own method as all materials used are recycled) compared to a cost of 5 euros per tree/year using industrial fertilisers for the rest of the crop. Fertilisation accounts for 60% of total crop costs (the rest includes labour and water supply). This means cost savings of 60% on total crop costs. According to Eurostat Statistics Explained, there are about 60,000,000 citrus trees in Europe. Thus, according to the above data, the profit from using this fertiliser reaches 300,000,000 euro per year, if all trees used a fertiliser like the one proposed. Obviously, this fertiliser can be used for any plant with nitrogen and potassium needs and relative resistance to sodium. Orange cultivation was used as an example because we own an orange grove. Of course, on a large scale, the costs of transporting the filtrate should be taken into account. The required timber for ash production is easily ensured by the pruning of trees from the same plantation, resulting in a vertical production (this happened in our case because we own 1000 orange and 2000 pawloniae trees).

. Water savings. Based on US literature, 50 million haemodialysis sessions are carried out each year in 5,000 haemodialysis centres (representing 26% of all haemodialysis centres), consuming 5 trillion litres of water per year (data for 2007). In Australia, 400 million litres (about 400 Olympic-size pools) evaporate during the drought period yearly. In Morocco, water consumption for haemodialysis treatments reaches 190 million litres of water per year. In conclusion, due to the extensive loss of water in haemodialysis treatment, haemodialysis centres should focus on water savings. Our proposal, in view of the above, uses dialysis filtrate, which would otherwise be discharged, as a fertiliser and as a dilution agent for the production of our fertiliser.

. Ecological advantage, due to the reduction of water and soil contamination by the industrial fertilisers it replaces. Advantage for users, as obtaining the required amount of dialysis filtrate is easier than in alternative fertilisation methods proposed in the past, concerning the use of corresponding amounts of human urine.

Additionally, foliar spraying is superior to irrigating with the same solution. When using a standard commercial fertiliser (granular or foliar) containing urea, each tree receives 2 kg, with 40% urea content, i.e. 800 g of urea per tree. This fertiliser is sprayed only once. If we used our fertiliser for fertigation, we should divide it into three doses, every 15 days. This means we should pour 265 g of urea at a time, diluted to a volume of 75 litres per tree at a time, compared to only 5 litres in the case of a foliar fertiliser. At the same time, foliar fertilisation avoids excessive soil salinisation and helps reduce salt absorption by the tree, as the foliar absorption of cations through the epidermal cells decreases as follows: NH4 + > K+ > Na+ > Ca2+ > Mg2+