Theoretical Analysis of Biogas Production from Septic Tanks: The Case of the City of Kinshasa

As many think that respect for the environment, is not only a question intended for industrialists but has all the sectors of life, in particular sanitary also. In this regard, our article brings alternative management of human waste (excrement) to solve the problems that plague our dear beautiful capital, namely: 1) Lack of latrines that meet the standards;2) Emptying of septic tanks directly into the gutters and;3) Water pollution by sewage csompanies. In order to carry out the cartographic analysis of the study area, we used Shapefile data from the OpenStreetMap, Diva-Gis. These different data allowed us, analyzed, to categorize with the software ArArcGIS 0.8.1 to produce different zones according to the cases incurred in the city of Kinshasa. To do this, the analytical method uses the Buswell equation to determine the amount of gas contained in human excrement. Focusing on the analysis of the excrements produced by the population of age superior to 10 years, for 2023, we obtained: 138355.7283 m3/day of CH4 (885476.66 kWh/day or 885.476 MWh/day), which, energy can light: 138,355 lamps of 60 to 100 W for six hours or nearly 70,000 lamps of 60 to 100 W for 12 hours. Considering the last one which offers the lowest access rate, i.e. 3% of the district population to these latrines, we have: a) In Tshangu, we produce: 1618.762 3>/day (10360.07 kWh/day or 10.36 MWh/day) which can light nearly 1600 lamps from 60 to 100 W for six hours or nearly 800 lamps from 60 to 100 W for twelve hours. b) Mont-Amba, we produce 1402.927 3>/day (8978.73 kWh/day or 8.97 MWh/day) which can light nearly 1400 lamps from 60 to 100 W for six hours or nearly 700 lamps from 60 to 100 W for twelve hours;c) In Lukunga, we produce: 946.35 3>/day (6056.66 kWh/day or 6.056 MWh/day) which can light nearly 900 lamps from 60 to 100 W for six hours or nearly 450 lamps from 60 to 100 W for twelve hours. d) Funa, we produce: 182.629 3>/day (1168.83 kWh/day or 1.17 MWh/day) which can light almost 180 lamps from 60 to 100 W for six hours or almost 90 lamps from 60 to 100 W for twelve hours.

Treatment and utilization of septic tank effluent using vertical-flow constructed wetlands and vegetable hydroponics

Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD\-5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD\-5, SS, TN and TP were 71 4%, 97 5%, 96 9%, 86 3%, and 87 4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%—90% and 85%—96%, respectively.

Performance of hybrid constructed wetland systems for treating septic tank effluent

The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time （HRT） was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD （chemical oxygen demand） were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 （5 d biochemical oxygen demand） removal rate in four seasons. The average removal rates of TP （total phosphorous） could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN （total nitrogen） was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality fTom the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells （hybrid systems） showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.

Biodegradation Potential of Some Bacteria and Fungi Isolates from Septic Tank Sewage in Some Related Sites in Delta and Edo States of Nigeria

The biodegradation potentials of some selected bacteria isolated from septic tank sewage in the region under study were examined. Three replicate samples from Locations A, B and C representing Agbor, Benin and Sapele regions of Delta and Edo States, Nigeria respectively were collected from the influent tank (raw sewage) between November 2018 and January 2019 for testing. The sewage in 10 ml septic tubes for both experimental and control samples was subjected to shake flask biodegradation analysis using the isolates with the highest screen test result. A total of 18 bio-treatment options were available in this study. In the shake flask biodegradation of sewage using isolates, total organic carbon (TOC) values from day 0 to 25 in all isolates were lower compared with the control experiments. TOC values at day 25 were lowest (0.10 mg/L) in the treatment containing Bacillus sp. + Klebsiella sp. as compared to the TOC value (2.01 mg/L) of the treatment which had Aeromonas sp. + Bacillus sp. + Klebsiella sp. pH, EC, COD, TDS, DO and BOD were also monitored for a period of 3 weeks. In all treatment options, there was a rapid increase in the BOD for the experimental set up around day 10 - 20 which ranged between 74.82 - 187.54 mg/L. The overall physical observation (odour, consistency and colour) of the experimental and the control septic tubes showed very high remarkable reductions in the experimental set-up when compared with the observation made for the control samples.

