Design of a modern automatic control system for the activated sludge process in wastewater treatment

The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.

Advances in Control Technologies for Wastewater Treatment Processes:Status, Challenges, and Perspectives

This paper presents a thorough review of control technologies that have been applied to wastewater treatment processes in the environmental engineering regime in the past four decades. It aims to provide a comprehensive technological review for both water engineering professionals and control specialists, giving rise to a suite of up-to-date pathways to impact this field in light of the classified technology hubs. The assessment was conducted with respect to linear control, linearizing control,nonlinear control, and artificial intelligence-based control. The application domain of each technology hub was summarized into a set of comparative tables for a holistic assessment. Challenges and perspectives were offered to these field engineers to help orient their future endeavor.

MULTI-LAYER PIEZOELECTRIC ACTUATOR AND ITS APPLICATION IN CONTROLLABLE CONSTRAINED DAMPING TREATMENT

A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control. The governing equation of the system is derived based on the constitutive equations of elastic, viscoelastic and piezoelectric materials, which shows that the magnitude of control force exerted by multi-layer piezoelectric actuator is the quadratic function of the number of piezoelectric laminates used but in direct proportion to control voltage. This means that the multi-layer actuator can produce greater actuating force than that by piezoelectric laminate actuator with the same area under the identical control voltage. The optimal location placement of the multi-layer piezoelectric actuator is also discussed. As an example, the hybrid vibration control of a cantilever rectangular thin-plate is numerically simulated and carried out experimentally. The simulated and experimental results validate the power of multi-layer piezoelectric actuator and indicate that the present hybrid damping technique can effectively suppress the low frequency modal vibration of the experimental thin-plate structure.

Application of an expert system using neural network to control the coagulant dosing in water treatment plant

The coagulation process is one of the most important stages in water treatment plant, which involves many complex physical and chemical phenomena. Moreover, coagulant dosing rate is non-linearly correlated to raw water characteristics such as turbidity, conductivity, PH, temperature, etc. As such, coagulation reaction is hard or even impossible to control satisfactorily by conventional methods. Based on neural network and rule models, an expert system for determining the optimum chemical dosage rate is developed and used in a water treatment work, and the results of actual runs show that in the condition of satisfying the demand of drinking water quality, the usage of coagulant is lowered.

Overview on Treatment and Control Technology for Water Eutrophication

Eutrophication is one of the important reasons for water pollution and is also the problem for water pollution treatment at home and abroad. This article takes an overview on various technical methods and their characteristics applicable for treatment and control of water eutrophication from the aspects of physics, chemistry, biochemistry and environmental factors regulation, and discusses the application and development trend for relevant technologies.

Performance Analysis of Automated Control System for Condenser Water Treatment Unit

The air conditioning system in the Umm Al-Qura University (Albdiya Campus) was conceived to be a district cooling by a remote chilled water plant. Recently, there are two chilled water plants in the university installed strategically to provide chilled water to all the academic and administrative buildings of the university through distribution network with total capacity approximately of 12,000 tons of refrigeration. The plants were built based on cooling towers with open water cycle as heat rejection system. Water treatment chemicals has been used to protect the cooling systems from corrosion, scaling and microbiological fouling accompanied with dissolved and suspended water impurities. Different methods are being used to determine and control the treatment chemical concentrations and system performance indicators. Traditional chemical controller has drawback of indirect measurements and set points. The purpose of this paper is to present a solution to overcome the problems of traditional and conventional chemical treatment and control sys-tems. Central cooling plant number (1) assigned to perform experimental setup using new chemical treatment technology. Advanced automatic chemical treatment controller installed on condensers (1, 2 and 3), and certain key performance indicators were selected and monitored such as chemical and water consumption, power, energy saving, and maintaining system integrity and efficiency. Satisfactory results were obtained in terms of performance and cost of operation.

Modeling and Control of pH in Pulp and Paper Wastewater Treatment Process

Pulp and paper industry is responsible for large discharge of highly polluted effluents, which often be treated by biological treatment process. For biological treatment system, pH is an important environmental factor that can influence the activity of microorganisms. In general, the optimal pH for aerobic processes is around neutral pH (7_7.8) and for the anaerobic process is between 6.8_7.2. The control of pH is a difficult link in the biological treatment system due to its nonlinearity and large time-delay. Aiming at the difficult point in the pH control of the biological wastewater treatment system, a mathematical model of pH control is estab-lished in the essay. On this basis, a traditional PID control and a cascade control are adopted to carry out simulation and comparison with MATLAB. The results show that the cascade control has better comprehen-sive effect in terms of response speed, stability and disturbance resistance.

