Chinese Journal of Environmental Engineering 2016 Issue 11 Effect of ozone oxidation process on biological stability of reclaimed water

Effect of ozone oxidation process on biological stability of reclaimed water
LIN Wenqi;,YU Caihong;,LI Guoqiang;,YU Tong;,SHI Xiaojie;,HU Hongying;

..............page:6093-6098

Application research on total nitrogen content forecast of River Miju with improved QGA-BP model
LONG Hua;,ZHAO Jidong;,WANG Xiaodong;,DU Qingzhi;,HU Ting;,SHAO Yubin;

..............page:6099-6105

Effects of temperature on performance of enhanced biological phosphorous removal in activated sludge
PENG Dangcong;,ZHANG Xiaoxia;,FAN Xiangni;,HOU Yanhong;

..............page:6106-6110

Surface modification of chitosan performance contrast research of nanoscale zero-valent iron to remove Cr(Ⅵ)
SUN Yanqiu;,LIU Tingyi;,WANG Zhongliang;

..............page:6111-6117

Treatment of cooling spray water from steelmaking and continuous casting by FA/PFS composite materials
LI Baishan;,ZHOU Peijiang;,WU Liangyu;,SHU Chun;,TANG Shunfu;

..............page:6118-6126

Nitrogen removal performance of anammox coupling heterotrophic denitrification in low concentration of acetate
zhang mei xue ;, li zuo ;, li jun ;, zheng zhao ming ;, xiong xiang yang ;, chen gang ;, yao yuan ;, li qiang ;

..............page:6127-6132

Toxicity reduction on pretreatment of traditional Chinese medicine wastewater by enhanced coagulation
YU Dengxi;,DING Jie;,LIU Xianshu;,ZHANG Luyan;,HUANG Huandi;,JIANG Jinyu;

..............page:6133-6138

Correlations of dissolved Mn and key environmental factors across sediment-water interface of a reservoir
WANG Quanbo;,CHEN Lei;,ZHENG Xilai;

..............page:6139-6146

Nitrate catalytic reduction by zero-valent iron from water over supported catalyst
YANG Xin;,LI Zifu;,YUN Yupan;,WANG Donglin;,ZHAO Junyuan;

..............page:6147-6152

Analysis of characteristics of hydrology and rainwater quality of the dual-substrate-layer green roof
CHENG Long;,WU Qing;,GONG Kena;,WANG Jianghai;

..............page:6153-6158

Effect of DO concentration on removal of ammonium and manganese ion in groundwater by Fe/Mn co-oxides film coating on quartz sands
SHAO Yuezong;,HUANG Tinglin;,SHI Xinxin;,WANG Yang;,CHENG Ya;,BU Hao;

..............page:6159-6164

Simultaneous removal of Rhodamine B and electricity generation in microbial fuel cell with AC/PTFE cathode
TANG Chao;,SUN Zhe;,CHEN DongHui;,HUANG Manhong;,ZHENG Wei;,LIAO Lingzhi;,CAI Qun;

..............page:6165-6170

Preparation of biomass-based carbon membrane and its adsorptive performance for Pb(Ⅱ)
LIU Yuan;,XIA Jingjing;,LIN Jiayu;,ZHANG Yue;,TONG Shitang;

..............page:6171-6178

Treatment of soy protein wastewater by hydrolysis acidification-magnesium ammonium phosphate precipitation-EGSB process
wang lin ;, dai peng fei ;, zhang zuo ming ;, chang yi ;, lv lu ;, xu jing sheng ;, du zuo ;, shi jia jie ;

..............page:6179-6184

Investigation on disinfection efficiency of anultrasound/ ultraviolet all-in-one reactor at a pilot scale
ZHAO Junyuan;,LI Zifu;,ZHOU Zhen;,ZHOU Xiaoqin;,YANG Xin;,WANG Dongling;

..............page:6185-6189

Copper efficiency removal in single-chamber microbial fuel cells
JIN Min;,WU Yining;,ZHAO Xin;,LI Weiming;,LI Shuai;

..............page:6190-6194

NaCl cleaning of organic-fouled ultrafiltration membrane
MI Na;,WANG Lei;,MIAO Rui;,ZHU Miao;

..............page:6195-6199

Impact of water temperature to ozonation water reuse
LI Xiang;,TIAN Yimei;,YANG Qi;

