Automatic control and remote monitoring system for biological nutrient removal on small wastewater treatment plants in Korea.

Many small-size wastewater treatment plants in Korea's rural communities are designed to remove organic and suspended matter only, and they generally show a large fluctuation in the influent loading compared to municipal wastewater treatment plants (MWWTPs). They also have no professional engineers stationed for efficient operation against mechanical breakdown. For those reasons, the wastewater treatment plants have low efficiency in treatment of nitrogen and phosphorus as well as organic matter. In order to solve those problems, this study developed an automatic control system and RMS (remote monitoring system), which can keep efficiency stable despite any change in the small plants' loading rates and are capable of removing nutrient materials such as nitrogen or phosphorus. According to the results of the Experimental SBR system of the automatic control program, complete nitrification was made under oxic conditions and denitrification occurred as NO3-N concentration decreased by 0.5 mg/l in anoxic conditions and excellent nitrogen removal efficiency was seen generally. The Experimental SBR system created "phosphate release and uptake" effectively and displayed phosphate-removing efficiency up to more than 80% as the concentration of effluent was kept low by 0.4 mg/l. RMS developed in this study transmits a plant's data and operation states to clients in remote locations in real-time interval through the Internet. Therefore, although you are in a remote location, it allows you to see if a plant is properly operated or there is any breakdown.     

Application of remote monitoring and automatic control system using neural network for small wastewater treatment plants in Korea.

For this study, an automatic control system has been developed by using a neural network and internet-based remote monitoring system for efficient operation of plants that have a serious variance of influent loading and have difficulties in appropriate maintenance, just like small wastewater treatment plants in Korea. In the control algorithm, ORP was used as the main sensor for control. At the point where the ORP value was judged to reach the "nitrate knee" of denitrification and phosphorus release, ORP indicated the state of lower saturation read by the neural network and then changed the operating condition from the reduction state to the oxidation state. For example, if ORP indicates the state of higher saturation at the point of "nitrogen breakpoint" or "ammonia valley" of nitrification, the neural network reads it and cuts off the oxygen supply and mixing. The dORP data have been used as one of the main input for the neural network. After the operation of lab-scale cyclic aeration process using an automatic control system, it has been found that regardless of loading variance, more than 95% of organic matters and more than 60% of nitrogen and phosphorus have been removed. Assuming that an internet-connected computer and a basic web browser are available, this study has developed a remote monitoring system that can monitor the operating status of small plants or any troubles with them.     

污水处理系统的集成控制策略研究

以实现河流水质目标为前提,充分利用河流纳污能力,根据不同环境与气候条件调节污水处理厂运行状况和排水管网的污水排放量,可有效保护河流生态质量。基于城市污水处理系统集成仿真平台,提出了4种以河流水质为目标的城市污水处理系统集成控制方案,通过对排水管网和污水处理厂的协调控制,实现了河流水质的改善。仿真结果验证了集成控制策略的有效性。     

An intelligent visualisation and decision support system for decentralised wastewater treatment plants.

Current sanitation concepts of decentralised wastewater treatment and reuse raise the issue of monitoring and maintenance of such systems. To guarantee high quality of the recycled water, systems with high requirements concerning process technology are essential. With increasing numbers of decentralised treatment systems spread over far distances it will become more and more impossible and uneconomic to have expert personnel on site. Therefore, new visualisation and intelligent information systems are necessary. The paper describes the structure and 3D-demonstrations as a base for information visualisation. Up-to-date visualisation techniques, facilitating the cognition of context-adapted information, make it possible to maximise the amount of information presented to the user without overwhelming her or him. Concerning diagnosis and decision support systems in the domain of wastewater treatment, several interesting approaches are presented, estimating their applicability for decentralised wastewater treatment systems. The intelligent decision support system presented here consists of a combined ontology- and case-based reasoning system in addition to a process monitoring system. It is responsible for plausibility checks, error diagnosis, solution proposals, and optimisation suggestions.     

Fault detection for control of wastewater treatment plants.

Interest in real-time model-based control is increasing as more and more facilities are being asked to meet stricter effluent requirements while at the same time minimizing costs. It has been identified that biological process models and automated process control technologies are being used at wastewater treatments plants throughout the world and that great potential for optimising biotreatment may exist with the integration of these two technology areas. According to our experience, wastewater treatment plants are indeed looking for ways to successfully integrate their modelling knowledge into their process control structure; however, there are practical aspects of this integration that must be addressed if the benefits of this integration are to be realised. This paper discusses the practical aspects of monitoring, filtering and analysing real sensor data with an aim to produce a reliable real-time data stream that might be used within a model-based control structure. Several real case study examples are briefly discussed in this paper.     

