Adsorption and desorption of nutrients from abattoir wastewater: modelling and comparison of rice, coconut and coffee husk biochar

Abstract

Enrichment of water bodies with nutrients from wastewater is one of the causes of eutrophication to aquatic ecosystems. This study investigated the use of biochar derived from rice husk, coconut husk, and coffee husk in adsorbing nitrates (NO3-N) and nitrites (NO2-N) from slaughterhouse wastewater. It also explored the desorption efficiencies of the adsorbed nutrients to ascertain the applicability of the enriched biochars as slow-release fertilizers. To characterize the physicochemical properties of the biochars, scanning electron microscopy (SEM) was used. Fourier transforms infrared spectroscopy (FTIR), elemental analysis (CHNO) Langmuir and Freundlich, and the isotherm models were employed to fit the experimental equilibrium adsorption data. It was observed that the Langmuir isotherm model has the best fit of NO3-N and NO2-N on all the biochars. And this was based on the coefficient of correlation values. Also, the coconut husk biochar has the highest adsorption capacities of NO3-N and NO2-N at 12.97 mg/g, and 0.244 mg/g, respectively, attributing to its high porosity as revealed by the SEM images. The adsorption capacities for the rice husk char were 12.315 and 0.233 mg/g, while that for coffee husk char were12.08 mg/g and 0.218 mg/g for NO3-N and NO2-N, respectively. The relatively higher amount of NO3-N adsorbed to that of NO2-N could be attributed to its higher initial concentration in the solution than nitrite concentration. The desorption efficiencies of nitrates were 22.4, 24.39, and 16.79 %, for rice husk char, coconut husk char and coffee husk char, respectively. For the rice husk char, coconut husk char and coffee husk char, the nitrites desorption efficiencies were 80.73, 91.39, and 83.62 %, respectively. These values are good indicators that the studied biochar can be enriched with NO3-N and NO2-N and used as slow-release fertilizers.

Studies on the efficiency of fish scale adsorbents for treatment of fish processing effluent

“…The improved porous nature of fish scale biochar might be due to the high processing temperature when compared with dried fish scale adsorbent. Further investigation of the elemental analysis results was given in Table 5 which reveals that carbon was present in higher levels than other elements, possibly indicating the dominance of carbon‐containing functional groups 43 in adsorbents used in this study. The content (%) of other elements such as sodium, magnesium, and calcium showed a slight increase in biochar compared to dried fish scale adsorbent, whereas the composition of N and P showed unpredictable trends 10 .…”

Coffee Husk and Lignin Revalorization: Modification with Ag Nanoparticles for Heavy Metals Removal and Antifungal Assays

“…The black patches on Figure 1a,b are probably pore apertures and cavities, which may influence the increase in sorption kinetics [42][43][44]. On the other hand, Figure 1c shows some changes in the coffee husk morphology.…”

“…The FT-IR spectra is presented in Figure 2. The peak around 3328 cm −1 is attributed to the −OH stretching as a result of functional groups of cellulose, hemicellulose, and lignin [44,49]. The peak of 2919 cm −1 corresponds to C-H groups, 1731 cm −1 , 1639 cm −1 C=O of aldehyde and ketone groups, 1458 cm −1 from aromatic C=C stretching groups and CH 2 and CH 3 groups, around 1371 cm −1 from aromatic C-H stretching and carboxyl−carbonate structures, 1238 cm −1 from CHOH groups, and around 1029 cm −1 Si-O-Si group [42,44,49,50].…”

Adsorção de poluentes em águas residuárias utilizando biocarvão: revisão sistemática

“…De forma geral, como os estudos de caso são recentes, a maioria dos experimentos se encontra ainda em fase inicial, realizados em bancada e com efluente artificial. Dos 63 artigos analisados, apenas 18 utilizaram água residual real para os experimentos, com origens diversificadas como por exemplo: efluentes de pirólise (Caprariis et al, 2017), efluentes de coque (Shi et al, 2020), efluente da produção de gás de xisto (Shang et al, 2020), efluente de abatedouro (Konneh et al, 2021), lodo fecal bruto e efluente de esgoto (Mamera et al, 2022), efluente de ETE (Dalahmeh et al, 2018), efluente agrícola (Hu et al, 2022), efluente industrial de galvanoplastia de liga de Zn-Ni (Wang et al, 2020) e efluente de curtume (Hashem et al, 2020).…”