The removal of arsenic was investigated by four types of thin-film polyamide nanofiltration (NF) (NF270, NF90) and reverse osmosis (RO) (XLE, BW30) membranes in a flat-sheet module. The influence of membrane types, pressure, pH, and pre-oxidation step on the removal of arsenic (As(III)) was investigated. Initial As(III) concentration was 100 μg/l for all of the experiments. Flux was determined over a pressure range of 3.5–10 bar for both NF and RO membranes. Experiments were conducted at pH 3.5, 5, 7.5, and 10 to evaluate the effect of pH on As(III) removal. The impact of pre-oxidation and oxidant concentrations on As(III) removal were also evaluated. It was found that the percentage of As(III) removal of RO membranes were in the range of 97–99 for all transmembrane pressure applied. In the range of operating conditions, As(III) and As(V) rejection were found almost equally good by RO membranes. RO permeate met the WHO and Turkish standard for arsenic. Pre-oxidation step improved the rejection performance of NF. Nevertheless, NF permeate did not meet the standards in the range of operating conditions.

Bioflocculants can be used for cost-effective harvesting of microalgae biomass on an industrial scale. This study investigates the flocculation-based harvesting approach to recovering Chlorella vulgaris microalgae biomass using chitosan biopolymer. Response surface methodology (RSM) was used to design the experiments and optimize the critical operating parameters. Box-Behnken Design (BBD) was employed at three levels, and 17 experimental runs were conducted to determine the optimal conditions and the relationship between operating parameters. The highest biomass recovery of 99.10% was achieved at the following optimized conditions: pH of 5, flocculation time of 45 min, and chitosan concentration of 10 mg/L. Both experimental results and model outputs indicated that pH significantly impacts microalgae harvesting and that process performance is less dependent on chitosan concentration and flocculation time. The quadratic model has shown the best fit with the experimental results. The results could be applied to large-scale microalgae harvesting applications to promote microalgae biomass recovery and reduce operating costs.

Enerji ihtiyacının büyük bir bölümünü karşılayan fosil yakıt rezervleri hızla tükenmektedir ve bu yakıtların çevresel zararları her geçen gün artmaktadır. Bu sebeple, tüm gelişmiş ve gelişmekte olan ülkeler gibi ülkemiz de yenilenebilir enerji kaynaklarının kullanımına yönelmiştir. Bu kapsamda ülkemizde, yenilenebilir enerji yasası çıkarılarak yenilenebilir enerji kaynaklarının ekonomiye kazandırılması, sürdürülebilir enerji üretiminin desteklenmesi ve çevrenin korunması amaçlanmıştır. Son dönemde önemi artan yenilenebilir enerji kaynaklarından bir tanesi de biyokütle enerjisidir. Biyokütle enerji kaynağı olarak, ana bileşenleri karbonhidrat bileşikleri olan bitkisel ve hayvansal kökenli tüm organik maddeler kullanılabilmektedir. Bu enerji kaynakları içerisinde mikroalgler, yüksek fotosentetik etkinlikleri, yüksek biyokütle üretimleri ve hızlı çoğalmaları gibi avantajlarıyla biyoyakıt üretimi için umut verici görülmektedir. Mikroalglerden, biyokimyasal yöntemler ile elektrik, etanol, hidrojen, metan ve biyoyağ üretilebildiği gibi termokimyasal yöntemler kullanılarak singaz, biyoyağ ve elektrik üretilebilmektedir. Bu derleme makalesinde, mikroalglerin izolasyonu, mikroalgal biyokütle üretimi, biyokütlenin hasadında kullanılan yöntemler ve mikroalglerin yenilenebilir biyoyakıtlar için ham madde kaynağı olarak kullanılabilirliği ele alınmıştır.

The main product of the conversion process of organic wastes to a useful organic fertilizer, known as compost, has gained an increasing interest in management of organic wastes recently. One of the main problems arising in the composting facilities is the high organic loaded leachate. In this study, a treatability experiment for composting leachate from a full-scale composting facility was carried out with the combination of membrane processes. The parameters such as chemical oxygen demand, total organic carbon, Cl⁻ and were analysed to evaluate the membrane treatment performances of single and combined membrane systems consisting centrifuge, cartridge filter, ultrafiltration and nanofiltration membranes. The removal efficiencies of all pollutants were observed between 4.4 and 98%. The highest removal efficiencies were observed with the nanofiltration membrane (NF90) having a lower molecular weight cut-off than the others used in this study. It was observed that the effluent of NF90 membrane did not exceed the allowed maximum COD value.