Advanced Materials Research Vols. 726-731

Abstract: The objective of this work is to conduct feasibility studies on water treatment for boiler feeding water use from treated municipal wastewater effluent using a pilot dual continuous ultrafiltration - reverse osmosis (CUF/RO) membrane process with the capacity of 15m³/h. A CUF membrane from HYDRAcap and LFC3-LD RO membrane were used in this study. The CUF unit and RO unit were operated at over 97% and 75-80% water recovery, respectively. The results indicate that CUF process is not only capable of reducing organic and nutrient pollutants but also achieves a silt density index (SDI) less than 2, turbidity of less than 0.47NTU which is suitable for RO treatment. Rejection of the RO unit in terms of average conductivity, COD, hardness, alkaline, NH₄⁺-N, TN, TP were higher than 98.2%, 97.9%, 99.8%, 97.9%, 93.9%, 95.1% and 75%, respectively. Other parameters also can match the quality of high-grade water for use in the boiler industry except pH. Finally, a cost comparison between dual membrane and ion-exchange process showed annual savings of more than 33000000 CNY can be possible.

Abstract: Anaerobic biological technology and bioelectrochemical technology are regarded as promising sustainable wastes treatment processes. With biocatalysis in BESs anode or cathode, various pollutants can be removed. The pollutants range from nitrogen and sulfur to complex compounds. However, the investigation on recalcitrant wastes removal with biocathode has only been reported recently. Recalcitrant wastes, especially chlorinated nitroaromatic compounds, are highly persistent and toxic environmental pollutions which should be removed before discharging to environment. This paper provides a review on anaerobic biocathode BESs for recalcitrant wastes treatment and the feasibility of this system for CANs transformation. It is expected that anaerobic biocathode BESs can provide an appropriate condition for these compounds to transform to easily degradable forms. The technical challenges for future research are also discussed.

Abstract: pH was controlled to 3.0 or 10.0, with pH uncontrolled as blank, to study the release of ammonia and phosphate for different kinds of waste sludge, namely primary sludge (PS), waste activated sludge (WAS), and mixed sludge (MS) composed of PS and WAS at a ratio. The results show that acidity and alkalinity has different effects on different kinds of sludge at room temperature. When the pH is controlled to 10.0, it is observed that ammonia for PS and WAS is rapidly released to the top, 6.53mg/g TS and 8.40mg/g TS on the 4th day. But from the peak value on, the release amount shows downward until the experiment period ends. At pH 3.0 the release amount for PS is little, even less than the blank test, while the release amount for WAS is higher at pH 3.0 in all the period, and arrives at the maximum 10.07mg/g TS on the 6th day, after which the values keep relatively stable. Compared with the release of ammonia, the changes of release amount of phosphate is similar to the two kinds of waste sludge mentioned above, acidity>alkalinity>blank test ,and the amount at pH 10.0 is close to the blank test. Because of high percentage of PS, the release law of ammonia for MS is similar to PS. The order of release amount is as follows: alkalinity>blank test>acidity, but PS is different , the release amount at pH 10.0 always keeps rising until the period ends. The release of phosphate is consistent with the PS and WAS except that it is inhibited under alkaline condition.

Abstract: In this work electrocoagulation for phosphorus removal from wastewater using iron electrodes as cathode and anode was investigated. In this study several parameters were considered namely: distance between electrodes, ammonia and COD with the addition NaCl equal 0.5 g. It was found short gap was better for phosphorus removal and effect of ammonia and COD enhance performance of phosphorus from 89.2 to 90.1 and 91 respectively for a current the 0.8 A at 55 min.

Abstract: Pharmaceuticals and personal care products (PPCPs) have been widely detected in aquatic environment in recent years; as emerging micro-pollutants, their influence on human health and ecological environment safety are of increasing concern. Membrane filtration is considered as the suitable separation method for PPCPs removal due to different removal mechanisms. This paper reviews the removal efficiency and removal mechanisms for PPCPs by NF/RO membranes.

