Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Avenida Trabalhador São-Carlense, 400, São Carlos, São Paulo, 13566-590, Brazil.
Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Avenida Trabalhador São-Carlense, 400, São Carlos, São Paulo, 13566-590, Brazil.
J Environ Manage. 2021 Jun 15;288:112412. doi: 10.1016/j.jenvman.2021.112412. Epub 2021 Apr 7.
This study evaluated the impact of a 50% reduction of filter media depth in Household Slow Sand Filters (HSSFs) on continuous flow to remove physicochemical and microbiological parameters from river water. Furthermore, simple pre-treatment and disinfection processes were evaluated as additional treatments. Two filter models with different filtration layer depths were evaluated: a traditional one with 50 cm media depth (T-HSSF) and a compact one (C-HSSF) with 25 cm. HSSFs were fed with pre-treated river water (24-h water sedimentation followed by synthetic fabric filtration) for 436 days at a constant filtration rate of 0.90 m m day with a daily production of 48 L day. Sodium hypochlorite (2.0 mg L of NaOCl 2.5% for 30 min) was used to disinfect the filtered water. Water samples were analysed weekly for parameters such as turbidity, organic matter, colour and E. coli, among others. Removal of protozoan cysts and oocysts by the HSSFs were also evaluated. After pretreatment, turbidity from the HSSF river water was reduced to 13.2 ± 14.6 NTU, allowing the filters to operate. Statistical analysis indicated no significant difference (p > 0.05) between T-HSSF and C-HSSF efficiencies in all evaluated parameters throughout operation time. Hence, media depth reduction did not hinder continuous HSSF performance for almost all the evaluated parameters. However, it may have affected Giardia cysts retaining, which passed through the thinner media on one evaluation day. Disinfection was effective in reducing remaining bacteria from filtered water; however, it was ineffective to inactivate protozoa. The reduction in the filtration layer did not affect the overall filtered water quality or quantity showing that a compact HSSF model may be a viable option for decentralized water treatment.
本研究评估了家用慢滤池（HSSF）中过滤介质深度减少 50%对连续流动的影响，以去除河水的物理化学和微生物参数。此外，还评估了简单的预处理和消毒工艺作为附加处理。评估了两种具有不同过滤层深度的过滤模型：传统模型，过滤介质深度为 50cm（T-HSSF）和紧凑型模型（C-HSSF），过滤介质深度为 25cm。HSSF 以 0.90m m day 的恒定过滤速率连续运行 436 天，每天产水量为 48L。过滤后的河水先经过 24 小时沉淀和合成纤维过滤，再用次氯酸钠（2.0mg L 的有效氯 2.5%，消毒 30 分钟）消毒。每周分析水样，评估浊度、有机物、颜色和大肠杆菌等参数。还评估了 HSSF 对原生动物孢囊和卵囊的去除效果。预处理后，HSSF 河水的浊度降低至 13.2±14.6NTU，允许过滤器运行。统计分析表明，在整个运行时间内，T-HSSF 和 C-HSSF 在所有评估参数上的效率没有显著差异（p＞0.05）。因此，介质深度的降低并没有阻碍几乎所有评估参数的连续 HSSF 性能。然而，它可能影响到贾第虫孢囊的截留，因为在一天的评估中，这些孢囊通过较薄的介质穿过。消毒有效地降低了过滤水中残留的细菌；然而，它对原虫无效。过滤层的减少并没有影响到整体过滤水的质量或数量，这表明紧凑型 HSSF 模型可能是分散式水处理的一种可行选择。
