Simulation and optimization of a lamella settler for cattle feedlot wastewater treatment and nutrients recovery. Experimental validation in the field

Abstract

Cattle concentrated animal feeding operations (feedlots), whose number has grown considerably in the last years, generate large volumes of wastewaters with a high organic load. The wastewaters are formed by rainfall-runoff of the accumulated manure and may contain hormones and antibiotics, which hampers the use of biological treatments. In this work, the feasibility of continuous separation of the suspended colloidal organic matter and nutrients to clarify the liquid and recover the solid is studied. A flocculation sedimentation system using a decentralized lamella settler is proposed, optimized and further tested in the field. Computational fluid dynamic (CFD) simulation is used to analyze the motion of the liquid and suspended inertial particles representing the formed flocs, for optimizing the settler. The simulations helped in the design of the bench-scale unit tested in the field. The clarified liquid was characterized to analyze its use for fertigation. The proposed treatment allowed excellent removal of organic matter (~98% chemical oxygen demand, and almost complete turbidity) and phosphorus (~95%). Organic nitrogen was partially removed (~70%) and ammonia nitrogen mostly remained in the liquid. Spectral characterization of the clarified liquid suggests that the remaining organic nitrogen is related to soluble protein-like compounds.

Potential use of treated wastewater from a cattle operation in the fertigation of organic carrots

“…Thus, in these experimental conditions, the different treatments provided adequate mineral nutrition, in relation to the analyzed element (N), as the soil must have adequate chemical and physical properties (Farhangi-Abriz and Ghassemi-Golezani, 2019) and the higher N rate of the dairy cattle slurry (DCS) proved useful for the circular nutrient economy, while improving the physical and chemical quality of the soil and the sustainability of the agricultural system as a whole (Bosch-Serra et al, 2020); however, depending on the type of treatment used, organic nitrogen can only be partially removed (~70%), and the ammonia nitrogen remained mainly in the liquid (Fleite et al, 2020). Still, temperate pasture species constitute a source of protein for dairy cattle (Almeida et al, 2020), and the presence of these compounds may explain how some substances may be more present in DCW than in others, due to the lower capacity to remove some processes, all of which influence the composition of the DCW.…”

“…Despite the benefits of wastewater, the nutrients present in excess in reused waters can induce excessive vegetative growth and, with respect to the environment, contaminate surface water and groundwater, if wastewater management is not carried out in a controlled manner (Díaz et al, 2013). Therefore, it becomes crucial to adopt control and investigation instruments and regulations to determine the presence of pollutants and control the quantity of wastewater disposed in the soil (Tripathi et al, 2019;Fleite et al, 2020). Reused water can sometimes possess a high pathogenic load, which can cause diseases in humans and animals that come into contact with it (Moussaoui et al, 2019;Tripathi et al, 2019).…”

“…In the literature, a high degree of disagreement prevails in terms of the health risks caused by the use of wastewater from animal husbandry in agriculture (Fleite et al, 2020;Janeiro et al, 2020;Kumar et al, 2021). Hussar et al (2003) recorded higher productivity after utilizing treated swine wastewater in carrot fertigation than with the use of a traditional cultivation system (chemical fertilization plus irrigation).…”

“…Cattle excreta has been in use as an organic fertilizer for a long time, especially for agricultural crops such as vegetables, many of which are consumed raw (Almeida et al, 2020;Bosch-Serra et al, 2020;Fleite et al, 2020). Thus, natural fertilizers for sustainable productivity and the desired quality of carrot roots are increasingly requested and investigated (Ahmad et al, 2016).…”

Flux Improvement and Biofilm Performance of an Oblique Gravity-Driven Ceramic Membrane Bioreactor Coupled with Electrocoagulation for Roofing Rainwater Purification

“…Thus, the sedimentation efficiency of EC flocs might determine the biofilm formation and its porosity. Also, it was acknowledged that the inclined plates in the lamella gravity settlers could improve the sedimentation efficiency with the increasing effective surface area compared to the conventional tanks. , The larger-sized floc would be settling on the ceramic membrane more quickly and aggregating and compacting in the continuous-flow bioreactor improving the biofilm formation, which was responsible for the residual contaminants’ removal, including organic matters, nitrogen, and phosphorus. Moreover, the generated filter cake also could inhibit some impurities flowing into the membrane channel and resulting in the membrane blocking. , Thus, inspired by the shallow pool theory, an oblique gravity-driven ceramic membrane bioreactor was involved in the EC/GDCMBR process (oblique-EC/GDCMBR) to accelerate the floc precipitation efficiency on the ceramic membrane.…”