Integrated Treatment Process Research Articles

Rate and extent NOM removal during oxidation and biofiltration

The presence of natural organic matter (NOM) in drinking water treatment presents many challenges. Integrated treatment processes combining oxidation and biofiltration have been demonstrated to be very effective at reducing NOM, specifically biodegradable organics. Laboratory bench-scale experiments were carried out to investigate the effect of oxidation by ozonation or UV/H2O2 on NOM. Specifically the rate of biodegradation was studied by performing bench-scale biodegradation experiments using acclimatized biological activated carbon (BAC). For the source water investigated, oxidation did not preferentially react with the biodegradable or non-biodegradable NOM. In addition, the type or dose of oxidation applied did not affect the observed rate of biodegradation. The rate kinetics for biodegradation were constant for all oxidation conditions investigated. Oxidation prior to biofiltration increased the overall removal of organic matter, but did not affect the rate of biodegradation of NOM.

Highly integrated hybrid process with ceramic ultrafiltration-membrane for advanced treatment of drinking water: A pilot study

This article presents a highly integrated hybrid process for the advanced treatment of drinking water in dealing with the micro-polluted raw water. A flat sheet ceramic membrane with the pore size of 50∼60 nm for ultrafiltration (UF) is used to integrate coagulation and ozonation together. At the same time, biological activated carbon filtration (BAC) is used to remove the ammonia and organic pollutants in raw water. A pilot study in the scale of 120 m3/d has been conducted in Southern China. The mainly-analyzed parameters include turbidity, particle counts, ammonia, total organic carbon (TOC), UV254, biological dissolved organic carbon (BDOC), dissolved oxygen (DO) as well as trans-membrane pressure (TMP). The experiments demonstrated that ceramic UF-membrane was able to remove most of turbidity and suspended particulate matters. The final effluent turbidity reached to 0.14 NTU on average. BAC was effective in removing ammonia and organic matters. Dissolved oxygen (DO) is necessary for the biodegradation of ammonia at high concentration. The removal efficiencies reached to 90% for ammonia with the initial concentration of 3.6 mg/L and 76% for TOC with the initial concentration of 3.8 mg/L. Ozonation can alter the molecular structure of organics in terms of UV254, reduce membrane fouling, and extend the operation circle. It is believed the hybrid treatment process developed in this article can achieve high performance with less land occupation and lower cost compared with the conventional processes. It is especially suitable for the developing countries in order to obtain high-quality drinking water in a cost-effective way.

Design of Integrated Treatment Process of Municipal Solid Waste in Shanghai

Based on analysis of municipal solid waste (MSW) in Shanghai city, a related integrated treatment process of MSW was studied. MSW was classified into organic, combustible, recyclable and other parts. The designed integrated treatment process includes mixed waste sorting, anaerobic digestion of the biodegradability organic waste, RDF production systems of combustible waste and deodorizing system. Organic MSW is digested under anaerobic conditions and produce biogas for power generation for electricity plant. The residue can be used to prepare organic and inorganic fertilizer; Combustible MSW has low water, high calorific value and can be prepared RDF; The recyclable trash (plastic, metal) are on sale. Other MSW is land filled. The designed integrated treatment process may provide a route to solve the problems of MSW in Shanghai.

INTEGRATED TREATMENT OF LEACHATE FROM MUNICIPAL WASTE SOLID LANDFILL

The present paper proposes an integrated-treatment process of leachate from a municipal landfill, which involves two treatment steps. The first step consists in diminishing the organic content through an advanced oxidation process using ozone and hydrogen peroxide. The second step is performed in order to diminish the content of heavy metals through a sorption process on a natural low-cost biosorbent, thus the traces of organic substances remained after oxidative degradation or oxidation-intermediate products are removed. From the point of view of the oxidative process of organic substances in the leachate can be mentioned the simultaneous action of two strong oxidants such as ozone. A mineralization rate related to COD-Cr of around 20 % is obtained after approximately four hours of pretreatment using an ozone generator with a productivity of 0.5 g Ozone corresponding to an energy consumption less then 1kWh. At the same time, a maximum 65 % decolorization is achieved. Using moss peat from Poiana Stampei (Romania) as biosorbent, removal rates of 95% is achieved in case of leachate solution containing 2.19 mg/L of copper ions. In relation to the organic content, the sorption treatment rates ranges between 12 and 18%, which correspond to a total organic content of 770 mg O2/L.