Microbial safety control of compost material with cow dung by heat treatment

Various kinds of pathogenic bacteria derived from the intestinal tract of animals exist in compost material like cow dung. In order to sterilize the pathogenic bacteria completely in compost material, the cow dung was put into a heat treatment machine in pilot plan, and harmless condition in short time was examined. The results indicated, pathogenic indicator bacteria such as coliform bacteria, fecal coliform, Escherichia coli and salmonella were all 106 cfu/g dw at the beginning, died rapidly when cow dung temperature rose to above 50~C, and not detected at 54-68~C for 6-24 h heat treatment. Coliform bacteria and salmonella in heated cow dung were not detected by re-growth culture and enrichment culture examination. Moreover, it was hardly influenced on the fermentation ability of composting microbe, organic decomposition bacteria. During heat treatment, the mesophile decreased rapidly and the thermophile stabilized or increased, and the most of composting microbe were bacillus in cow dung by fluorescence microscope, this indicated that bacillus was dominator and composting microbe in composting process.

Modeling Rift Valley Fever with Treatment and Trapping Control Strategies

We consider a rift valley fever model with treatment in human and livestock populations and trapping in the vector (mosquito) population. The basic reproduction number R 0 is established and used to determine whether the disease dies out or is established in the three populations. When R 0 ≤ 1, the disease-free equilibrium is shown to be globally asymptotically stable and the disease does not spread and when R 0 > 1, a unique endemic equilibrium exists which is globally stable and the disease will spread. The mathematical model is analyzed analytically and numerically to obtain insight of the impact of intervention in reducing the burden of rift valley fever disease’s spread or epidemic and also to determine factors influencing the outcome of the epidemic. Sensitivity analysis for key parameters is also done.

Effect of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with electronic control backwashing

Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors （SMBRs） operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR （CSMBR） while the other was dosed with powdered activated carbon （PAC） （PAC-amended SMBR, PSMBR）. The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d （576 h） was 5.87 L/h with average hydraulic residence time （HRT） of 5.97 h and that of PSMBR during a steady periodic state of 30 d （720 h） was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand （COD） removal efficiency of CSMBR was 89.29% with average organic loading rate （OLR） at 4.16 kg COD/（m^3.d） while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/（m^3.d）. COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry （300 mg/L）. Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.

Study of Water Treatment Residue Used as a Profile Control Agent

A large amount of residue from the water treatment process has gradually accumulated and thus caused serious environmental pollution in waterflood oilfields. The water treatment residue is a grey suspension, with a density of 1.08 g/cm^3, and mainly contains over 65% of light CaCO3, MgCO3, CaSO4, Fe2S3 and Ca（OH）2. This paper ascertains the effect of water treatment residue on core permeability and its application in oilfields. Coreflooding tests in laboratory were conducted in two artificial cores and one natural core. Core changes were evaluated by cast model image analysis, mercury injection method and scanning electron microscopy （SEM）. Fresh water was injected into another natural core, which was plugged with water treatment residue, to determine the effective life. The results indicate that the water treatment residue has a strongly plugging capability, a resistance to erosion and a long effective life, and thus it can be used as a cheap raw material for profile control. In the past 8 years, a total of 60,164 m^3 of water treatment residue has been used for profile control of 151 well treatments, with a success ratio of 98% and an effective ratio of 83.2%. In the field tests, the profile control agent increased both starting pressure and injection pressure of injectors, and decreased the apparent water injectivity coefficient, significantly improving intake profiles and lengthening average service life of injectors. 28,381 tons of additional oil were recovered from these corresponding oil wells, with economic benefits of ￥3,069.55×10^4 （RMB） and a remarkable input-output ratio of 8.6：1.

