Acute Toxicity of Olive Mill Wastewaters from the Gaza Strip to Four Marine Invertebrates Acute Toxicity of Olive Mill Wastewaters from the Gaza Strip to Four Marine Invertebrates

Abstract

: Background: The Olive Mill Wastewater (OMW) that results from olive oil production processes, is a potential toxic pollutant, adversely affecting the fauna of aquatic ecosystem. Due to the absence of implementation of stringent rules and regulations to control the disposal of industrial wastewaters into the environment, most of the wastewaters generated from the different olive mills in the Gaza Strip are usually discharged into sewer systems or into Wadi Gaza which finally reach the Mediterranean Sea. Objective: The present study aims to evaluate the acute toxicity of OMW to four marine invertebrates; Artemia salina, Balanus amphitrite, Brachionus plicatilis and Mytilus sp.. Materials and methods: Composite samples of OMW were collected from an olive mill near Gaza City and the physicochemical characteristics such as pH, EC, BOD, COD and total nitrogen were analyzed. The test organisms were exposed to four concentrations of OMW, 1.25, 2.5, 5 and 10% (v/v) under static conditions. Mortality data were recorded after 24 h and analyzed using U.S. EPA Probit analysis software to calculate LC50 values. Results: The results of the physicochemical characteristics of OMWs were found to fall within the range of the reported literature data. In the terms of median lethal concentration (LC50), the order of sensitivity of tested organisms was B. plicatilis > A. salina > Mytilus sp.> B. amphitrite with estimated LC50 values of 3.3%, 5.1%; 6.5% and 7.1% (v/v) respectively. Based on derived 24h LC50 values, OMW appears to be highly toxic to tested organisms with acute toxicity units (ATUs) ranged from 14 to 30. The safe dischargeable concentration of OMW was found to be very low i.e. ? 0.710% (v/v). Conclusion: Results indicated that OMW is highly toxic to marine invertebrates and may pose relatively serious hazards to receiving waters; accordingly, it should be treated before disposing to aquatic environments. Keywords: Olive mill wastewaters, Acute toxicity, Marine invertebrates, Gaza Strip.