排水研究新热点--从污水处理过程中回收磷

磷是一种不可更新、难以替代的有限自然资源.因控制水体富营养化而实施的生物营养物去除为从污水中回收磷创造了条件,以鸟粪石等磷酸盐沉淀方式从处理过程中回收磷并用于肥料或磷酸盐制造业原料已成为排水界研究的新热点.基于第二届磷回收国际学术会议论点与结论,阐述了磷回收的基本概念、应用实例、污泥管理、应用技术、经济分析等方面的情况.     

欧洲城市污水处理技术新概念——可持续生物除磷脱氮工艺(上)

传统污水处理工艺以能消能 ,消耗大量有机碳源 ,剩余污泥产量大 ,同时释放较多CO2(因耗能 )到大气之中。当今 ,全球普遍强调的可持续发展经济模式在污水处理领域也得到体现。因此 ,研发以节省能 (资 )源消耗、并最大程度回收 (用 )有用能 (资 )源的可持续污水处理工艺已势在必行 ,在详细介绍两种新近在欧洲出现的可持续处理工艺———反硝化除磷、厌氧氨 (氮 )氧化的基础上 ,提出一个以转换有机能源 (甲烷 )、回收磷酸盐 (鸟粪石 )、回用处理水 (非饮用目的 )为目标的可持续城市污水生物除磷脱氮推荐工艺     

基于源分离的农村分散式生活污水处理技术

与城市集中式生活污水处理相比,农村分散式生活污水处理可以采用源分离技术与污水资源回收处理技术相结合的模式,从而有效回收污水中的营养盐、减少排放到环境中的污染物、提高水的循环利用效率。本文提出了三种源分离生活污水,包括尿液,灰水(洗浴、洗衣水等)和粪便。尿液不到家庭废水总量的1%,却含有50%～80%的氮、磷和钾等营养盐以及大部分药物和激素。粪便含有较高的有机物、固体和病原菌,并携带剩余的药物/激素残留物。灰水量最大,但是在三类污水中其营养盐、病原菌的含量最低,但含有洗涤剂和个人护理产品等污染物。提出了两种模式的生活污水源分离及污水处理技术。尿液的最佳处理技术是用鸟粪石沉淀法回收磷,用氨汽提法回收氨氮。黑水的最佳处理方法是厌氧消化;灰水的最佳处理方法是人工湿地和BAF、MBR等好氧生物处理技术。     

德国污水污泥处理处置政策及磷回收技术解析与启示

德国于2017年10月3日通过了对《污水污泥条例》的修订,核心内容是要求从污水污泥或其焚烧灰中回收磷。按德国污水污泥处置的相关立法,只有符合《污水污泥条例》《肥料条例》的限值要求,才允许污水污泥排放并进行土壤利用。分析了德国磷的供需矛盾及磷回收潜力及方法,介绍了德国经济型磷回收情况。从德国污水污泥处置途径的发展来看,由于协同焚烧投资相对较低,在德国曾是发展的主流方向,但随着《污水污泥条例》的执行,德国将逐步转向单独焚烧处理,到2029年必将基本废弃协同焚烧处理方式。德国污水污泥处理处置经验可为我国污水污泥的处理处置提供有益借鉴。     

污水处理厂污泥水处理技术研究进展

污泥水是指污水处理厂污泥浓缩、消化、脱水等环节产生的污水。污泥水独立对处理提升污水处理效率,实现污水处理厂稳定运行具有重要意义。污泥水悬浮物和总磷去除的关键问题是根据其水质特性确定合适的混凝剂和低成本的除磷剂。利用污泥水的高氨氮实现侧流富集硝化菌强化主流污水处理系统硝化能力在污水处理厂升级改造中具有良好的应用前景。短程硝化反硝化和厌氧氨氧化工艺能够有效解决污泥水脱氮存在的碳源不足的问题。随着深度脱水技术在国内的大规模应用,利用深度脱水污泥水补充污泥水脱氮所需的碱度和碳源,以及除磷所需的钙源能够大幅度降低污泥水脱氮除磷的运行成本。     