..............page:6200-6204

Effects of groundwater chemistry on chromium(Ⅵ) removal by sulfur-based reducing agents
ZHU Shuai;,ZHANG Xu;,LI Guanghe;

..............page:6205-6211

Removing NH4+-N from surface water by contact oxidation filtration
GUO Min;,HUANG Tinglin;,WEN Gang;,SHI Xinxin;,ZHANG Ruifeng;,SHAO Yuezong;

..............page:6212-6216

Advanced treatment of printing and dyeing tail water from a industrial park by ozonation
HONG Tian;,HU Yongyou;,CHEN Yuancai;,CHENG Jianhua;,LI Wenjie;

..............page:6217-6221

Enhancement of in situ electro-generated hydrogen peroxide via electrochemical process
TIAN Shichao;,LI Yibing;,LIU Huifang;,GUAN Wei;,ZENG Huabin;,ZHAO Xu;

..............page:6222-6228

Evaluation of landscape function of urban lakes based on sensory index
GUO Hongbing;,CHEN Rong;,WANG Xiaochang;

..............page:6229-6234

Application and removal efficiency of phosphorus by new multistage composite constructed wetland
YANG Ting;,LI Cuimei;,ZHANG Yan;,QIAN Lipeng;

..............page:6235-6240

Removal of phosphorus from wastewater by combination of modified biochar and phosphate-accumulating organisms
ZHU Wen;,WANG Xin;,YANG Liuyan;

..............page:6241-6248

Adsorption of vanadium on 13X molecular sieve in aqueous solution
WANG Kunpeng;,LI Ke;,LIAO Wei;,WEI Qingqing;,YANG Jinyan;

..............page:6249-6254

Domestic wastewater treatment by A/O process with an intelligent aeration control system
YANG Oumeng;,HU Zhanbo;,WANG Cui;,WU Huilin;,XU Minyang;,TAKASHI Suemura;

..............page:6255-6260

Characterization of trace mercury adsorption by modified zeolite
ZHU Baohu;,CHEN Xiaomin;,YANG Wen;,JI Hongbing;

..............page:6261-6268

Deep treatment efficiency of electrochemical catalytic oxidation for secondary effluent pharmaceutical wastewater
LIU Junfeng;,HUANG Linlin;,LI Shanshan;,FENG Yujie;

..............page:6269-6274

Phosphorus sorption, release characteristic under different temperature and phosphorus fractions in sediments of Hancheng Lake in Xi'an
YU Jiazhen;,WANG Xiaochang;,XUE Tao;,WANG Wenkai;

..............page:6275-6282

Microorganism characteristics along Biostyr biological aerated filter
WANG Lin;,XIAO Jiaoling;,DOU Nasha;

..............page:6283-6289

Photocatalysis of yttrium doped ZnO nanoparticles
CHEN Zhan;,ZHU Lei;,WANG Xun;

..............page:6290-6294

Adsorption of different polarity BTEX on non-thermal plasma modified activated carbon fiber
JIANG Hao;,SUN Yabing;,ZHANG Mengyi;

..............page:6295-6299

Treatment of simulant marine aquaculture wastewater using sea-water battery
LI Zhonggui;,ZHANG Qiuting;,CHEN Riyao;,CHEN Xiao;,ZHENG Xi;

..............page:6300-6306

Strains screening for producing single cell protein from high concentration fermentation wastewater
ZHOU Yuan;,ZHOU Ziyang;,FENG Li;,CHENG Xiang;,ZHANG Liqiu;

..............page:6307-6312

Comparison of treatment performances of simulated urban sewage in constructed wetlands planted with four types of wetland plant
LIU Wenjie;,XU Xingyuan;,HE Huan;,ZHU Donglin;,XU Ruichen;,SUN Cheng;

..............page:6313-6319

Influencing factors of aniline aerofloat treatment with SBBR method
CHENG Yajie;,SONG Weifeng;,WANG Wei;

..............page:6320-6324

Adsorption of Cd2+ from aqueous solution by modified corn straw biochar and peanut shell biochar
DENG Xiao;,ZHOU Hang;,CHEN Shan;,CHEN Qi;,PENG Peiqin;,LIAO Bohan;,ZHANG Ping;

