Reduction of the phenolic components in olive-mill wastewater by an enzymatic treatment and its impact on durum wheat (Triticum durum Desf.) germinability R. Casa a, * ,A.DÕAnnibale b , F. Pieruccetti a , S.R. Stazi b , G. Giovannozzi Sermanni b , B. Lo Cascio a a Dipartimento di Produzione Vegetale, Universit  a degli Studi della Tuscia, Via San Camillo de Lellis snc, Viterbo 01100, Italy b Dipartimento di Agrobiologia and Agrochimica, Universit  a della Tuscia, Via San Camillo de Lellis snc, Viterbo 01100, Italy Received 21 May 2002; received in revised form 22 October 2002; accepted 22 October 2002 Abstract Olive-mill wastewater (OMW), an effluent of olive oil extraction process, is annually produced in huge amounts in olive growing areas. An interesting option for its disposal is the spreading on agricultural land, pro- vided that phytotoxic effects are neutralized. The objective of the present investigation was to evaluate the potential of an enzyme-based treatment in removing OMW phytotoxicity. To this aim, germinability experiments on durum wheat(Triticum durum Desf.cv.Duilio)wereconductedinthepresenceofdifferentdilutionsofraworenzyme-treated OMW. OMWtreatmentwithlaccaseresultedina65%and86%reductionintotalphenolsand ortho-diphenolsrespectively, due their polymerization as revealed by size-exclusion chromatography. Raw OMW exerted a significant concentration-dependent inhibition on the germinability of durum wheat seeds which was evident up to a dilution rate of 1:8. Whentheeffluentwastreatedwithafungallaccase,germinabilitywasincreasedby57%ata1:8dilutionandby94% at a 1:2 dilution, as compared to the same dilutions using untreated OMW. The treatment with laccase also decreased the mean germination time by about 1 day as compared to untreated controls. These results show that germinability inhibition due to OMW can be reduced effectively using fungal laccase, suggesting that phenols are the main determinants of its phytotoxicity. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Laccase; Wastewater; Phytotoxicity; Germination; Wheat 1. Introduction Olive-mill wastewater (OMW) is a by-product of the olive oil extraction process. Around 30 million m 3 of OMWareproducedannuallyintheMediterraneanarea, causing environmental concern. The disposal of this wasteisregulatedaccordingtoguidelinesandstandards aimed at evaluating the quality of industrial wastewater in view of the safeguard of aquatic ecosystems (Tomati, 2001).AvalidalternativetothedischargeofOMWinto water bodies is the spreading on the land. In Italy, the legislation provides guidelines for OMW disposal on agricultural soils and recently a special permission al- lows the land spreading of this waste also in Portugal. However this practice is performed illegally in several Chemosphere 50 (2003) 959–966 www.elsevier.com/locate/chemosphere * Corresponding author. Tel.: +39-0761-357559; fax: +39- 0761-357558. E-mail address: rcasa@unitus.it (R. Casa). 0045-6535/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0045-6535(02)00707-5