Composting winery wastes with clinoptilolite. Suitability for land application.

Soil application of raw winery wastes is a procedure of doubtful appropriateness, mainly because of waste properties, i.e. very acidic pH; high electrical conductivity; and high content of polyphenols. The disposal of winery waste on soils may cause various environmental and health hazards as for example soil overloading with polyphenols and salts, phytotoxicity to plants, odor nuisance etc. Pathogens, which may still be present in the decomposed material could spread plants and soil diseases, while waste piles attract insects, pests, domestic rodents and wildlife which may threaten public and animal health. Despite these facts, many wine producers discharge winery waste to the nearby agricultural or forest ecosystems, without treatment although this type of agricultural waste could be a significant source of organic matter and nutrients.

 

In general, degradation of winery waste is a slow procedure which becomes even slower under the xerothermic climatic conditions in Greece, which may slow down the microbially mediated decomposition of organic matter and nutrients cycling; degradation of winery waste piles takes more than 5 years to be completed naturally. However, the final products are of doubtful appropriateness for fertilization use, mainly because of low quality organic matter and low nutrients content (lost mainly due to the exposure of piles to uncontrolled environmental conditions for years).

 

This study aims to highlight the advantages of composting winery wastes by using also other agricultural wastes and additives as feedstock to produce a safe and environment friendly compost, appropriate for application to agricultural ecosystems. For this a 41 hectares vineyard in North Greece of about 400 tn grapes yield annually and generation of approximately 100 tn of waste was selected. Winery waste was collected after harvesting and wine-making period of 2018 and composted with cow manure, wheat straw and clinoptilolite up to 5%.

 

Composting phase lasted 5 months, and during this period the pile was monitored as regard temperature, moisture and oxygen content. After composting completion, the final product was fully characterized in terms of its physical and chemical properties, considering national legislation organic materials reuse on soils. The outcomes of this study show a great potential for managing such waste types by composting using clinoptilolite in the feedstock materials since the final product has suitable physical and chemical properties for many crops, i.e. slight alkaline pH, low electrical conductivity, low polyphenol content and high content of available nutrient, therefore can be used as soil amendment or organic fertilizer.