Gu Guowei

Long-term monitoring and prediction for leachate concentrations in Shanghai refuse landfill.

Parameters such as pH, concentrations of Cl-, turbidity,NH3-N, CODCr and BOD5 (simplified as COD and BODrespectively in the following text) in leachate generated inthe large-scale testing landfill unit and closed landfill unitsat Shanghai Refuse Landfill were monitored from April 1995 toOctober 1998. The mathematical simulation formula between theseparameters and refuse age were established based on the dataobtained from the testing landfill unit and justified by thedata obtained at the closed landfill units from 1989 to 1993.The long-term predictions for the leachate concentrations forthe Landfill were made using the mathematical simulation formulaestablished. It was predicted that the COD and BOD may bereached to the strictest standard for pollution control on municipal solid wastes landfill in China, i.e., COD < 100 mg L-1 and BOD < 30 mg L-1, after 15 yr natural attenuation. The time predicted for NH3-N concentrations to reach the discharging standard, 15 mg L-1, was found to be at least 23–26 yr or even longer. The predictions for concentrations of Cl-, turbidity, and pH values in leachate are also given. The natural attenuation of Cl- is the slowest and might be decreased to 200 mg Cl- L-1, the agricultural irritation standard, after at least 58 yr.

A comparison of refuse attenuation in laboratory and field scale lysimeters

For this study, small and middle scale laboratory lysimeters, and a large scale field lysimeter in situ in Shanghai Refuse Landfill, with refuse weights of 187,600 and 10,800,000 kg, respectively, were created. These lysimeters are compared in terms of leachate quality (pH, concentrations of COD, BOD and NH3-N), refuse composition (biodegradable matter and volatile solid) and surface settlement for a monitoring period of 0-300 days. The objectives of this study were to explore both the similarities and disparities between laboratory and field scale lysimeters, and to compare degradation behaviors of refuse at the intensive reaction phase in the different scale lysimeters. Quantitative relationships of leachate quality and refuse composition with placement time show that degradation behaviors of refuse seem to depend heavily on the scales of the lysimeters and the parameters of concern, especially in the starting period of 0-6 months. However, some similarities exist between laboratory and field lysimeters after 4-6 months of placement because COD and BOD concentrations in leachate in the field lysimeter decrease regularly in a parallel pattern with those in the laboratory lysimeters. NH3-N, volatile solid (VS) and biodegradable matter (BDM) also gradually decrease in parallel in this intensive reaction phase for all scale lysimeters as refuse ages. Though the concrete data are different among the different scale lysimeters, it may be considered that laboratory lysimeters with sufficient scale are basically applicable for a rough simulation of a real landfill, especially for illustrating the degradation pattern and mechanism. Settlement of refuse surface is roughly proportional to the initial refuse height.

Leachate production and disposal of kitchen food solid waste by dry fermentation for biogas generation

This laboratory research, which applies anaerobic digestion for a solid phase batch system using kitchen food solid waste (KFSW), is concerned with optimizing leachate production under different conditions. The solid-phase digestion process is expected to be superior to slurry-phase digestion and the so-called “dry fermentation” process. A batch system solid waste reactor was used in the present study. The performance of the reactor was tested under the conditions of constant temperature of 35°C and the reactor active volume was 12 l. On operation day 10, chemical oxygen demand (COD) for leachate extraction parameters such as COD rate, COD loading rate (LR) and COD concentration reached maximum values, and were 135 g COD/d, 11 g COD/1.d, and 214 g/l of COD, respectively. On day 25, accumulative leachate COD reached the top value of 1509.4 g.

Phosphorous Removal in Intermittent Cycle Extended Aeration System Wastewater Treatment Plant - Effect of Temperature

Wafangdian wastewater treatment plant (WTP) employed intermittent cycle extended aeration system (ICEAS), which was the first application in the northeast of China. WTP achieved good performance in the past almost three-year operation with effluent quality of COD 26~52 mg/L (40 mg/L in average), BOD 6~17 mg/L (11 mg/L in average), NH4 +-N 0.68~7.79 mg/L (3.87 mg/L in average), TN 11.61~19.44 mg/L (15.58 mg/L in average), SS 2~19 mg/L (11 mg/L in average) and TP 0.50~1.02 mg/L (0.88 mg/L in average). The average removal efficiency was COD 82%, BOD 87%, NH4 +-N 78%, TN 46%, SS 93% and TP 76%, respectively. The phosphorous removal efficiency in Wafangdian WTP was higher in winter, while lower in summer. The possible reasons for phosphorous removal were discussed, and the temperature was an important factor for the competition between phosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) in full-scale Wafangdian WTP.

Preliminary study on treatment of waste organic matter from livestock by bacteria-mineral technology

The present study dealt with relationships between the degradation and humification process that the organic matter underwent during bacteria-mineral technology. An inverse correlation was found between the protein, lipid, and some of the humification indices considered, suggesting that the humification theory is actually humic substances produced from simple-structured natural organic substrates. Weight-average molecular weight (Mw), number-average molecular weight (Mn), and the ratio Mw/Mn of dissolved organic matters at different stages of the process were measured by gel permeation chromatography. The results showed that Mn and Mw increased with reaction time from 352 to 17,191, and from 78,707 to 104,564, respectively. The ratio of Mn/Mw decreased from 223.3 to 6.1. This reflected the growth of the polymerization degree of dissolvable organic matters in the process; furthermore, it indicated the formation of complex molecules (humic substances) from more simple molecules. Bacteria-mineral water (BMW) (the effluent of the process) treatments can exert hormone-like activity for enhanced seed germination of wheat and rice and greatly improved chlorophyll synthesis in wheat and rice leaves. Major polyamines (plant regulators) putrescine, spermidine, and spermine, were found in BMW by a high performance liquid chromatography (HPLC) method, which may explain the hormone-like activity of BMW.