ISSN: 1659-2751


Implementation and Monitoring of the Initial Stage of the Residual Water Treatment Plant at the Food Processing Laboratory at EARTH University


The objective of the present study was to implement a decontamination system for the residual water generated by the food-processing laboratory at EARTH University. This system consists of a preliminary treatment (tank with grease trap); a flow equalization tank; the main component of the system, a secondary biological treatment of activated sludge (in an aeration tank and a sedimentation tank); and two advanced wastewater treatments consisting of first, a subsurface slow sand filter with ascending flow, and second, a surface wetland. Throughout the nine weeks of sampling during the present study, the results of the analysis of the indicators confirmed that the system effectively reduced the contamination in the residual water from the food-processing laboratory by reducing the concentrations of BOD5 and neutralizing the pH. The results of the analysis were within the parameters set by the national laws ofCosta Rica. Although the concentrations of nitrate and suspended solids also were reduced throughout the system, the levels often were in excess of those allowable by law. The concentration of phosphate throughout the system always was in excess of those levels permissible in this country. After the EM applications, microscopic analysis confirmed the presence of the microorganisms that are indicators of an effective biological treatment of activated sludge.

Key words: Residual water, BOD5, phosphates, superficial wetland, sub-superficial wetland, activated sludge, nitrates, potassium.

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