Assessment of the use of precipitating agents and ceramic membranes for treatment of effluents with high concentrations of nitrogen and phosphorus from recirculating aquaculture systems

Abstract

Following the culturing of post‐juvenile African catfish, wastewaters were purified using single and integrated processes. Iron coagulant (IC), aluminium coagulant (AC), lanthanum modified bentonite (LMB) and ceramic membranes (NF – nanofiltration) were each tested in single processes, while the combination of IC + NF and AC + NF were used in the integrated process tests. Among the single processes, membrane filtration was the most effective in purifying the aquaculture effluent. The total suspended solids (TSS) were removed entirely and there was a near‐complete removal of turbidity (99.2%), as well as effective removal of Al and Fe (80.8% and 67.4% respectively). Precipitating agents overall removed TSS most faithfully, from 37.5% removal with AC, through 50.2% with IC, to 62.3% with LMB. Using integrated processes, the highest removal efficacy was recorded for TSS (100%) and turbidity (99.7% – IC + NF; 99.9% – AC + NF). Additionally, integrated processes attained a 96.8%–98.4% removal of NO2‐‐N. This study confirms the possibility of using IC, AC and LMB in chemical purification of effluents from recirculating aquaculture systems (RAS). However, due to their low removal efficacy for nitrogen and phosphorus, it is preferable to use NF or integrated processes – membrane filtration combined with chemical precipitation, methods which proved to be most effective for water purification in RAS.

Effect of pH on Total Volume Membrane Charge Density in the Nanofiltration of Aqueous Solutions of Nitrate Salts of Heavy Metals

“…More details regarding the experimental set-up can be found in [ 60 ]. After each filtration, the membrane was chemically cleaned according to the manufacturer’s recommendations, described by Nędzarek et al [ 30 ] and Bonisławska et al [ 61 ]: washing with 2% NaOH solution (T = 360 K, t = 40 min), rinsing with ultra-pure water, washing with 0.5% HNO 3 solution (T = 320 K, t = 30 min), and, finally, rinsing three times with ultra-pure water. Chemical washing resulted in a performance characteristic for a clean membrane.…”

The Fouling Effect on Commercial Ceramic Membranes during Filtration of Microalgae Chlorella vulgaris and Monoraphidium contortum

“…At the same time, microalgae can be grown without competing for arable land, and in harsh conditions (e.g., salt water) and recirculating systems as an additional component of the water purification system. Such purification systems (photobioreactors producing microalgae biomass) can be successfully used, for example, during intensive fish farming in recirculating aquaculture systems (RAS) where the water is abundant in nutrients necessary for microalgae [4][5][6].…”

“…Promising alternatives are processes based on the use of membranes, such as in microfiltration (MF) and ultrafiltration (UF), widely used in the separation, recovery and fractionation of biomolecules from various types of streams, such as wastewaters, byproducts and natural sources [3,6,12,13].…”

Potential of valuable materials recovery from aquaculture wastewater: An introduction to resource reclamation

“…Similarly, Ebeling et al (2003) explored the performance of alum coagulation and flocculation to remove total suspended solid parameters from aquaculture wastewater and showed that it had a removal efficiency of up to 92%. Bonisławska et al (2019) highlighted the efficiency of suspended solid removal of up to 100% using the filtration method. Chen et al (2015) indicated the performance of organic matter removal from aquaculture wastewater using ozonation‐membrane filtration with a removal efficiency of 52.1%.…”