An innovative design of septic tank for wastewater treatment and its performance evaluation： An applicable model for developing countries

A study was carried out to evaluate the treatment efficiency of modified model of septic tank（ST）for the treatment of domestic wastewater.The objective was to explore the possibility of increasing the removal efficiency,at household level,thereby reducing cost and treatment burden on city level treatment plants.For this purpose,a bench scale model of ST was prepared and operated continuously for 78 days at different detention times i.e.,48,24 and 12 h and at two reactor temperatures viz.15℃ and 25℃.Domestic wastewater was fed to the bench scale ST without pre-settling.Research was conducted under two different arrangements.Firstly,by installing baffles in the bench scale ST（called Run-1 setup）,and secondly by installing perforated plates between the baffles（called Run-2 setup）.Results demonstrated that Run-2 setup is better than Run-1 setup.Temperature significantly affects the efficiency.Detention time of 24 h was found feasible.Run-2 setup demonstrated a percentage BOD removal of 45%with effluent BOD of 113 mg·L^-1 at 15℃ and 85%removal with effluent BOD of 31 mg·L^-1 at 25℃.It is concluded that if a modified design of ST using Run-2 setup is provided at household level,the effluent coming out of the house will meet the National Environmental Quality Standards（NEQS）when reactor temperature is close to 25℃.Development authorities are suggested to change their by-laws and make modified ST mandatory for all households.This may significantly reduce the cost and footprint of city level wastewater treatment plants being planned.

五格式净粪池与三格式化粪池处理农村生活污水效果及成本对比

针对三格式化粪池(TcST)出水COD及氮、磷浓度高,直排或溢流造成当地局部水体污染或黑臭的问题,构建了等容积五格式净粪池(FcPTR),并以实际生活污水为处理对象,对比研究2种反应器的运行特性和单位污染物去除成本。结果表明:FcPTR连续运行120 d,出水COD平均值为74 mg/L,TN、NH_(4)^(+)-N、TP平均浓度分别为26、20、1.6 mg/L,在我国进水水质相似的农村地区使用时,可满足11个省(区、市)发布的农村生活污水处理设施水污染排放地方标准二级水质要求。厌氧折流区、好氧区填料与污泥上变形菌门(Proteobacteria)的生长代谢促进了含氮和含磷物质的去除。相比于TcST,FcPTR明显增强了系统对有机物的降解和脱氮除磷效果,提高了系统的抗冲击负荷能力。经成本核算,在设计容积和运行场景相同时运行10年,FcPTR削减1 kg COD、1 kgNH_(4)^(+)-N的成本均比TcST降低19.8%。

化粪池对城市排水系统水质水量及H_(2)S排放的影响

选择重庆市主城区住宅小区实地调研,对住宅小区化粪池进出口的污水水质、流量、H_(2)S等指标进行实测,分析取消化粪池对排水系统和周边环境的综合影响。结果表明:(1)从流量看,无论是工作日还是周末化粪池前后流量相差不大,取消化粪池对进入市政管网的污水总量影响不大;(2)从水质看,化粪池对COD、BOD_(5)、SS有较高削减率,且COD/TN的平均下降率为43%,COD/TP的平均下降率为38%;(3)从H_(2)S看,化粪池内H_(2)S平均浓度为8.20 mg/m^(3),污水管道内H_(2)S平均浓度为2.70 mg/m^(3),取消化粪池可有效降低可被人体感官明显察觉的臭气逸散的风险,对改善小区整体环境有积极效益。

基于实地调研的武汉市黄陂区红联村公共厕所设计研究

近些年随着乡村振兴的快速发展,农民生活质量的不断提高,对农村公共设施的需求正不断提升。但当前大多数农村缺乏公共厕所,少数有公共厕所的又不够完善。基于实地调研的方法,以武汉市黄陂区红联村的5座老旧公共厕所为调研对象,通过图表梳理出各种如厕痛点。采用装配式公共厕所,吊装式公共厕所2种方式进行红联村农村公共厕所的改造设计。同时运用三格化粪池的粪便处理方式,对红联村农村公共厕所进行无害化处理。期望能为武汉地区农村公共厕所的设计及建造提供有益借鉴。

