Optimization of nitrogen and phosphorus removal from pig slaughterhouse and packing plant wastewater through electrocoagulation in a batch reactor

Fábio Orssatto,Maria Hermínia Ferreira Tavares,Flávia Manente Da Silva,Eduardo Eyng,Leandro Fleck

doi:10.4136/ambi-agua.2233

Abstract

This work evaluated the removal of total Kjeldahl nitrogen (TKN) and total phosphorus (P) through electrocoagulation and used aluminum electrodes to optimize the potential differential (pd) and hydraulic retention time (HRT) variables in a batch reactor. The experimental design used was Rotatable Central Composite Design (RCCD). The application of the electrocoagulation in the treatment of effluents from pig slaughterhouses and packing plants proved to be efficient in relation to the removal of TKN and total phosphorus, obtaining maximum efficiency equal to 67.15% and 99%, respectively. The maximum TKN removal value was found in Test 12, where treatment conditions were 30 minutes for HRT and 20 volts for pd, which corresponds to 0.86 A of electric current and a current density of 17.2 mA cm-2. For P, the only test that removed below 99% was the first. Through statistical analyses, it was only possible to obtain a mathematical model for TKN removal. While the response surface graph did not present a defined range of the best conditions for the independent variables, it was possible to observe the tendency for better removal, a wide range of pd and values over 30 minutes for retention time.

Highlights

The production of pork in Brazil has great relevance for the country's economy
The analysis of variance (ANOVA) of the results found for the removal of total Kjeldahl nitrogen (TKN) showed that the obtained model fits the data, since the p-value was 0.004685, with a variation percentage of explained variation (R2) of 91.12% evidencing a valid model
The objective of this work was to evaluate the removal of total Kjeldahl nitrogen (TKN) and total phosphorus (P) through the electrochemical technique, and to optimize the potential differential and hydraulic retention time (HRT) variables in a batch reactor of electrocoagulation using aluminum electrodes

Summary

Introduction

The production of pork in Brazil has great relevance for the country's economy. According to ABPA (2017), Brazil produced 3.73 million tons of pork in 2016, ranking 4th in the world.Pig slaughterhouses and packing plants generate a large amount of effluents, which consist of protein, fat, salts, animal manure and other substances. The production of pork in Brazil has great relevance for the country's economy. According to ABPA (2017), Brazil produced 3.73 million tons of pork in 2016, ranking 4th in the world. Pig slaughterhouses and packing plants generate a large amount of effluents, which consist of protein, fat, salts, animal manure and other substances. This waste has a high degree of pollution, with high levels of organic matter, oils and greases, nutrients and total solids. In addition to the high degree of pollution, the meat processing industry produces large volumes of wastewater due to the slaughter of animals and the cleaning of slaughterhouses and meat processing plants (Bustillo-Lecompte and Mehrvar, 2015). The meat processing industry uses 24% of the total fresh water consumed by the food and beverage industry and up to 29% of the worldwide agricultural sector demand (Mekonnen and Hoekstra, 2012; Gerbens-Leenes et al, 2013)

Objectives

Methods

Results

Conclusion