反硝化除磷机理及影响因素研究

反硝化除磷技术的应用能起到减少曝气量,节约耗能、减少污泥量和节约成本;特别是能解决我国南方水体C/N、C/P偏低等问题,对现代污水处理起到了积极的作用。该文主要介绍反硝化聚磷菌的除磷理论、机理,重点分析反硝化除磷工艺对碳源、硝酸盐和亚硝酸盐、温度、pH和ORP、污泥龄、水力停留时间等各种影响因素研究,并分析了该反硝化除磷技术的研究进展。     

剩余污泥中磷释放技术研究进展

剩余污泥是污水生物处理的副产物，以活性微生物为主，其中含有大量的磷源。为了促使污泥中磷的释放并实现回收利用，综述了剩余污泥中磷释放的物理、化学和生物处理三类方法，对各种处理方法的基本原理、适宜操作参数及优缺点进行了分析总结，分析表明：物理和化学处理方法可以达到快速释磷的效果，但物理法操作条件相对较激烈、化学法药剂需求量大；将厌氧发酵法与物理或化学法相结合，提高磷释放和回收效率是较为理想的方式之一。最后提出研究预处理释磷过程中性质较缓和的化学物质或非激烈的物理处理方式，及研究污泥中有机物的转化对磷释放和磷回收机制的影响将是今后的研究重点。     

A2/O工艺中的反硝化除磷现象

将反硝化除磷菌应用于北京市某污水处理厂的A2/O工艺中,对其整个冬季水质进行监测,研究了A2/O工艺中的反硝化除磷现象。结果表明:污水处理厂污泥的除磷性能逐渐增强,存在明显的反硝化除磷现象;随着除磷能力的增强,反硝化除磷量与总除磷量之比逐渐增大;在低碳源城市污水处理中,反硝化除磷能在一定程度上缓解碳源不足的问题。     

上海曲阳污水处理厂改造工艺及应用

针对上海曲阳污水处理厂达标改造工程的特点和要求,对污水处理工艺采用具有自主知识产权的双污泥脱氮除磷处理技术(PASF)、污泥处理和生物滤池臭气处理方案、工艺流程和设计参数进行介绍,对工程实施和运行情况进行分析,为全国污水处理厂达标改造提供参考.     

污泥活性炭制备及应用

城市污水处理厂的污泥含有大量的有机物和有毒有害物质,如果不能妥善处理会污染环境并浪费资源。活性炭因其自身多孔材料可以去除污水中有毒有害物质,广泛应用于污水治理方向。总结了污泥活性炭的不同制备方法,探究了污泥活性炭的吸附反应模型,同时讨论了污泥活性炭在不同性质的污水处理方面的应用现状,概述了污泥活性炭在污水处理行业、大气治理行业以及土壤修复行业的应用。     

Recovering phosphorus as struvite from the digested swine wastewater with bittern as a magnesium source

Recovering nitrogen and phosphorus through struvite (MgNH4PO4 6H2O) crystallization from swine wastewater has gained increasing interest. However, swine wastewater contains complex compositions, which may hinder the formation of struvite crystal and affect the purity of the precipitates by forming other insoluble minerals. In this work, experiments were carried out to evaluate struvite precipitation in the anaerobically digested swine wastewater, with dosing bittern as a low-cost magnesium source. Exceeded 90% phosphate removal and 23-29% ammonium reduction were obtained. FTIR, XRD and mass balance analysis were combined to analyze the species of precipitated minerals. Results showed that the precipitates were struvite, mixed with amorphous calcium phosphate (ACP) and brucite. The presence of Ca2+ diminished the percentage of struvite and gave rise to ACP formation. Controlling pH below 9.5 and bittern dosage above 1% (w/w) could inhibit ACP precipitation and harvest a highly pure struvite crystal product.     

Recovery of phosphorus and aluminium from sewage sludge ash by a new wet chemical elution process (SESAL-Phos-recovery process)

The potential of a new wet chemical process for phosphorus and aluminium recovery from sewage sludge ash by sequential elution with acidic and alkaline solutions has been investigated: SESAL-Phos (sequential elution of sewage sludge ash for aluminium and phosphorus recovery). Its most innovative aspect is an acidic pre-treatment step in which calcium is leached from the sewage sludge ash. Thus the percentage of alkaline soluble aluminium phosphates is increased from 20 to 67%. This aluminium phosphate is then dissolved in alkali. Subsequently, the dissolved phosphorus is precipitated as calcium phosphate with low heavy metal content and recovered from the alkaline solution. Dissolved aluminium is recovered and may be reused as a precipitant in wastewater treatment plants.     

