Chemical Engeneering

Proses dimana CO2 dalam feed gas dihilangkan mengguakan aMDEA di dalam sebuah vessel counter current, terjadi reaksi eksotermis dan CO2 yang bereaksi dengan air menjadi H2CO3 yang ion CO3 nya akan diserap oleh aMDEA. Vessel tersebut memiliki 31 valve tray (dipilih karena cocok untuk laju fluida yang fluktuatif), 2 bubble tray untuk mengalirkan BFW, dan demister pad untuk memisahkan condensate pada feed gas saat masuk vessel. Sweet gas keluaran vessel akan didinginkan oleh air laut menjadi 36 o C sebelum masuk absorber overhead yang akan didingankan lebih lanjut hingga 19 o C mengunakan propan sehingga aMDEA yang terbawa dapat di kondensasikan dan dialirkan ke amine flash drum.

Most of the wastewater treatment systems in small rural communities of the Cova da Beira region (Portugal) consist of constructed wetlands (CW) with horizontal subsurface flow (HSSF). It is believed that those systems allow the compliance of discharge standards as well as the production of final effluents with suitability for reuse. Results obtained in a nine-month campaign in an HSSF bed pointed out that COD and TSS removal were lower than expected. A discrete sampling also showed that removal of TC, FC and HE was not enough to fulfill international irrigation goals. However, the bed had a very good response to variation of incoming nitrogen loads presenting high removal of nitrogen forms. A good correlation between mass load and mass removal rate was observed for BOD5, COD, TN, NH4-N, TP and TSS, which shows a satisfactory response of the bed to the variable incoming loads. The entrance of excessive loads of organic matter and solids contributed for the decrease of the effective volume for pollutant uptake and therefore, may have negatively influenced the treatment capability. Primary treatment should be improved in order to decrease the variation of incoming organic and solid loads and to improve the removal of COD, solids and pathogenic. The final effluent presented good physical–chemical quality to be reused for irrigation, which is the most likely application in the area.

We present a numerical solution for the dead zone model which describes the solute transport in a subsurface and horizontal flow constructed wetland. This model is a system of two mass balance equations for two conceptual areas: the main channel and the storage zone. We use finite difference schemes to determine the numerical solution of the system and we study its convergence by presenting properties related to the stability and accuracy of the schemes.

Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration membranes and five fractions were obtained: four retentates (>100, 50-100, 20-50 and 10-20 kDa) and one permeate (<10 kDa); which were used to study the correlation of molecular size with biodegradability and toxicity before and after ozonation. The results show that molecular size is correlated with organic load and restrains biodegradability. The fraction with >100 kDa corresponds to 56% of the organic load and the one with <10 kDa only 8%. The biodegradability of fractions increased 182% with fractions molecular size reduction from >100 to < 10 kDa and the chemical oxygen demand (COD) was from 3436 to 386 mg L À1 . For biodegradability enhancement the best outcome of ozonation was obtained with compounds having molecular size >20 kDa and range from 5% up to 175% for applied ozone doses to COD ratios between 0.15 and 0.38.

Self-assembly is a widely studied, spontaneous, and reversible phenomenon leading to formation of the ordered structures by non-covalent specific interactions among starting molecules. In this work, a new template for the self-assembly of polypeptides based on peptides containing the C-terminal histidinehydroxamic acid moiety and Cu2+ ions is characterized. Two peptide (tripeptide and pentadecapeptide) hydroxamic acid systems were synthesized and their interactions with Cu2+ ions were investigated revealing a high stability of the supramolecular assemblies formed. The supramolecular metallacrown-based L4Cu5 complexes exist at physiological pH in the presence of Cu2+ ions as is evidenced from the spectroscopic methods, ESI mass spectrometry, and physicochemical techniques.

We present a numerical solution for the dead zone model which describes the solute transport in a subsurface and horizontal flow constructed wetland. This model is a system of two mass balance equations for two conceptual areas: the main channel and the storage zone. We use finite difference schemes to determine the numerical solution of the system and we study its convergence by presenting properties related to the stability and accuracy of the schemes. Concerning the experimental results, the magnitude of the longitudinal dispersion and the extension of dead volumes is estimated for clean conditions and after a certain operating period under organic loading conditions. The results showed a considerable amount of longitudinal dispersion through the bed, which was very strong near the feeding point, indicating the occurrence of mixing and significant presence of dead zones and short-circuiting.