An Optimal Control Approach to Structured Treatment Interruptions for HIV Patients: A Personalized Medicine Perspective

Highly Active Antiretroviral Therapy (HAART) has changed the course of human immunodeficiency virus (HIV) treatments since its introduction. However, for many patients, long term continuous HAART is expensive and can include problems with drug toxicity and side effects, as well as increased drug resistance. Because of these reasons, some HIV infected patients will voluntarily terminate HAART. Some of these patients will also interrupt the continuous prescribed therapies for short or long periods. After discontinuing HAART, patients will usually experience a rapid increase in viral load coupled with an immediate decline in CD4+ counts. The canonical example of a patient undergoing unsupervised breaks in HAART is that of the “Berlin patient”. In this case, the patient was able to control viral load in the absence of treatment by cycling HAART on and off due to non-related infections. Due to this patient, interest in the use of structured treatment interruptions (STI) as a mechanism to regulate an HIV infection piqued. This paper describes an optimal control approach to determine STI regimen for HIV patients. The optimal STI was implemented in the context of the receding horizon control (RHC) using a mathematical model for the in-vivo dynamics of an HIV type 1 infection. Using available clinical data, we calibrate the model by estimating on a patient specific basis, a best estimable set of parameters using sensitivity analysis and subset selection. We demonstrate how customized STI protocols can be designed through the variation of control parameters on a patient specific basis.

Zishenpingchan granules for the treatment of Parkinson＇s disease：a randomized,double-blind,placebo-controlled clinical trial

Levodopa preparations remain the preferred drug for Parkinson＇s disease.However,long-term use of levodopa may lead to a series of motor complications.Previous studies have shown that the combination of levodopa and Zishenpingchan granules（consisting of Radix Rehmanniae preparata,Lycium barbarum,Herba Taxilli,Rhizoma Gastrodiae,Stiff Silkorm,Curcuma phaeocaulis,Radix Paeoniae Alba,Rhizoma Arisaematis,Scorpio and Centipede） can markedly improve dyskinesia and delay the progression of Parkinson＇s disease,with especially dramatic improvements of non-motor symptoms.However,the efficacy of this combination has not been confirmed by randomized controlled trials.The current study was approved by the Hospital Ethics Committee and was registered in the Chinese Clinical Trial Register（registration number：Chi CTR-INR-1701194）.From December 2014 to December 2016,128 patients（72 males and 56 females,mean age of 65.78 ± 6.34 years） with Parkinson＇s disease were recruited from the Department of Neurology of Longhua Hospital and Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine in China.Patients were equally allocated into treatment and control groups.In addition to treatment with dopamine,patients in treatment and control groups were given Zishenpingchan granules or placebo,respectively,for 24 weeks.Therapeutic efficacy was assessed using the Unified Parkinson＇s Disease Rating Scale,on-off phenomenon,Hoehn-Yahr grade,Scales for Outcomes in Parkinson＇s disease–Autonomic,Parkinson＇s disease sleep scale,Hamilton Anxiety Scale,Hamilton Depression Scale,Mini-Mental State Examination,and the Parkinson＇s Disease Quality of Life Questionnaire.Artificial neural networks were used to determine weights at which to scale these parameters.Our results demonstrated that Zishenpingchan granules significantly reduced the occurrence of motor complications,and were useful for mitigating dyskinesia and non-motor symptoms of Parkinson＇s disease.This combination of Chinese and Western medicine has the potential to reduce levodopa dosages,and no obvious side effects were found.These findings indicate that Zishenpingchan granules can mitigate symptoms of Parkinson＇s disease,reduce toxic side effects of dopaminergic agents,and exert synergistic and detoxifying effects.

基于ControlNet现场总线的高炉水站控制冗余控制系统

在对ControlLogix冗余系统硬件配置进行分析的基础上,设计了由ControlNet构成的冗余网络控制系统,并成功应用在某高炉水站控制系统中,并介绍了控制系统的硬件组成及软件编程。

Quantification and control of restrictive ecological factors in acidogenic de-sulfate bioreactor

As an artificial microbial ecosystem, acidogenic de sulfate bioreactor has high efficiency of sulfate removal. The restrictive ecological factors, including causing ecological factors, such as COD/SO 4 2- ratio and sulfate loading rate (Ns), and following ecological factors, such as pH value, oxidation reduction potential (ORP) and alkalinity (ALK) have significant effect on the ability and stability of acidogenic de sulfate bio reactor. Continuous flow and batch test were carried out to investigate the quantification and control of COD/SO 4 2- ratio, Ns, pH value, ORP and ALK in acidogenic de sulfate bioreactor supplied with molasses wastewater as sole organic carbon source and sodium sulfate as electron donor. It was demonstrated that In order to maintain high sulfate removal rate (SRR) of 80% to 90%, the restrictive factors should meet all the requirement as follows: k COD/ SO 4 2-  ratio≥2.0, Ns≤7.5 kg (m 3·d) -1 ,pH=5.7～6.2,ORP=-320～-420 mV and  ALK= 1 500～2 000 mg/L.