Integrated treatment process using a natural Wyoming clinoptilolite for remediating produced waters from coalbed natural gas operations

Coalbed natural gas (CBNG) development in western U.S. states has resulted in an increase in an essential energy resource, but has also resulted in environmental impacts and additional regulatory needs. A concern associated with CBNG development relates to the production of the copious quantities of potentially saline-sodic groundwater required to recover the natural gas, hereafter referred to as CBNG water. Management of CBNG water is a major environmental challenge because of its quantity and quality. In this study, a locally available Na-rich natural zeolite (clinoptilolite) from Wyoming (WY) was examined for its potential to treat CBNG water to remove Na + and lower the sodium adsorption ratio (SAR, mmol 1/2 L − 1/2 ). The zeolite material was Ca-modified before being used in column experiments. Column breakthrough studies indicated that a metric tonne (1000 kg) of Ca-WY-zeolite could be used to treat 60,000 L of CBNG water in order to lower SAR of the CBNG water from 30 to an acceptable level of 10 mmol 1/2 L − 1/2 . An integrated treatment process using Na-WY-zeolite for alternately treating hard water and CBNG water was also examined for its potential to treat problematic waters in the region. Based on the results of this study, use of WY-zeolite appears to be a cost-effective water treatment technology for maximizing the beneficial use of poor-quality CBNG water. Ongoing studies are evaluating water treatment techniques involving infiltration ponds lined with zeolite.

Evaluation for the Reclamation Potential of High-Tech Industrial Wastewater Effluent Treated with Different Membrane Processes

Due to the shortage of water supplies, the reclamation and reuse of the effluents from wastewater treatment plants has become an important issue in Taiwan, especially for industrial parks. By constructing a reclaimed water distribution system, the reclaimed water could be used as nonpotable and industrial water. This research used three advanced integrated treatment processes, including sand filtration (SF), microfiltration (MF), granular activated carbon (GAC), ion exchange (IE), reverse osmosis (RO), and an ultraviolet disinfection (UV) unit, to treat the effluent from the wastewater treatment plant of Hsin-Chu Science-Based Industrial Park. The reclamation potential of treated water was examined compared with different water reuse criteria. The results of the experiments showed that different process could achieve different levels of water purification. This was dependent on the complexity and sequence of the units. The effluent from the simplest process, called process A, which combined the SF, MF, GAC, and UV units in that order, could meet the criteria of nonindustrial water. The effluent of process B and C, which additionally installed IE–MF–RO and MF–RO–IE units in sequence, respectively, between the GAC and UV units of process A, could be reused as sprinkling, landscaping and recreational water; cooling-system makeup water; low-pressure boiler feed water; as well as potable water or Newater with suitable advanced treatment.

Treatment of praziquantel wastewater using the integrated process of coagulation and gas membrane absorption

Praziquantel is an anti-schistosoma drug, its wastewater contains numerous cyanide and other colloid pollutant. A novel integrated treatment process was proposed in this study, i.e., using coagulation to eliminate colloid pollutant and using gas membrane absorption (GMA) to remove cyanide. The optimization of coagulation condition, determination of cyanide removal rate, elimination of membrane fouling, and overall evaluation of the integrated process for the treatment of praziquantel wastewater were investigated in this study. Good results were achieved: turbidity reduced from 700 NTU to 10–40 NTU, 92% COD was removed, cyanide concentration dropped from 3500 mg/L to below 0.5 mg/L, recovery rate of cyanide reached to 98%, and operation cost could be entirely compensated from the gain of recovered cyanide. The results demonstrate that the novel integrated process offers a number of advantages over alkaline chlorination method in the treatment of praziquantel wastewater: cyanide can be reused rather than destroyed, no secondary pollutants are produced, the operation cost is low and the equipment etching is avoided.

Leaching behaviour of a galvanic sludge in sulphuric acid and ammoniacal media

Leaching studies of a sludge produced by the physico-chemical treatment of wastewaters generated by a Ni/Cr plating plant were carried out in both sulphuric acid and ammoniacal media aiming to decide which of them would be the best treatment for this kind of waste material. The dissolution behaviour of some metals (Cu, Ni, Cr and Zn) was studied in order to assure the best metal recovery conditions in subsequent processes by the use of some separation methods such as solvent extraction and precipitation techniques. Therefore, the study here presented deals with the first chemical stage of an integrated treatment process. For the sulphuric acid leaching, maximal conversions obtained were 88.6% Cu, 98.0% Ni and 99.2% Zn for the following experimental conditions: a 100 g L −1 acid concentration, a 5:1 liquid-to-solid ratio (L/S), a particle size less than 1 mm, a digestion time of 1 h, a stirring speed of 700 rpm (all at room temperature and under atmospheric pressure). As expected, no selectivity was achieved for the sulphuric acid leaching, despite this option yielding much higher metal ion dissolution when compared with that reached by ammoniacal leaching. The use of this latter medium allowed the extraction of Cu and Ni without Cr species, but rates of conversion were only about 70% for Cu and 50% for Ni, much lower than those obtained for sulphuric acid leaching.