组合式钢筋混凝土化粪池施工技术

目前,钢筋混凝土化粪池常采用两种施工方案,传统现浇施工方案和预制组合式钢筋混凝土成品化粪池施工方案,论文从工期、质量、安全、环保和工程造价5个方面对两种方案进行对比分析,详细介绍了组合式钢筋混凝土化粪池施工技术。

城镇高质量发展背景下化粪池取舍的探讨

目前,我国新型城镇化进程已迈入高质量发展阶段,城市更新、老旧小区改造、管网提质增效等项目正在稳步持续推进。在这些项目的实施过程中,关于化粪池的取消和改造一直是热点和难点问题。文章首先系统地分析了化粪池的设置初衷与现状问题,探讨化粪池取消的可行性和相应对策,最后提出,在市政污水管道质量较好的区域,管网末端已建成污水集中处理厂,可以不设化粪池;取消化粪池的地区,应重点针对小区内部的排水设施做好相应的保障措施;对于现存化粪池,应加强清掏管理和无害化处置。

五格式净粪池(FcPTR)启动特性研究

针对三格式化粪池(TcST)出水不达标的问题,构建了一种与TcST容积相等的五格式净粪池(FcPTR),开展FcPTR与TcST处理实际生活污水的启动特性对比研究。结果表明,第13天[水力停留时间(HRT)为80 h],FcPTR和TcST对CODCr的去除率分别降至44%和31%。第46天,通过降低HRT至36 h,FcPTR和TcST对CODCr的去除率分别升至86%和61%;FcPTR厌氧折流1区p H普遍大于厌氧折流2区,FcPTR厌氧区酸碱比为0.12~0.20,表明FcPTR具有较好的产酸产甲烷相分离特性。通过扫描电镜图分析FcPTR中填料挂膜和污泥生长情况,结果表明在第46天填料挂膜成功,污泥中微生物主要以短杆菌和球状菌为主。FcPTR相对于TcST具有较好的处理效果,CODCr出水达到GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准。

稻秆生物炭负载Fe/Ca对化粪池中磷的吸附特性

实现磷资源的高效回收和农业废弃物的资源化利用具有重要意义。采用氯化铁、硫酸铁、氯化钙对水稻秸秆生物炭(RSB)进行改性,得到3种改性稻秆生物炭(PRSB-Fe、PRSB-FS和PRSB-Ca),采用SEM、XPS、FTIR和BET对其进行表征,并通过批量实验探究其对模拟废水和化粪池粪污分离液中磷酸盐的吸附特性。模拟废水实验结果表明:伪二级动力学方程能更好地描述改性生物炭对磷的吸附过程(R2>0.99),吸附机制以化学吸附为主,吸附等温线均更符合Freundlich方程(20℃),表明多层吸附可能起主导作用。共存的Cl-基本不会影响3种改性生物炭对磷的吸附效果;对于初始磷浓度为(12.94±1.51)mg/g、pH值为7.4±0.2的化粪池粪污分离液,PRSB-Fe-5、PRSB-FS-5和PRSB-Ca-5对磷的吸附量分别是10.77、23.35、0.85 mg/g,其中PRSBFS-5对磷的吸附效果最好,去除率高达97.31%,剩余磷浓度仅有0.37 mg/L,达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。

社区化粪池污水能量转化估算与分析研究

以化粪池单元为研究对象,基于ADM1模型的反应过程,建立了社区化粪池污水能量转化核算模型(WeMax-STK模型),对污水能量在化粪池中的赋存、转化以及去向进行了分析,并评估了污水能量的回收潜力.结果表明,WeMax-STK模型整体可靠,模拟值与监测值的平均误差不超过24%,不确定性低于18%,模型准确率在70%以上.化粪池进水有机物转化为热能和内部微生物能量的比例约占进水总化学能量的17%,污水化学能的主要去向是转化为慢速降解基质的能量,化粪池内有机物转化为气态甲烷的能量仅占进水化学能总量的4%左右.污水热能的回收强度约4.6kWh/m3,热能回收潜力约为24%~25%,大约是污水化学能回收潜力的3~6倍.