Knowledge-based fuzzy system for diagnosis and control of an integrated biological wastewater treatment process.

A supervisory expert system based on fuzzy logic rules was developed for diagnosis and control of a laboratory- scale plant comprising anaerobic digestion and anoxic/aerobic modules for combined high rate biological N and C removal. The design and implementation of a computational environment in LabVIEW for data acquisition, plant operation and distributed equipment control is described. A step increase in ammonia concentration from 20 to 60 mg N/L was applied during a trial period of 73 h. Recycle flow rate from the aerobic to the anoxic module and bypass flow rate from the influent directly to the anoxic reactor were the output variables of the fuzzy system. They were automatically changed (from 34 to 111 L/day and from 8 to 13 L/day, respectively), when new plant conditions were recognised by the expert system. Denitrification efficiency higher than 85% was achieved 30 h after the disturbance and 15 h after the system response at an HRT as low as 1.5 h. Nitrification efficiency gradually increased from 12 to 50% at an HRT of 3 h. The system proved to react properly in order to set adequate operating conditions that led to timely and efficient recovery of N and C removal rates.     

Tracking influent inorganic suspended solids through wastewater treatment plants.

From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank (PST), fully aerobic or N removal activated sludge (AS) and anaerobic and aerobic sludge digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through primary sludge anaerobic digestion, activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant (WWTP) unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organisms (OHO) biomass contributes to the ISS flux by differing amounts depending on the active fraction of the VSS solids at that stage.     

Dynamic monitoring system for full-scale wastewater treatment plants.

This paper proposes a new process monitoring method using dynamic independent component analysis (ICA), ICA is a recently developed technique to extract the hidden factors that underlie sets of measurements, whereas principal component analysis (PCA) is a dimensionality reduction technique in terms of capturing the variance of the data. Its goal is to find a linear representation of non-Gaussian data so that the components are statistically independent. PCA aims at finding PCs that are uncorrelated and are linear combinations of the observed variables, while ICA is designed to separate the ICs that are independent and constitute the observed variables. The dynamic ICA monitoring method is applying ICA to the augmenting matrix with time-lagged variables. The dynamic monitoring method was applied to detect and monitor disturbances in a full-scale biological wastewater treatment (WWTP), which is characterized by a variety of dynamic and non-Gaussian characteristics. The dynamic ICA method showed more powerful monitoring performance on a WWTP application than the dynamic PCA method since it can extract source signals which are independent of time and cross-correlation of variables.     

An integrated electro-chemical and natural treatment system for industrial water pollution control.

Experiments were conducted to test the feasibility of applying an integrated electro-chemical (EC) and natural treatment system for treatment of some industrial wastewaters. The EC process was found to be very effective in removing lead, a model heavy metal from some wastewaters. Within 20 minutes of operation time, 5 to 10 A of electric current and specific surface area of electrode of 46.51 m2/m3, the lead concentrations in the wastewaters were reduced from 35-100 mg/l to less than 1 mg/l. Based on a kinetic model developed from the experimental data, the important parameters for the EC process were found to be electric current, specific surface area of electrode, and operation time. From scanning electron microscopic and X-ray diffractometric (XRD) analysis, the EC sludge samples were found to compose mainly of maghemite (Fe2O3), magnetite (Fe3O4), and laurionite (PbClOH), suitable for disposal to secure landfills. Two pilot-scale constructed wetlands (CW) in series, a model natural treatment system, were employed to treat wastewaters of an industrial estate in Thailand. At organic loading rates of 57-140 kg BOD/hectare-year, these constructed wetlands were able to reduce BOD from 90 to 4 mg/l, while suspended solids, total nitrogen and total phosphorus were reduced from 100 to 10 mg/l, 24 to 4.6 mg/l and 7 to 1.5 mg/l, respectively, during the summer season. These results demonstrated technical feasibility of CW in removing organic and other pollutants contained in this industrial wastewater.     