Ozone and Biofiltration Optimization For Multiple Objectives

Biofiltration can be an effective drinking water treatment process when ozonation is practiced beforehand. The objectives and therefore the designs of these two processes are usually not related to biological treatment goals, and no effort has been made to determine the compatibility of the goals of these integrated treatment processes. The optimal application of ozone (O3) for disinfection is the minimum dose that provides a target level of microorganism inactivation. This dose was equivalent to the optimal O3 dose for biological treatment, defined as the minimum dose that would achieve the maximum relative BDOCrapid removal. Additionally, the O3 process is limited with respect to controlling the formation of BDOCrapid. Increasing the O3 dose beyond the optimal dose will result in little additional BDOCrapid formation, little additional release of biodegradable dissolved organic carbon to the distribution system, and an increase in the cost of operation. A conceptual approach for optimizing the O3 and biofiltration processes for biological treatment objectives is described for three case studies. The results indicate that biological treatment goals can be satisfied to a large degree while simultaneously meeting other drinking water treatment objectives such as disinfection and particle removal.

Benefits of ozone-activated carbon filtration in integrated treatment processes, including membrane systems

Amsterdam Water Supply introduced ozone-activated carbon filtration (biological activated carbon filtration) in the production plant Leiduin in 1995. This full-scale plant (capacity 70 million m 3 yr −1 ) can be characterized as an integrated treatment process. Experience since 1995 has revealed that biological activated carbon filtration has several benefits in integrated treatment processes. It is a very effective barrier for organics in general and for pesticides and organic micropollutants in particular. Due to the preceding ozonation both adsorption and biodegradation take place, resulting in a very long lifetime of the carbon filters (2 years). The ozonation significantly increases the disinfection capacity of the plant. Together with the other process steps, the disinfection capacity is at such a high level that, in combination with the biological stability of the finished water and good engineering practice in the distribution system, no chlorination has to be applied to guarantee hygienic quality. The process stability of the final treatment step, slow sand filtration, is, importantly, increased by the introduction of ozone-activated carbon filtration. Running times of the slow sand filters are longer than 2–3 years, while before the introduction of ozone-activated carbon filtration they never exceeded 1 year. In integrated membrane processes—which may be used in the treatment plant Leiduin in the future and therefore are being tested on pilot plant scale—ozone-activated carbon filtration also offers many advantages. In a reverse osmosis pretreatment scheme, comprising ozone-activated carbon filtration and slow sand filtration, the reverse osmosis system was shown to have a running time of 1 year without any membrane cleaning, due to the excellent reverse osmosis feed water quality. The application of ozone-activated carbon filtration also enables the use of electrodialysis as an alternative for reverse osmosis in an integrated membrane system. It is concluded that ozone-activated carbon filtration is a versatile process, offering many benefits in integrated treatment systems.

Assessment of partial treatment of polyethylene glycol wastewaters by wet air oxidation

The pretreatment of a model, polyethylene glycol-containing wastewater by wet air oxidation was studied in the context of integrated chemical and biological treatment processes. Both semibatch and continuous uncatalysed experiments were carried out at temperatures from 383 to 473 K, residence times up to 60 min and an oxygen partial pressure of 2.8 MPa. The concentration of total organic carbon (TOC) and chemical oxygen demand (COD) was followed throughout the reaction. Combined parameters and simple analytical techniques were used and provided a straightforward assessment of the chemical pretreatment efficiency with respect to partial oxidation and polymer degradation. It was found that at the conditions under consideration, partial oxidation dominates over total oxidation and is accompanied by substantial fragmentation of the original polymer to lower molecular weight compounds. Semibatch operation favours higher TOC and COD removal rates than continuous operation, while continuous operation generally favours higher partial oxidation efficiencies than semibatch operation. The benefits arising from the assessment of the extent of chemical pretreatment for the rational design of integrated treatment processes are also discussed.