..............page:6325-6331

Biodegradation of pyrene using naphthalene as cometabolism substrate
WANG Wenjing;,CHEN Hai;,LI Bo;,YANG Qi;

..............page:6332-6336

Preparation of activated carbon with dewatered sludge and its application in semi-coking wastewater treatment
DUAN Jingqi;,LIU Yongjun;,ZHOU Lu;,LIU Yu;

..............page:6337-6342

Pretreatment of triallyl isocyanurate (TAIC) production wastewater by alkaline demulsification-Fenton oxidation process
SUN Yabing;,ZHANG Chunxiao;,XIN Lu;,YU Zhongqing;,ZHANG Guyu;

..............page:6343-6348

Preparation of magnetic BiOI/Fe3O4 and its application in photocatalytic degradation of bisphenol S in aqueous solution
gao sheng wang ;, guo chang sheng ;, lv jia pei ;, hou zuo ;, zhang yuan ;, wang chao jin ;, gao jian feng ;, xu jian ;

..............page:6349-6356

Effect of sludge retention time on performance of anaerobic membrane bioreactor treating kitchen wastewater
HUANG Zhenxing;,XI Kezhong;,XIAO Xiaolan;,MIAO Hengfeng;,ZHAO Mingxing;,SHI Wansheng;,RUAN Wenquan;

..............page:6357-6363

Preparation of PVDF grafted SSS ion exchange membrane by ozone pretreatment
YAN Mingjiao;,WANG Lei;,LI Chen;,WANG Xudong;,TANG Weiting;,SHAN Lan;

..............page:6364-6370

Effects of ammonia on efficiency of iron, manganese and ammonia removal in biological purifying filter
CHENG Qingfeng;,YU Jing;,NENGZI Lichao;,ZHANG Xueqiao;,GUO Junyuan;,XIN Xin;,ZHANG Jie;

..............page:6371-6377

Effect of leachate recirculation ratio on stabilizing process of aerobic bioreactor landfill
KE Jiawen;,QIU Zhongping;,WANG Qiang;,LIU Yang;,YU Gui;,SHU Zhongwen;,LI Xueru;

..............page:6378-6382

Cadmium uptake in paddy rice under combined regulation of soil application of calcium magnesium phosphate and leaf spraying of Si/Se
wang xiao meng ;, ding yong zuo ;, zheng xiang qun ;, zhou li ;, shi rong guang ;, cheng wei min ;, chen zuo ;, yang bo ;, zhang chun xue ;

..............page:6383-6391

Adsorption of metal ions on polypyrrole/chitosan composite electrode
ZHAO Chunxia;,XUE Juanqin;,ZHANG Yujie;,DAI Jizhe;

..............page:6392-6396

Effect of complex humic biological filler on sludge settling property
ZHANG Jukui;,YIN Jun;,SANG Lei;,WANG Ying;,WANG Lining;

..............page:6397-6402

Adsorption of Congo red from aqueous solution by modified cotton shell
WEI Xinlai;,FENG Lingling;,YANG Qian;,YU Zhimin;,WU Ke;

..............page:6403-6408

Synthesis of hydroximic acid functionalized PMMA/AM/HOA resin and its adsorbability for Hg2+ and Cd2+
SUN Lin;,LIU Chunping;,MA Songmei;,SUN Haozhan;,CHEN Qiu;

..............page:6409-6415

Phytoplankton community structure and its relation to environmental factors in landscape lake supplemented with reclaimed water
XU Hongbin;,WANG Wendong;,WANG Nan;,WANG Xiaochang;,ZHANG Yan;,LIU Honglei;

..............page:6416-6424

A recycling method to disused adsorbent after removing copper ions
YANG Jingqi;,LIN Ronghui;,LYU Haixia;

..............page:6425-6430

Effects of hydraulic load on microbial distributions and N2O emissions in a subsurface infiltration system
DUAN Yulong;,LI Yinghua;,LI Haibo;,JI Xianchao;,YU Yanyan;

..............page:6431-6438

Synthesis of magnetic kaolin and adsorption of lead (Ⅱ)
HUANG Ming;,LI Shaofeng;,LU Xiuguo;,RAN Zhilin;

..............page:6439-6445

Humic acid removal and ozonation by-products control in Nano-TiO2/O3 and Nano-TiO2/UV/O3 processes
WU Yue;,WU Chunde;