Applications and limitations of ADM 1 in municipal wastewater solids treatment.

The ADM 1 model has been implemented in a steady-state whole wastewater plant simulator. The ADM 1 model has been in use with good success for approximately 2 years on a wide range of wastewater treatment facilities. However, a number of modifications were necessary to allow it to be used in the context of municipal wastewater treatment. It was found that the model's use was greatly simplified if used in conjunction with a larger plant simulator to assist in the feed fractionation. It was also found that a better fit to actual operating data was achieved if some of the slowly biodegradable particulate fraction was partitioned into ADM particulate fractions other than the composite fraction. Another significant limitation of the model is in the absence of phosphorus modeling. The ADM model needs to have phosphorus handling for all the relevant fractions, and needs to include the handling of inorganic reactions such as struvite precipitation and metal phosphate/metal hydroxide precipitation. Activity effects on chemical equilibria are significant when considering phosphorus. Also of importance in wastewater treatment is the fate of sulfur compounds. This includes the generation of H2S in the digester gas and the fate of the sulfur species in the digested sludge (as a predictor of odour-generating potential).     

Effects of organic and inorganic acids on phosphorus release from municipal sludge.

This paper reports on the effects of inorganic acids (sulphuric acid, hydrochloric acid, nitric acid) and organic acids (citric acid, oxalic acids) for phosphorus recovery from sludge and struvite precipitation results. It was observed that both inorganic acid and organic acids were effective at phosphorus release. The studies on precipitation of released phosphorus from sludge as magnesium ammonium phosphate (struvite) were also done using nitric and oxalic acids. Phosphorus and heavy metals of leachate were analyzed before and after precipitation. It was observed that heavy metal concentrations in the extracted samples decrease after precipitation. Precipitation was accomplished by using extract derived with nitric acid; however, in oxalic acid applications, it was not achieved. When the chemical constituents of the dried material were examined oxygen, sodium and nitrogen were found to be the major elements.     

Phosphorus recovery--an overview of potentials and possibilities.

The endeavour towards a sustainable society has led to an interest in the recovery and recirculation or reuse of phosphorus from wastewater among environmentalists and politicians. In a recent interdisciplinary investigation commissioned by the Swedish Environmental Protection Agency, an attempt was made to evaluate different possibilities to recover phosphorus from wastewater or its fractions; systems based on source separation of urine or of combined toilet wastes, on the extraction of phosphorus from sludge, from ashes after incineration of sludge or from wastewater as well as the direct recirculation of hygienised digested and dewatered sludge were studied. Aspects like technology, environmental effects, resource economy, economy, markets, organisational aspects and user aspects were studied. In this overview the potential and possibility to recover and recirculate phosphorus from wastewater is discussed, mainly based on the findings in this investigation.     

Towards a complete recycling of phosphorus in wastewater treatment--options in Germany

Global reserves of mineral phosphorus are finite and the recycling of phosphorus from wastewater, a significant sink for phosphorus, can contribute to a more sustainable use. In Germany, Switzerland, and the Netherlands, an increasing percentage of municipal sewage sludge is incinerated and the contained phosphorus is lost. This paper reviews current technologies and shows that a complete phosphorus recovery from wastewater is technically feasible. Depending on the composition of the sewage sludge ash (SSA), there are various options for phosphorus recovery that are presented. Iron-poor SSAs can be used directly as substitute for phosphate rock in the electrothermal phosphorus process. SSAs with low heavy metal contents can be used as fertilizer without prior metal elimination. Ashes not suitable for direct recycling can be processed by thermal processes. Operators of wastewater treatment plants can additionally influence the ash composition via the selection of precipitants and the control of (indirect) dischargers. This way, they can choose the most suitable phosphorus recovery option. For sewage sludge that is co-incinerated in power plants, municipal waste incinerators or cement kilns phosphorus recovery is not possible. The phosphorus is lost forever.     

