title: A constructed alkaline consortium and its dynamics in treating alkaline black liquor with very high pollution load.
abstract: BACKGROUND
  Paper pulp wastewater resulting from alkaline extraction of wheat straw, known as black liquor, is very difficult to be treated and causes serious environmental problems due to its high pH value and chemical oxygen demand (COD) pollution load. Lignin, semicellulose and cellulose are the main contributors to the high COD values in black liquor. Very few microorganisms can survive in such harsh environments of the alkaline wheat straw black liquor. A naturally developed microbial community was found accidentally in a black liquor storing pool in a paper pulp mill of China. The community was effective in pH decreasing, color and COD removing from the high alkaline and high COD black liquor.
  
  
  RESULTS
  Thirty-eight strains of bacteria were isolated from the black liquor storing pool, and were grouped as eleven operational taxonomy units (OTUs) using random amplified polymorphic DNA-PCR profiles (RAPD). Eleven representative strains of each OTU, which were identified as genera of Halomonas and Bacillus, were used to construct a consortium to treat black liquor with a high pH value of 11.0 and very high COD pollution load of 142,600 mg l(-1). After treatment by the constructed consortium, about 35.4% of color and 39,000 mg l(-1) (27.3%) COD(cr) were removed and the pH decreased to 7.8. 16S rRNA gene polymerase chain reaction denaturant gradient gel electrophoresis (PCR-DGGE) and gas chromatography/mass spectrometry (GC/MS) analysis suggested a two-stage treatment mechanism to elucidate the interspecies collaboration: Halomonas isolates were important in the first stage to produce organic acids that contributed to the pH decline, while Bacillus isolates were involved in the degradation of lignin derivatives in the second stage under lower pH conditions.
  
  
  CONCLUSIONS
  Tolerance to the high alkaline environment and good controllability of the simple consortium suggested that the constructed consortium has good potential for black liquor treatment. Facilitating the treatment process by the constructed consortium would provide a promising opportunity to reduce the pollution, as well as to save forest resources and add value to a waste product.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, People's Republic of China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Yang
authors.forename: Guangchun
authors.initials: G
authors.lastname: Cao
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Zhang
authors.forename: Hongyan
authors.initials: H
authors.lastname: Ren
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Jinhui
authors.initials: J
authors.lastname: Feng
authors.forename: Liping
authors.initials: L
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D001407:Bacillus / Q000378:metabolism; D001547:Benzaldehydes / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry; D002681:China; D004777:Environment; D052918:Environmental Restoration and Remediation / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008031:Lignin / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
chemical_list: D001547:Benzaldehydes; D007220:Industrial Waste; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D002482:Cellulose; D008031:Lignin; C100058:vanillin; D010100:Oxygen