人工湿地技术在农村生活污水中的应用

构建了基于人工湿地技术的农村生活污水处理系统,并将其应用在河南省新郑市某村。该处理系统主要采用“化粪池+折流厌氧反应器+跌水复氧+复合潜流人工湿地+稳定塘”组合工艺。实践表明,连续运行150 d内该工艺具有较好的处理效果,对COD、NH3-N、TN、TP的平均去除率分别为72.1%、66.8%、64.2%和54.8%,系统出水水质达到河南省《农村生活污水处理设施水污染物排放标准》(DB 41/1820—2019)一级标准。该工程可为河南省农村生活污水处理的技术选择和运行提供参考。

关于城市排水系统中取消化粪池的探讨

我国城市排水系统日趋完善,化粪池的设置、安全、管理、维护等问题尤为突出,取消应是大势所趋。由于目前我国对化粪池设置规定不明确,导致在城市更新、老旧小区改造、海绵城市建设等项目中,仍在新建或改造化粪池。本文通过对化粪池的功能和存在的问题展开分析,并从政策、技术、实践三个角度探讨了取消化粪池的可行性;结论表明,在我国现状的城市排水系统中,取消化粪池是可行的,也是必要的。

农村地区生活污水处理研究

该文对于农村地区居住分散、生活污水难以集中处理的情况进行分析,采用化粪池与人工湿地联用的方式对生活污水进行处理,并对氨氮、SS(悬浮物)、水力停留时间(HRT)与化学需氧量(CODcr)的去除效果进行分析,研究结果对于农村地区污水处理有参考价值。

取消化粪池的可行性分析与合理性建议

近年来,随着我国城市排水系统愈加完善,化粪池存在的必要性正在逐步削弱,GB 50014—2021《室外排水设计标准》首次明确规定了化粪池设置的条件。从化粪池的起源入手,分析了化粪池存在的弊端,然后从政策、技术、经济、管理等层面分析了污水集中处理设施代替化粪池的可行性,最后从设计到施工、从运维到管理,分别针对可能出现的问题提出了合理性建议,为日后城市排水系统的设计、施工及运维提供了新的思路。

城市粪便污水处理新模式探讨

随着经济水平的提升,城市污水系统逐步完善,结合城市现有污水处理设施建设粪便污水处理设施逐渐成为各大城市关注热点。本文针对粪便污水的集中式处理与分散式处理进行比较,论述了粪便污水分散式处理占地少、投资小、建设快和碳源回收利用等优势。同时,通过对南宁市中心城区粪便污水处理项目实践探究,论述城市粪便污水处理的分散式处理模式,较集中式处理模式而言,即保证了处理效果,同时缩短了项目建设周期及建设成本。

化粪池可燃气体分析及安全运行研究

简要介绍了化粪池内可燃气体的来源及特性,并对北京市朝阳区78座公厕进行了甲烷浓度检测,数据分析发现,所测化粪池均有不同浓度的甲烷气体存在,甲烷浓度受季节、粪便量和清掏时间以及人们的生活活动带来的排污特征等因素影响,部分化粪池存在明显的安全隐患。针对数据分析结果,提出了优化化粪池通风设计、定期清掏化粪池并增加频次、应用在线监测手段强化化粪池安全运行监管的建议。

绿色电网项目一体化雨污处理施工技术

以某变电站为例,对绿色电网项目一体化雨污处理施工技术进行研究,综述了使用一体化污水处理设备,配置洗车槽和冲厕废水循环系统,配置污水统一收集系统,配置绿化、扬尘、场地冲洗和混凝土养护废水使用系统,解决了工程施工过程中雨污循环使用问题,不仅节约了水资源,降低了成本,绿色节能环保,而且提升了3C绿色电网建设。