Abstract: The effects of Pb²⁺ concentration, pH and additional carbon source on biodegradation of 4-chlorophenol (4-CP) by Fusarium sp. were investigated, and the characteristic and kinetic of 4-CP biodegradation were analyzed. It was concluded that 4-CP biodegradation rate by Fusarium sp. decreased a little at concentration of Pb²⁺ 0.20 mg/L and 4-CP 50 mg/L. The suitable biodegradation pH was range from 6 to 7. Additional carbon source (phenol) might increase the rate of 4-CP biodegradation. The kinetic equations of 4-CP biodegradation were well accord with the zero order reaction equation at different concentration of Pb²⁺.

Abstract: The quality of water from traditional two-stage biochemical treatment process of papermaking wastewater cannot meet the pollutants discharge standard of paper industry,therefore it is necessary to develop new advanced treatment processes to further treat the effluent. This paper adopts the homogeneous Fenton oxidation technology to treat the effluent from a secondary sedimentation tank of a papermaking factory by batch experiments. The optimum reaction conditions are H₂O₂ dosage 6.54mmol/L, FeSO₄.7H₂O dosage 200mg/L, pH=3, t=1.5h and of all the experiments the dosage of polyacrylamide is 3ppm. The COD of the treated water is under 50mg/L and its removal rate can reach as high as 75.4%, the chroma almost falls to zero, the effluent meets the first grade of the national wastewater discharge standard. Therefore, the homogeneous Fenton is an effective alternative for papermaking wastewater advanced treatment, due to its high effect.

Abstract: Advanced treatment of biochemical treated coking wastewater was studied experimentally with ozonation process. The effects of initial pH value, ozone concentration, reaction temperature, and reaction time on the COD and color removal rate were investigated. The results showed that ozonation was an effective method for advanced treatment of biochemical treated coking wastewater. The increasing of initial pH value, ozone concentration, reaction temperature, and reaction time has enhanced the removal rate of COD and color. Meanwhile, the results also revealed that the maximal COD and color removal rate of 69.65% and 92.27% could be reached under the optimal conditions of the initial pH value is 10.5, ozone concentration is 150 mg/L, reaction temperature is 298 K, and reaction time is 30 min.

Abstract: Coking wastewater is a kind of recalcitrant wastewater including complicate compositions. Advanced treatment of coking wastewater by Fenton-Like reaction using pyrite as catalyst was investigated in this paper. The results show that the chemical oxygen demand (COD) of coking wastewater decreased significantly by method of coagulation combined with two-stage oxidation reaction. COD of wastewater can decrease from 250mg/l to 45mg/l after treatment, when 2g/L pyrite was used in each stage oxidation and the dosage of hydrogen peroxide (H₂O₂) is 0.2ml/l for first stage treatment, 0.1ml/l for second stage treatment respectively. The pyrite is effective to promote Fenton-Like reaction with low cost due to high utilization efficiency of H₂O₂, moreover, catalyst could be easily recovered and reused. The Fenton-Like reaction might be used as a potential alternative to advanced treatment of recalcitrant wastewater.

Abstract: In this paper, the poplar Alkaline Peroxide Mechanical Pulp (APMP) pulping wastewater was treated by the SBR. The pulping wastewater was from the processes of washing, soaking and defibrination. The COD of the pulping wastewater was 5671 mg/L and the BOD was 1862 mg/L. The B/C (biological oxygen demand/chemical oxygen demand) ratio of the pulping wastewater was 0.32, which indicated that the wastewater was suitable to be treated by biological methods. SBR technology was used to treat the pulping wastewater. After a series of experiments, the best conditions for the pulping wastewater was achieved as follows: time 6hrs, original pH about 8. Under these conditions the removal ratio of COD can reach 81.4% and that of BOD can reach 91.5%;but the removal ratio of the TSS and the Chromaticity were low, the removal ratio of TSS only reach 31.8%.