Biological nutrient removal with an internal organic carbon source in piggery wastewater treatment

The feasibility of using an internally available carbon source for biological nitrogen and phosphorus removal was investigated. A new integrated animal wastewater treatment process consisting of two reactors was operated with various sequences for the treatment of high strength piggery manure. The treatment process was operated with real-time control technology, which utilized the oxidation–reduction potential (ORP). In the first operation, the sludge in each reactor was completely separated (sludge separation strategy, SSS), while a portion of the sludge in the first reactor was added into the second reactor in every cycle of the second operational strategy (sludge addition strategy, SAS). None of the operating strategies used a supplemental carbon source to achieve enhanced phosphorus release and denitrification. By achieving successful real-time control, very high removal efficiencies of organic matter, nitrogen and phosphorus were obtained in both operations. These high performances were mainly achieved by means of biological mechanisms, not chemical and physical processes. The real-time control made it possible to utilize an internally available organic material for phosphorus removal and denitrification of produced NO x -N, without any external carbon source. Furthermore, it was found that an optimization of aeration periods could be achieved by using the tested real-time control technology, since the technology stopped the aeration when the targeted oxidation status occurred in treatment system. The HRT obtained in both the SSS and the SAS was proportional to the F/M ratio. Experimental data showed that the sludge addition strategy (SAS) has a practical advantage over the sludge separation strategy (SSS), in that the SAS enhanced the denitrification and resulted in constant and low effluent NO x -N concentrations.

Integrated Wet Air Oxidation and Biological Treatment of Polyethylene Glycol-Containing Wastewaters

The treatment of a model wastewater containing polyethylene glycol (PEG) of molecular weight 10000 in an integrated wet air oxidation–aerobic oxidation process was investigated. Partial wet air oxidation under mild operating conditions was capable of converting the original polymer to lower molecular weight compounds, such as oligomers and short-chain organic acids. The effect of molecular weight on the aerobic biodegradability of polyethylene glycol was assessed by performing shake flasks experiments with various polyethylene glycols in a molecular weight range from 200–35000 and it was found that biodegradability generally decreased with increasing molecular weight. Aqueous solutions of PEG 10000 were subjected to continuous wet air oxidation at a temperature of 423 K and a residence time of 30 min and the oxidised effluents were then subjected to subsequent continuous aerobic oxidation at residence times varying between 0·5 and 4 days. Simultaneously, continuous aerobic oxidation experiments on solutions of PEG 10000 were performed and used to compare the efficiency of the integrated treatment process with that of the direct biological treatment. Partial pretreatment by wet air oxidation under mild operating conditions resulted in effluents whose biodegradation rates were significantly higher than those of the original, unoxidised wastewater, as assessed by total organic carbon (TOC) removal rates. The original wastewater was practically non-biodegradable at a 0·5-day residence time with direct biological treatment, while an 80% TOC removal was achieved when biological treatment was coupled with a preceding wet air oxidation step. Conversely, with a 4-day residence time for the direct biological treatment the original wastewater was only partially degradable with 60–70% TOC removal recorded; with the integrated treatment process at a 4-day residence time in the bioreactor the overall TOC removal was greater than 90%. © 1997 SCI

Integrated Wet Air Oxidation and Biological Treatment of Polyethylene Glycol‐Containing Wastewaters

The treatment of a model wastewater containing polyethylene glycol (PEG) of molecular weight 10000 in an integrated wet air oxidation–aerobic oxidation process was investigated. Partial wet air oxidation under mild operating conditions was capable of converting the original polymer to lower molecular weight compounds, such as oligomers and short-chain organic acids. The effect of molecular weight on the aerobic biodegradability of polyethylene glycol was assessed by performing shake flasks experiments with various polyethylene glycols in a molecular weight range from 200–35000 and it was found that biodegradability generally decreased with increasing molecular weight. Aqueous solutions of PEG 10000 were subjected to continuous wet air oxidation at a temperature of 423 K and a residence time of 30 min and the oxidised effluents were then subjected to subsequent continuous aerobic oxidation at residence times varying between 0·5 and 4 days. Simultaneously, continuous aerobic oxidation experiments on solutions of PEG 10000 were performed and used to compare the efficiency of the integrated treatment process with that of the direct biological treatment. Partial pretreatment by wet air oxidation under mild operating conditions resulted in effluents whose biodegradation rates were significantly higher than those of the original, unoxidised wastewater, as assessed by total organic carbon (TOC) removal rates. The original wastewater was practically non-biodegradable at a 0·5-day residence time with direct biological treatment, while an 80% TOC removal was achieved when biological treatment was coupled with a preceding wet air oxidation step. Conversely, with a 4-day residence time for the direct biological treatment the original wastewater was only partially degradable with 60–70% TOC removal recorded; with the integrated treatment process at a 4-day residence time in the bioreactor the overall TOC removal was greater than 90%. © 1997 SCI

Man's control of water quality.

Abstract