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In this study, chemical coagulation and electrocoagulation (CC/EC) were evaluated as alternatives for olive mill wastewater (OMW) treatment. Jar test was used to determine the most favorable dosage of coagulant, pH of the process and proper flocculation time. CC experiments were carried out using coagulants (alum, lime, ferric chloride and cement dust). Coagulation efficiency was evaluated by measuring chemical oxygen demand (COD), color and turbidity removal ratio. From Tukey test, it was established that alum was more efficient than other coagulants. The maximum removal efficiency of COD and turbidity were 42%, 66%, respectively. The optimum condition was achieved at 0.5 g/100 ml of alum, pH = 6 and flocculation time ranging between 15 min to 25 min. This study used aluminum plates as anode and cathode in electrocoagulation to study COD removal from OMW. Its performance was optimized using Box-Behnken experimental Design and Response Surface Methodology. The following EC optimal conditions were found: current density = 60 mA/cm 2 , pH = 4 and electrolysis time 20 min. At these conditions, the maximum COD removal ratio was 47% with an estimated operating cost of 1 USD/m 3 .

In areas without sewer collection infrastructure, decentralized treatment is regarded as being necessary to provide sewage management and sanitation. Organic matter can be degraded anaerobically with Up-flow Anaerobic Sludge Blanket (UASB) digesters resulting in biogas production that is used in a wide range of uses (i.e., for heating, electricity, and fuel). Under decentralized operations, traditional aerated wastewater treatment can be expensive and readily overloaded by high-strength effluent or changes in the environment's temperature. High-strength wastewater can be treated with UASB digesters, which can also produce biofuel and reduce the high costs of aeration. Operations can be stabilized and granule formation improved by adding supporting components such as microbial communities and biochar made from Phragmites Australis to the UASB. The first stage of this study statistically investigates the optimization of anaerobic treatment conditions of cattle wastewater in a batch study. In the second stage, continuous treatment processes will be planned using data obtained as a result of the batch study. The COD concentrations used in the present study ranged between 1850 mg/L to 2050 mg/L while the BOD concentrations range between 450 mg/L to 1250 mg/L. The effects of operating parameters on the chemical oxygen demand (COD) removal efficiency and the methane production rate were evaluated. COD removal efficiencies of 72.43% -92.70% were obtained for the cattle wastewater using a 3-14 d hydraulic retention time. The maximum COD removal was found in batch experiment 7, where the type of bacteria was actinobacteria, biochar dose was 20 g/L, pH was 7.5 and no inoculum dose was added this resulted in 92.70% COD removal efficiency. Hence, the batch study recommended using actinobacteria as a type of bacteria and Phragmites Australis biochar for continuous UASB reactors.

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