NEW VERSATILE CONVERSION TECHNOLOGY FOR WET WHITE WASTE TRANSFORMATION TO

BIOFERTILISERSGabriel Zainescu1, Dana Corina Deselnicu1, Ioannis Ioannidis1, Marian Crudu1, Petre Voicu2

1 National R&D Institute for Textile and Leather – Division: Leather and Footwear Research Institute, 93 Ion Minulescu str., 031215, Bucharest, Romania, email: icpi@icpi.ro

2 Research Institute for Soil Science and Agrochemistry, 61 Marasti Blvd., 71331, Bucharest, Romania

A large number of tanneries and leather product manufacturers are facing serious problems regarding waste disposal, the more so as their storage in landfills leads to negative effects on the ecosystem. Using tanned waste is of particular interest because it offers the opportunity to eliminate all wastes from tanning, while obtaining qualitatively and economically valuable products. Organic biopolymers represent a source of raw material for agriculture, because the composition of protean wastes provides enough elements to improve composition and rehabilitation of degraded soils, and plants can capitalize some elements: nitrogen, calcium, magnesium, sodium, potassium, titanium etc. The wastes used for this innovative procedure for obtaining biopolymers, are obtained from wet white tanned leather through a new technique based on Ti-Al tanning agents. The work presents a new pilot technology for biochemical decay of the tannery protein wastes and use of the resulted products as fertilizers.

Facility for processing wet white wastes

A new method of treating wet white wastes was suggested, namely by wet white wastes hydrolysis in 2 steps, obtaining a protean biopolymer which, in combination with other polymers (polyacrylamide, acrylic, maleic, cellulose, starch etc.) will be used in agriculture.

These leather wastes were treated by chemical-enzymatic hydrolysis. Thus, a quantity of wet white leather wastes containing titanium was weighed, then mixed with water (200-500%) and subjected to a pretreatment by adding 10% CaO or 10% MgO for 4-6 h The mixture is hydrolysed in a 50 l autoclave with double jacket and stirrer, adding K2HPO4 at a temperature of 90-98°C for 2.5-5 hours. Then, the titanium containing hydrolysate is passed through a sieve with a mesh of about 0.5-1 mm2. Two parts are thus obtained, a liquid part that has passed through the sieve and an unhydrolysed solid part called “titanium containing sludge”, about 4-9% of the original waste subjected to hydrolysis. The liquid hydrolysate is dried and used as a fertilizer in agriculture.

The hidrolysis of wet white wastes

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The hydrolysis of wet white wastes

The second stage can be carried out, weighing wet white leather waste (containing titanium) and “titanium containing sludge” in proportion of 1:1 and subjecting it to a pretreatment in water (200-500%) and 1:2 MgO with NaOH at room temperature for 4-6 hours. This pretreatment step is required to obtain optimum pH for enzymatic digestion. Then 0.5-1% commercial enzymatic product K or D containing 30,000 MWU lipase, 900 units/g cellulase, 1.200 unit/g amylase and 10,000 units/g protease are added.The mixture is maintained for 1.5-2.5 hours at 35-40°C.

One-step hydrolysisT 90-98°C

for 2,5 - 5 h

Basification agents

( CaO or MgO)

Pretreatment Water 200-500%

for 4-6 h

Enhancing agents(K2HPO4)

Pelt

Two-step hydrolysis(enzymatic hydrolysis)0,5 - 1% commercial enzymatic product Time 1,5- 2,5 hours

Temperature 35-40°C

Methyl methacrylate

Leather finishing agent

Basification agents( MgO ) Polypeptide

s

Leather retanning agent

Acrylic acid monomer Modified paraffin

FERTILIZERSFOR AGRICULTURE

10-20% + Polymers

Technological process of obtaining protean biopolymer – biofertiliser from Ti-containing wet white wastesFT/IR-ATR spectra of biofertiliser samples

AcknowledgementsThis work was performed within the framework of the project INNOVA-LEATHER: "Innovative technologies for leather sector

increasing technological competitiveness by RDI, quality of life and environmental protection" contract POS CCE-AXA 2-0 2.1.2 no. 242/20.09.2010 ID 638 COD SMIS -CSNR12579, financed by the European Fund for Regional Development and the Romanian

Government in the framework of Sectoral Operational Programme Increase of Economic Competitiveness.