污水处理厂的安全自控系统

随着污水处理行业的快速发展,污水处理厂安全越来越成为工艺稳定运行的关键.针对控制系统本身的安全性及对相应控制设备和工艺的安全性,提出了污水处理厂的安全自控系统原则.并以实际自控系统为例,说明安全自控系统的组成及实现.     

Biosensor-based control of nitrification inhibitor in municipal wastewater treatment plants.

The effect of potassium cyanide (KCN) on nitrification processes in municipal wastewater treatment plants was studied by batch nitrification tests, which indicated that nitrification processes tend to be inhibited at a lower KCN concentration than the present discharge standard to sewerage. The experiment of the biosensor using nitrifying bacteria was also conducted for continuous monitoring of nitrification inhibitor in influent wastewater, and demonstrated that the biosensor can detect KCN at as low as EC10 of the abovementioned batch nitrification test. Moreover, to determine the effectiveness of application of the biosensor to avoid the impact of KCN due to an accidental spillage in a sewerage system, KCN was intentionally injected into the experimental models of activated sludge process equipped both with and without the biosensor. The model with the biosensor that could detect KCN could divert the wastewater including KCN to a refuge tank, which resulted in the avoidance of upset of the activated sludge process. On the other hand, the model without the biosensor was upset in the nitrification process due to KCN. Such differences demonstrate the effectiveness of the biosensor applied to countermeasures of an accidental spillage of toxic chemicals to avoid upset of nitrification in municipal wastewater treatment plants.     

An integrated modelling concept for immission-based management of sewer system, wastewater treatment plant and river.

Today's planning standards deal with the individual urban drainage components (sewer system, wastewater treatment plant and receiving water) separately, i.e. they are often designed and operated as single components. As opposed to this, an integral handling considers the drainage components jointly. This novel approach allows a holistic and more sustainable planning of urban drainage systems. This paper presents an integrated modelling concept. The aim is to analyse fluxes through the total wastewater system and to integrate pollution-based control in the upstream direction, that is, e.g., managing the combined water retention tanks as a function of state variables in the WWTP or the receiving water. All models of the different subsystems are based on the Activated Sludge Model (ASM) concept of IWA, including River Water Quality Model No. 1 (RWOM). Simulations can be done in truly parallel mode using the simulation environment SIMBA. The integrated modelling concept is applied to the river Dhuenn and the urban wastewater system of the municipality of Odenthal (Germany). An optimised operation of the system using RTC proves to be a very effective measure.     

An integrated approach for improving the wastewater discharge and treatment systems

Since treatment plants have been built all over Germany during the last decades, the water quality of receiving streams has been improved remarkably. But there are still a lot of quality problems left, which are caused e.g. by combined sewer overflows (CSO), treatment plant effluents or rainwater discharges from separate sewer systems. At present different efforts are undertaken to control sewer systems in order to improve the operation of urban drainage systems or more generally, design processes. The Emschergenossenschaft and Lippeverband (EG/LV) are carrying out research studies, which are focusing on a minimization of total emissions from sewer systems both from wastewater treatment plant (WWTP) effluents and from CSO. They consider dynamic interactions between rainfall, resultant wastewater, combined sewers, WWTP and receiving streams. Therefore, in an advanced wastewater treatment, a model-based improvement of WWTP operation becomes more and more essential, and consequently a highly qualified operational staff is needed. Some aspects of the current research studies are presented in this report. The need and the use of an integrated approach to combine existing model components in order to optimize dynamic management of combined sewer systems (CSS) with a benefit for nature are outlined.     

Optimisation and control of the inflow to a wastewater treatment plant using integrated modelling tools

The present paper describes the Heisingborg Pilot Project, a part of the Technology Validation Project: “Integrated Wastewater” (TVP) under the EU Innovation Programme. The objective of the Heisingborg Pilot Project is to demonstrate implementation of integrated tools for the simulation of the sewer system and the wastewater treatment plant (WWTP), both in the analyses and the operational phases. The paper deals with the programme for investigating the impact of real time control (RTC) on the performance of the sewer system and wastewater treatment plant As the project still is in a very early phase, this paper focuses on the modelling of the transport of pollutants and the evaluation of the effect on the sediment deposition pattern from the implementation of real time control in the sewer system.     

Winery and distillery wastewater treatment by anaerobic digestion.