..............page:6446-6450

Preparation of Fe3O4/ cellulose Nanocomposites and its adsorption to methylene blue
LIN Qingwen;,ZHAO Qi;,GAO Mengfan;,CHANG Jiali;,MA Hongzhu;

..............page:6451-6456

Treatment of acid mine drainage by bentonite composite particles cooperate with SRB
XIAO Liping;,GENG Xinhui;,PEI Ge;,LI Ying;,WEI Fang;

..............page:6457-6463

Novel F-doped Ti/SnO2 electrode for PFOA degradation in aqueous solution
JIANG Chaojin;,ZHUO Qiongfang;,LI Jing;,YANG Bo;

..............page:6464-6468

Study on silver nanoparticles as a solid phase extraction of adsorption of dibenzothiophene
ZHAO Min;,ZHANG Qiang;,LI Na;,MENG Qingxin;,CHEN Liying;

..............page:6469-6472

Oxidation treatment of shale gas drilling wastewater by Fe/C micro-electrolysis combined with H2O2
YANG Demin;,XIA Hong;,CHENG Fangping;,YUAN Jianmei;

..............page:6473-6478

Electrochemical degradation of Acid Red G by titanium-based PbO2 anode
XU Hao;,GUO Wuqi;,ZHANG Lin;,ZHOU Yuantao;,FENG Jiangtao;,YAN Wei;

..............page:6479-6485

Adsorpotion performance of chitosan and sodium alginate composite flocculant
FU Minglian;,ZHENG Junlong;,XUE Lizhen;

..............page:6486-6490

Integration process of decentralized wastewater treatment in hydrolysis acidification-underground infiltration
YU Yanyan;,LI Haibo;,JI Xianchao;,DUAN Yulong;,WANG Shiman;

..............page:6491-6498

Quantitative retrieval of chlorophyll-a concentration in northern part of Lake Taihu based on RBF model
CAO Hongye;,GONG Tao;,YUAN Chengzhong;,JIANG Jinqin;

..............page:6499-6504

Removal of nutrient elements and estrogens in urban tail water by constructed wetland
WANG Liang;,CHEN Pingping;,YUAN Shoujun;,HUANG Deying;,ZHANG Jibiao;

..............page:6505-6512

Adsorption characteristics of Cd2+-containing wastewater onto different bentonites
QIU Huan;,WANG Fenghe;,LI Hui;,CHEN Yajun;,ZHAO Bin;

..............page:6513-6518

Electricity generation of microbial fuel cells using landfill leachate-settled sludge
GAO Xiuhong;,GUO Caifang;,SHI Yingjun;,YANG Chunwei;,SUN Yuwei;,SHI Shuyun;

..............page:6519-6523

Treatment of EDTA-Cu-Ni wastewater by UV/Fenton method
WANG Kaifeng;,PENG Na;,LI Xin;,YAN Zhizhun;,LI Xiuxia;,LU Guining;

..............page:6524-6528

Graphene/Co-Mo carbide as cathodic catalyst in microbial fuel cells
GUO Wenxian;,CHEN Meiqiong;,ZHANG Min;,LIU Peng;,ZHANG Yan;,CAI Zhiquan;,CHENG Faliang;

..............page:6529-6535

Potassium ferrate-Fenton combined process in treating phenanthrene
WANG Yifei;,LI Ya'nan;,WANG Di;,WANG Jianwei;,WANG Guoying;

..............page:6536-6540

Influence of average speed on vehicle exhaust emissions
TIAN Lingdi;,FAN Shoubin;,ZHANG Dongxu;,LIN Yani;,GUO Jinjin;,WANG Junling;

..............page:6541-6548

Adsorption of elemental mercury in flue gas using non-thermal plasma combined with catalyst
liu zuo ;, wang ke ;, su qiu feng ;, zheng cheng hang ;, zhou jin song ;, gao xiang ;, ni ming jiang ;, zuo ke fa ;

..............page:6549-6554

Performance of simultaneous denitrification and desulfurization for Y2O3/AC catalysts
WANG Ting;,DING Lin;,SONG Yongji;,LI Cuiqing;,WANG Hong;,REN Xiaoguang;

..............page:6555-6562

Reaction characteristic of by-product ammonium bisulfate from SCR denitrification and fly ash in air preheater
ma shuang chen ;, deng yue ;, wu wen long ;, zhang li nan ;, chai feng ;, chen fan ;, han ting ting ;, sun pan pan ;

