Evaluation of phytotoxicity effect of olive mill wastewater treated by different technologies on seed germination of barley (Hordeum vulgare L.)

Abstract

Olive-mill wastewater (OMW) is a by-product effluent of olive oil extraction process that is produced in large amount in the Mediterranean region. OMW is believed to induce phytotoxic effect on organisms including seed germination and plant growth. The objective of this study was to evaluate the impact of untreated and treated OMW with different techniques on seed germination of barley (Hordeum vulgare L.). The following treatments were investigated: (1) tap water (control); (2) OMW treated by aerobic biological technology in a Jacto Reactor (JR); (3) OMW treated by solar fenton oxidation (SFO); (4) OMW treated by microfiltration followed by nanofiltration (MF+NF); (5) OMW treated by microfiltration followed by reverse osmosis (MF+RO) process; (6) diluted OMW with tap water (25 % OMW); (7) diluted OMW with tap water (50 % OMW); (8) diluted OMW with tap water (75 % OMW); and (9) untreated OMW (100 % OMW). A germination test was conducted in an incubator at temperature of 23 (∘)C. In each petri dish, a filter paper was mounted and ten seeds of barley were placed on the filter paper. Five milliliter of water were added to each petri dish. The seed germination was determined by counting the number of germinated seeds to calculate the percentage of germination (G %). Germination rate index (GRI), seed vigor index (SVI), and phytotoxicity index (PI) were also calculated. Then, the dry weights and lengths of the shoots and the roots of the germinated seeds were measured. The results show that 100, 75, and 50 %OMW were very phytotoxic and completely prohibited seed germination. However, phytotoxicity decreased significantly following treatments of OMW with all techniques investigated and by the 25 % OMW dilution, as results of removing the phenols and other phytotoxic organic compounds from the OMW or by diluting it. This was evidenced by relative enhancement of the dry weights and lengths of shoot and root as well as the G %, GRI, SVG, and PI. It was concluded that if OMW will be used for irrigating crops, it has to be first treated or diluted with tap water at a ratio of 1:3 OMW:water at least. The most efficient treatment techniques in reducing the phytotoxicity of OMW were the MF+RO, followed by SFO and JR.

Effect of brewery wastewater obtained from different phases of treatment plant on seed germination of chickpea (Cicer arietinum), maize (Zea mays), and pigeon pea (Cajanus cajan)

“…Similar inhibitory effects of higher salt concentrations were expressed by Barazani and Golan-Goldhirsh (2009) on germination of Salsola inermis and by Khan et al (2017) on rice germination. Osmotic pressure and ion toxicity of salts present in brewery wastewater (RO reject) may be the reason for adverse effects on seed germination as stated by Rusan et al (2015) on barley germination by application of olive mill wastewater. Osmotic pressure due to higher salt concentration mainly shows effect on water uptake by seeds thus leading to inhibition/reduction of seed germination (Naeem et al 2015).…”

Annual spreading of olive mill wastewater over consecutive years: Effects on cultivated soils' physical properties

“…Yet, great concerns have been raised regarding the adverse effects of OMW on and to seed development and germination (Aliotta, Fiorentino, Oliva, & Temussi, 2002;Aviani, Raviv, Hadar, Saadi, & Laor, 2009;Barbera, Maucieri, Ioppolo, Milani, & Cavallaro, 2014;Boz et al, 2009;Buchmann, Felten, et al, 2015;El Hadrami et al, 2004;Rusan, Albalasmeh, Zuraiqi, & Bashabsheh, 2015;Saadi, Laor, Raviv, & Medina, 2007;Saadi et al, 2013). Still, following land application, only short-term phytotoxic effects were mostly observed, lasting a few weeks (Piotrowska, Iamarino, Rao, & Gianfreda, 2006;Saadi et al, 2007;Saadi et al, 2013), although Mekki, Dhouib, Feki, and Sayadi (2008) detected increased concentrations of phenolic compounds at a depth of 1.2 m in a sandy soil 4 months after application and extracted a moderately phytotoxic residual phenolic fraction from the upper soil layer 1 year after application.…”

Phytotoxicity, cytotoxicity and genotoxicity evaluation of organic and inorganic pollutants rich tannery wastewater from a Common Effluent Treatment Plant (CETP) in Unnao district, India using Vigna radiata and Allium cepa

“…Hence, treated wastewater was assessed for its phytotoxic and genotoxic nature. The seed germination test is considered as one of the simplest short-term, sensitive and cost effective method of phytotoxicity evaluation for wastewaters (Rusan et al, 2015;Lyu et al, 2018). Seed germination is a very sensitive process, likely to be disturbed by the substances present in the environment.…”