Anaerobic digestion is widely used for wastewater treatment, especially in the food industries. Generally after the anaerobic treatment there is an aerobic post-treatment in order to return the treated water to nature. Several technologies are applied for winery wastewater treatment. They are using free cells or flocs (anaerobic contact digesters, anaerobic sequencing batch reactors and anaerobic lagoons), anaerobic granules (Upflow Anaerobic Sludge Blanket--UASB), or biofilms on fixed support (anaerobic filter) or on mobile support as with the fluidised bed. Some technologies include two strategies, e.g. a sludge bed with anaerobic filter as in the hybrid digester. With winery wastewaters (as for vinasses from distilleries) the removal yield for anaerobic digestion is very high, up to 90-95% COD removal. The organic loads are between 5 and 15 kgCOD/m3 of digester/day. The biogas production is between 400 and 600 L per kg COD removed with 60 to 70% methane content. For anaerobic and aerobic post-treatment of vinasses in the Cognac region, REVICO company has 99.7% COD removal and the cost is 0.52 Euro/m3 of vinasses.     

硫酸盐还原菌及其在废水厌氧治理中的应用

硫酸盐还原菌(SRB)在废水处理方面有独特的优势,在厌氧环境中能以硫酸盐作为电子受体降解有机污染物。本文阐明了SRB处理废水中污染物的机理,综述了国内外利用SRB处理重金属离子废水、含硫酸盐有机废水和酸性矿山废水的研究进展。最后总结了目前在工程应用方面尚存在的问题。     

A comparison of continuous flow and sequencing batch reactor plants concerning integrated operation of sewer systems and wastewater treatment plants.

Integrated operation strategies for combined sewer and WWTP are becoming more and more popular because of numerous benefits. One can find many examples in literature, but many of these studies deal with partly fictitious systems and/or were accomplished within the planning. Hence most of these studies do not have to deal with the restrictions given by already built constructions. The authors, who worked on several integrated projects, will discuss the requirements of SBR and CFR plants concerning an implementation of integrated operation.     

High-rate anaerobic wastewater treatment: diversifying from end-of-the-pipe treatment to resource-oriented conversion techniques.

Decades of developments and implementations in the field of high-rate anaerobic wastewater treatment have put the technology at a competitive level. With respect to sustainability and cost-effectiveness, anaerobic treatment has a much better score than many alternatives. Particularly, the energy conservation aspect, i.e. avoiding the loss of energy for destruction of organic matter, while energy is reclaimed from the organic waste constituents in the form of biogas, was an important driver in the development of such systems. Invoked by the present greenhouse alert, the energy involved is nowadays translated into carbon credits, providing another incentive to further implement anaerobic technology. Anaerobic conversion processes, however, offer much more than cost-effective treatment systems. Selective recovery of metals, effective desulphurization, recovery of nutrients, reductive detoxification, and anaerobic oxidation of specific compounds are examples of the potentials of anaerobic treatment. This paper presents a survey on the state of the art of full-scale anaerobic high-rate treatment of industrial wastewaters and highlights current trends in anaerobic developments.     

Modeling of anaerobic treatment of wastewater in ponds.

A mathematical model to simulate the performance of anaerobic ponds was developed incorporating both settling of particulate components and the biological anaerobic digestion process. The biological activity includes solubilization of particulate organic matter; methanogenesis and the sulphate reduction process. The model considers that an anaerobic pond comprises a series of equal size columns. Each column has three compartments viz. liquid layer, active sediment layer and inert sediment layer. The existence of organic matter and sulphate removal mechanisms both in the bulk as well as sediment layer of the ponds and the exchange of the soluble components between the layers has been included in the model. The model was transferred to a computer program using VisSim Basic software. The model was verified by comparing simulated results with full-scale as well as with laboratory-scale anaerobic pond performance data. A good agreement between the simulated and the observed pond performance was achieved.     

Occurrence and control of filamentous bulking in aerated wastewater treatment plants of the French paper industry.

The occurrence of filamentous bacteria was investigated in 15 French pulp and paper activated sludge wastewater treatment plant (WWTP). Large filamentous populations were present in most of the plants. Identification carried out with conventional methods based on morphological features and staining techniques showed that the four main filamentous bacteria encountered in these industrial WWTP and responsible for bulking belong to the genera Thiothrix sp., Type 021 N, Haliscomenobacter hydrossis and Type 0092. During two years a specific survey was performed for three of these WWTP showing recurrent bulking phenomena. Data from WWTP performance, chemical data and filaments characterization were compared to correlate the presence of specific filaments with process operating conditions.