..............page:6563-6570

Experimental research of filtering fine particle by porous media
xing zuo ;, zhao xiao ming ;, liu ying shu ;, li zi yi ;, hong chen ;, yang xiong ;, sun yi fan ;, wang kang ;, liu min ;

..............page:6571-6576

Investigate of CuO loaded on different oxide support for removal of H2S at room temperature
LI Fen;,WEI Jin;,ZHANG Yingmin;,YANG Guanghui;,LI Liang;,WANG Qifei;

..............page:6577-6582

Influencing factors on low-temperature deNOx performance of Mn-La-Ce-Ni-Ox/P84
YANG Bo;,SHEN Yuesong;,QIU Yunshun;,ZENG Yanwei;,SHEN Shubao;,ZHU Shemin;

..............page:6583-6587

Catalytic decomposition of N2O over NiO-MgO composite oxide
DUAN Yankang;,TANG Xiaosu;,SONG Zhongxian;,XIONG Ping;,NING Ping;,ZHANG Qiulin;

..............page:6588-6592

Influence of different angle of inlet and outlet for flow field in cartridge filter
LI Yong;,SONG Huan;,LIU Weidong;,MA Yingya;

..............page:6593-6597

Removing Hg0 from simulation flue gas by using CuCl2 composite materials
YANG Li;,SHI Yingjie;,ZHANG Chen;,SHU Xinqian;,ZHANG Yuxiu;

..............page:6598-6602

Optimization of orifice diameter of injection pipe in bag filter
YIN Gang;,LI Wenbing;,LUO bin;,YUAN Shujuan;

..............page:6603-6607

Removal of SO2 in flue gas by regenerable amine process
FAN Xuan;,LI Xiaofeng;,YAN Huan;,WANG Rui;,CHU Yazhi;

..............page:6608-6612

Influence on leaching of zinc and arsenic in acidified lead-zinc tailings by Acidithiobacillus ferrooxidans
LIN Hai;,ZHOU Yihua;,DONG Yingbo;,XU Weijuan;

..............page:6613-6621

Production of biosyngas from continuous microwave-induced pyrolysis of sewage sludge
LIU Liqun;,ZHANG Jun;,WU Xiaoyan;,TIAN Yu;,ZHANG Jie;

..............page:6622-6628

Parameters optimization of sludge disintegration pretreated by combined alkaline and ultrasonic through response surface methodology
XU Huimin;,HE Guofu;,DAI Lingling;,ZHANG Xiaona;,WANG Zhongyu;,DAI Xiaohu;,XIANG Weining;

..............page:6629-6634

Volatile productions during mixed culture to degrade straw between Trichoderma viride and Phanerochaete chrysosporium
chen yao ning ;, tan xue bin ;, li zuo ping ;, ma zuo ;, zhang jie ;, gou yu ;, liu yao ;, wang yuan nan ;, zhu fu zao ;

..............page:6635-6641

Performance study on solid oxide fuel cell and micro gas turbine combined power generation system fueled with sludge pyrolysis gas
ZHANG Jun;,SUN Qisheng;,WU Xiaoyan;,TIAN Yu;,ZHANG Jie;

..............page:6642-6648

Effect of double enzyme hydrolysis of residual sludge and optimize
LI Yulong;,CAO haijun;,JI Hao;,LI Dengxin;

..............page:6649-6654

Adsorption properties of Cd2+ by bedding materials derived-biochar
WANG Junchao;,ZHENG Kaiqi;,YU Xiaoyan;,XUE Hongbo;,LI Jianhui;,YIN Weiqin;,WANG Xiaozhi;

..............page:6655-6661

A pilot-scale study on the stability of two-phase anaerobic digestion of food waste under thermophilic conditions
li zheng wei ;, yin xiao bo ;, wang xing ;, tang zhi ;, zhang min ;, li qiang ;, wu bo ;, geng yu cong ;, deng ya yue ;

..............page:6662-6668

Experimental about pyrolysis of poly(methyl methacrylate) in a fluidized-bed reactor
XIA Churui;,FAN Xiaoxu;,DING Changfu;,YANG Liguo;,YANG Fan;

