Houbron E, González-López G I, Cano-Lozano V, Rustrían E
Facultad de Ciencias Químicas, Universidad Veracruzana, Orizaba Ver, México.
Water Sci Technol. 2008;58(7):1415-21. doi: 10.2166/wst.2008.492.
This study attempted to investigate the impact of HRT of treated leachate recirculation on hydrolysis solubilization rate of coffee pulp in an acidogenic reactor. Coffee pulp presents more than 70% of organic matter and around of 30% of lignin and cellulose. Five lab scale reactors of 20 litres were used. Each reactor was fed with 5 kg of fresh coffee pulp and anaerobic sludge was used as inoculate. HRT of 0.5, 1, 3 and 10 days were applied. Each experiment shows that Total, Soluble and VFA COD appear rapidly in the removed leachate. HRT have a great impact on hydrolytic rate with an optimal value of 32,000 mg x L(-1) x d(-1).Low HRT increases hydrolysis rate and in consequence reduces duration of the hydrolytic phase. Also composition and concentration of VFA are influenced by HRT. Low ones favour acetic acid production and high ones permit the production of butyric. Low HRT generates leachate more easily fermentable. Efficiency of solubilization and acidification are independent of the HRT and present average values of 78% and 65% respectively. By batch feeding solid and continuous recirculation of treated leachate, HRT and SRT could be dissociated, where solid had a very high retention without problems of load, mixing and inhibition, and liquid could be recirculated with a very high rate. Under these low HRT condition, the first reactor of a two stage anaerobic system could reduces the hydrolysis duration of organic solid waste like coffee pulp and generate an optimal leachate for the methanization process.
本研究试图调查处理后的渗滤液回流的水力停留时间（HRT）对产酸反应器中咖啡果肉水解溶解速率的影响。咖啡果肉含有超过70%的有机物以及约30%的木质素和纤维素。使用了五个20升的实验室规模反应器。每个反应器加入5千克新鲜咖啡果肉，并使用厌氧污泥作为接种物。采用了0.5天、1天、3天和10天的HRT。每个实验表明，在去除的渗滤液中总化学需氧量（COD）、可溶性COD和挥发性脂肪酸（VFA）的COD迅速出现。HRT对水解速率有很大影响，最佳值为32,000毫克·升⁻¹·天⁻¹。低HRT会提高水解速率，从而缩短水解阶段的持续时间。此外，VFA的组成和浓度也受HRT影响。低HRT有利于乙酸的产生，高HRT则有利于丁酸的产生。低HRT产生的渗滤液更易于发酵。溶解和酸化效率与HRT无关，分别呈现78%和65%的平均值。通过分批进料固体和连续回流处理后的渗滤液，可以使HRT和固体停留时间（SRT）分离，其中固体具有非常高的保留率，不存在负荷、混合和抑制问题，液体可以以非常高的速率回流。在这些低HRT条件下，两级厌氧系统的第一个反应器可以缩短像咖啡果肉这样的有机固体废物的水解持续时间，并为甲烷化过程产生最佳渗滤液。
