AVALIAÇÃO DO PH E UMIDADE RESULTANTE DA COMPOSTAGEM DE LODO DE ESGOTO ASSOCIADA COM DIFERENTES RESÍDUOS

Abstract

Composting is a technique for recycling organic waste from agro-industries, it reduces environmental impacts and adds improvements to the environment. Composting generates organic mixtures that are used as fertilizers for agricultural purposes. However, care must be taken with the destination of the waste to the soil as a source of nutrients and organic matter. The objective of this work was to evaluate the pH and moisture variation of dairy sludge resulting from composting combined with different residues. The experiment was conducted with the composting process combining four types of dairy waste (sewage sludge, cattle manure, grass pruning remains and boiler ash). The amount of residues were determined from moisture content and total nitrogen and carbon concentrations. The evaluated treatments consisted of pure sewage sludge (T1) and mixtures of sludge with other residues, being (T2) sludge + manure; (T3) sludge + ash; (T4) sludge + gram; (T5) sludge + gram + ash; (T6) sludge + dung + ash and (T7) sludge + grass + dung + ash. A randomized factorial arrangement was used, with seven treatments and three repetitions. Composting has proven to be an efficient method for treating sludge produced in a dairy effluent treatment plant, producing high quality fertilizers. The addition of grass pruning remains to the sewage sludge (Treatment 4) in the composting process provided adequate pH and moisture content.