..............page:6669-6672

Acid-tolerant cultivation of methanogen and its biogas generation characteristics from food wastes
YANG Lili;,ZHAO Mingxing;,HUANG Yue;,RUAN Wenquan;

..............page:6673-6679

Effect of biosurfactants alkyl polyglycosides on volatile fatty acid production from food waste anaerobic fermentation
TIAN Yuan;,JIANG Jiachao;,SHANG Xiaofu;,LI Meng;,ZHANG Wei;

..............page:6680-6684

Effects of initial pH on bio-hydrogen production from raw municipal sludge
LIU Changqing;,LIN Zhilong;,ZHU Xubin;,CHEN Ximei;,ZHENG Yuyi;,ZHAO Youcai;

..............page:6685-6691

Orthogonal test and gas production potential analysis of reed straw anaerobic fermentation
YAO Li;,FU Longyun;,WANG Yanqin;,YUAN Changbo;,YANG Guang;,LUO Jiafa;

..............page:6692-6698

Effect of bamboo powder content on properties of bamboo paper lime mud/polyvinyl chloride composites
WANG Chuangui;,ZHAO Dong;,YU Kun;

..............page:6699-6704

Engineering characteristics of municipal sludge solidified by municipal solid waste incineration bottom ash as a additive
LIANG Bing;,HU Xuetao;,CHEN Yijun;

..............page:6705-6710

Oil removal by adsorbent produced from oily sludge
TAO Mei;,LIANG Shangwen;

..............page:6711-6719

Optimum of preparation and absorption properties of adsorbent from Frass of Tenebrio Molitor
XIONG Xiaoli;,WANG Chao;,LI Ning;

..............page:6720-6726

Anaerobic fermentation of rice straw and blue algae for biogas under NaOH pretreatment
WU Qiang;,WANG Ning;,LI Yucheng;,DOU Yueqin;,WU Juan;

..............page:6727-6731

Basic research for plant and solid bacterial agent to remediate oil-contaminated soil
wang jing xiu ;, zhang zhi yong ;, sun shan shan ;, mu hong yan ;, wan yun yang ;, zhao li ping ;, li yong feng ;, zhang zhong zhi ;

..............page:6732-6738

Stabilization/solidification of petroleum contaminated soil using biochar-cement
LI Fang;,HAN Qingjie;,MA Fujun;,WU Yuting;,LI Fasheng;,GU Qingbao;

..............page:6739-6745

Research on occurrence characteristics of Chromium in soils and feasibility study of ex-situ soil washing for an abandoned chrome chemicals manufacturing facility
WANG Xuan;,XIONG Huilei;,MA Jun;,XIA Fengying;,PEI Yu;

..............page:6746-6752

Washing kinetics characteristics of Pb and Cd from contaminated soil with FeCl3-citric acid
XU Duanping;,LI Xiaobo;,WANG Yu;,SUN Lu;,CHE Yifu;,LI Hanliang;

..............page:6753-6760

Arsenic accumulation and health risks to human health in major vegetable cultivars of Fuzhou
TU Jiefeng;,LIU Lanying;,WU Yunqing;,CHEN Weiwei;

..............page:6761-6767

In-site experiment on surfactants-enhanced for biodegradation of DDTs-contaminated farmland soils by Arthrobacter globiformis
WANG Xiaoxu;,SUN Lina;,WU Hao;,WANG Hui;,CHEN Su;,LI Huachao;

..............page:6768-6774

Optimized EDTA washing method in remediation of Lead contaminated soil
FEI Xiaotong;,ZHANG Chunlei;,CAO Yali;,YIN Chengqi;,ZHU Chunyou;

..............page:6775-6780

Degradation of anthracene-contaminated soil by ClO2-CuO@montmorillonite catalytic oxidation process
GU Na;,ZHAO Pei;,GAO Jinlong;,MA Yulin;,MENG Xiaoyu;,WANG Kuitao;

..............page:6781-6788

Bioleaching remediation on heavy metal polluted soil using Penicillium Chrysogenum
DENG Xinhui;,PENG Fufeng;

..............page:6789-6794

Performances study on dehumidification and regulating temperature system of monitoring ambient air particulate matter mass concentrations sampling
HUANG Shuanglei;,ZENG Zhiyun;,SUN Kaixuan;,ZHU Zhongbang;,WU Daishe;

..............page:6795-6800