Energy and phosphorus recovery from black water

Source-separated black water (BW) (toilet water) containing 38% of the organic material and 68% of the phosphorus in the total household waste (water) stream including kitchen waste, is a potential source for energy and phosphorus recovery. The energy recovered, in the form of electricity and heat, is more than sufficient for anaerobic treatment, nitrogen removal and phosphorus recovery. The phosphorus balance of an upflow anaerobic sludge blanket reactor treating concentrated BW showed a phosphorus conservation of 61% in the anaerobic effluent. Precipitation of phosphate as struvite from this stream resulted in a recovery of 0.22 kgP/p/y, representing 10% of the artificial phosphorus fertiliser production in the world. The remaining part of the phosphorus ended up in the anaerobic sludge, mainly due to precipitation (39%). Low dilution and a high pH favour the accumulation of phosphorus in the anaerobic sludge and this sludge could be used as a phosphorus-enriched organic fertiliser, provided that it is safe regarding heavy metals, pathogens and micro-pollutants.     

Municipal sludge management and disposal in South Korea: status and a new sustainable approach.

Based on figures from 2002, 5216 ton/d of the municipal sludge is produced from 184 large municipal wastewater treatment plants in 111 cities with total treatment capacity of 19,229,745 m3/d. Even though the large amount of sludge disposal has depended greatly on ocean disposal and landfills until recently, the fraction of sludge reuse has gradually increased from 2.7% to 7%, since 1991. Due to a need of resources recovery from the sludge, high cost requirement of incineration and legislative regulation, recent new research is mainly focused on resources recovery and its reuse from the municipal sludge, such as high performance acid fermenter with pathogen reduction, crystallization (struvite and hydroxyapatite) using waste lime, cofermentation of municipal sludge with food waste, aerobic composting with P crystallization, vermistabilization, lime treatment, etc. Current research and practical activities with some efforts for the new technical development as well as environmental law and regulation are reviewed.     

A study of NH3-N and P refixation by struvite formation in hybrid anaerobic reactor.

This research is concerned with the removal of ammonia nitrogen and phosphorus in foodwaste by crystallization. Reductions have been achieved by struvite formation after the addition of magnesium ions (Mg2+). Magnesium ions used in this study were from magnesium salts of MgCl2. The results of our analysis using scanning electron microscopy and energy dispersive X-ray analysis showed that the amount of struvite in precipitated sludge grew enough to be seen with the naked eye (600-700 microm). EDX analysis also showed that the main components of the struvite were magnesium and phosphorus. NH3-N removal efficiency using MgCl2 was 67% while PO4-P removal efficiency was 73%. It was confirmed that nitrogen and phosphorus could be stabilized and removal simultaneously through anaerobic digestion by Mg, NH3 and PO4-P, which were necessary for struvite formation.     

Phosphorus recycling in sewage treatment plants with biological phosphorus removal.

In this paper, phosphorus balances are calculated for the wastewater purification and sludge treatment stages for wastewater treatment plants (WWTPs) applying Enhanced Biological Phosphorus Removal (EBPR). The possible P-recovery potential is then estimated and evaluated regarding different locations along the process of wastewater purification and sludge treatment, taking the different phosphorus bonding forms into account. Caused by the more favourable bonding forms in the excess sludge as well as possibly also in the sludge ash a recovery of the phosphorus seems especially favoured for WWTPs with EBPR. The processes available for a P recycling are named, and special regard is given to the Phostrip-process, which is a possible recycling process already tested in practice. Further R&D demand consists in basic research regarding disintegration, fermentation or acidic total digestion of excess sludge followed by phosphorus precipitation including separation of the precipitates, MAP-precipitation and separation from digested sludge and on the ability to extract phosphorus and heavy metals from sewage sludge ash. These investigations are a precondition to enable purposeful process developments. At the present state the cost of recycled phosphorus earned from wastewater, sludge and ash, respectively, are a multiple higher than the costs for raw phosphate taking into account the suitable processes. Thus, up to now no phosphorus recycling with a defrayal of costs is possible. The future importance of phosphorus recycling will depend on the market price for raw phosphate, the recycling costs and, furthermore, on the general political framework.