Knitted Microporous Polymers as Efficient Adsorbents for Wastewater Treatment: Effects of Skeleton Structure and Pore Distribution

Hyper-cross-linked microporous organic polymers(MOP) with controlled skeleton structure and pore distribution were prepared by Friedel-Crafts alkylation reaction. The hyper-cross-linked polymers(HCPs) produced by knitting aromatic functional groups posses the typical micro-and meso-porous composite structure and specific surface areas of up to 957 m^2·g^(-1). The obtained materials were evaluated as adsorbents for methylene blue(MB) and subjected to several batch adsorption tests to investigate the effects of adsorbent dosage, concentration of MB, temperature, and pH on MB removal. The maximum adsorbed capacity(q_m) of KAPs-Ph(381 mg·g^(-1), knitted using benzene) exceeded those of less mesoporous KAPs-PhPh_3(310 mg·g^(-1) knitted using 1,3,5-triphenylbenzene) and chloromethyl polystyrene resin(58 mg·g^(-1)). Moreover, KAPs-Ph could be regenerated by Soxhlet extraction with ethanol and reused for up to 15 times with minimal loss of adsorption capacity. The results illustrate that adsorption performance can be improved by controlling the pore structure of the adsorbing materials, and KAPs-Ph has a potential application values for the industrial removal of organic dyes from wastewater.

High value of controlled attenuation parameter predicts a poor antiviral response in patients with chronic hepatits B

BACKGROUND: Controlled attenuation parameter (CAP) is a non-invasive method for diagnosing hepatic steatosis based on vibration-controlled transient elastography. The objective of this study was to investigate the effect of high value of CAP on antiviral therapy in patients with chronic hepatitis B (CHB). METHODS: Patients with CHB receiving enticavir for initial antiviral therapy were studied; they were divided into the high CAP group and normal CAP group at baseline according to the CAP values. The effect of the antiviral therapy between the two groups were compared at week 12, 24 and 48. Patients with high CAP value at baseline were divided into three subgroups, mild, moderate and severe elevation; the therapeutic response were compared among patients with normal CAP and subgroups of patients with elevated CAP. RESULTS: A total of 153 patients were enrolled. Among them, 63 were in the high CAP group and 90 in the normal CAP group. Patients with high CAP had lower rates of ALT normalization and HBV DNA clearance in response to antiviral therapy compared with those with normal CAP at week 12, 24 and 48. Further analysis showed that the rate of ALT normalization in patients with mildly and moderately elevated CAP were significant lower than those with normal CAP at week 12 and 24; while the difference was not significant between the patients with normal CAP and those with severely elevated CAP. The rate of HBV DNA clearance was significantly lower in patients with severely elevated CAP compared with those with normal CAP at week 12, 24 and 48. CONCLUSION: CHB patients with high CAP had poor response to antiviral therapy.

Automatic control strategy for step feed anoxic/aerobic biological nitrogen removal process

Control of sludge age and mixed liquid suspended solids concentration in the activated sludge process is critical for ensuring effective wastewater treatment. A nonlinear dynamic model for a step-feed activated sludge process was developed in this study. The system is based on the control of the sludge age and mixed liquor suspended solids in the aerator of last stage by adjusting the sludge recycle and wastage flow rates respectively. The simulation results showed that the sludge age remained nearly constant at a value of 16 d in the variation of the influent characteristics. The mixed liquor suspended solids in the aerator of last stage were also maintained to a desired value of 2500 g/m3 by adjusting wastage flow rates.

Hepatic veno-occlusive disease after hematopoietic stem cell transplantation: Prophylaxis and treatment controversies

Hepatic veno-occlusive disease(VOD), also known as sinusoidal obstruction syndrome, is a major complication of hematopoietic stem cell transplantation and it carries a high mortality. Prophylaxis for hepatic VOD is commonly given to transplant recipients from the start of conditioning through the early weeks of transplant. However, high quality evidence from randomized controlled trials is scarce with small sample sizes and the trials yielded conflicting results. Although various treatment options for hepatic VOD are available, most have not undergone stringent evaluation with randomized controlled trial and therefore it remains uncertain which treatment offers real benefit. It remains controversial whether VOD prophylaxis should be given, which prophylactic therapy should be given, who should receive prophylaxis, and what treatment should be offered once VOD is established.