造纸废水是我国污染最为严重的难降解工业废水之一,研究了电离辐射处理造纸废水的可行性,探讨了混凝、辐照以及混凝-辐照组合工艺对废纸造纸废水的COD、BOD5、吸光度、DOC以及有机物相对分子质量分布的影响.实验发现,造纸废水的COD主要是由相对分子质量〈3 000的有机物构成,相对分子质量为1 000~3 000的有机物对COD的贡献占44.5%,相对分子质量〈1 000的有机物对COD的贡献占41.6%.混凝能够有效去除造纸废水中相对分子质量〉3 000的有机物,去除率达到44.7%,相对分子质量〈3 000的有机物去除率仅为20.0%,并且显著降低废水的吸光度,提高了辐照对于相对分子质量1 000~3 000以及相对分子质量1 000以下有机物的降解效率.混凝可以沉降部分的大分子有机物,使得辐照后紫外吸收波降低;而辐照降低了小波长(〈250 nm)范围内的吸收峰,而在大波长(〉250 nm)处吸收峰增高.辐照对造纸废水中的有机物可能同时具有降解和聚合作用,对相对分子质量〉3 000的有机物聚合作用大于降解作用,对相对分子质量〈3 000的有机物的降解作用占据主要优势.混凝-辐照组合工艺不但有效去除造纸废水中相对分子质量〉3 000的有机物,而且能够提高相对分子质量1 000~3 000和相对分子质量1 000以下有机物的可生化性.混凝-辐照组合工艺对于造纸废水的处理具有很好的互补性.
Paper mill effluent is one of the most refractory industrial wastewater in China.The feasibility of treating paper mill effluent by ionizing radiation was studied experimentally.This article investigated the effect of coagulation,ionizing radiation,and the combined process of coagulation and ionizing radiation on COD,BOD5,absorbance DOC and molecular weight distribution of soluble organic compounds in paper mill effluent.It was found that COD of wastewater consist of organic compounds(Mr3 000).The organic compounds(1 000Mr3 000) made 44.5% contribution to COD and Mr1 000 41.6%.Coagulation technology can effectively remove the organic compounds(Mr3 000) with its removal rate of 44.7%.But the organic compounds(Mr3 000) was only removed by 20.0%.Coagulation can also reduce the absorbance of wastewater significantly and improve the efficiency of ionizing irradiation for the degradation efficiency of organic compounds(Mr3 000).The macromolecule organic compounds were coagulated so as to make UV wavelength decreased after irradiation.The absorption peak(250 nm) was decreased by irradiation,meanwhile the absorption peak(250 nm) increased.However,there are both degradation and polymerization effects for organic compounds in paper mill effluent by radiation technology.The polymerization shows greater effect compared with the degradation for organic compounds(Mr3 000),while the effect is opposite for organic compounds(Mr3 000).Combined process of coagulation and ionizing radiation not only effectively remove organic compounds(Mr3 000) in paper mill effluent,but also increases the biodegradability of organic compounds(Mr3 000).Therefore,the combined process of coagulation and ionizing radiation possesses highly effective applicability for paper mill effluent.